essay on air pollution in delhi

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Delhi Air Pollution [UPSC Notes]

India’s national capital New Delhi is known for being one of the world’s most polluted cities, with the problem getting particularly severe in the winter months. What is the reason for Delhi’s air pollution? What are the mitigation measures being taken by the government? In this article, you can read all about Delhi’s air pollution problem and the ways this can be resolved. This is an important topic for the UPSC exam environment and ecology segments.

The article is important for the Environment section of the UPSC Syllabus.

The aspirants can read more relevant information from the links provided below:

Air Pollution in Delhi

India is one of the most polluted countries in the world and among the capital cities, Delhi is probably one of the most polluted cities. Indian cities feature largely in the top 50 polluted cities of the world according to many parameters. 

The problem, however, is particularly severe in the capital Delhi and its adjoining areas, commonly called Delhi – NCR. 

• The Environment Performance Index 2020 gives India a global ranking of 169.
• Air pollution (both indoors and outdoors) is the second-most serious risk factor for public health in the country (the first being malnutrition) and it contributes to an estimated 2.5 million deaths annually.

But what makes Delhi’s air pollution so severe compared to the rest of the country, and what specifically makes it more harmful during the winter months? This is discussed in the following sections.

Causes of Air Pollution in Delhi

Air pollution is the introduction into the atmosphere of chemicals, particulates, or biological materials that cause discomfort, disease, or death to humans, damage other living organisms, damage the natural and the built environment.

The severe air pollution that affects life is not restricted to Delhi but to a huge airshed around it that includes the NCR. This encompasses Gurgaon, Faridabad, Ghaziabad, Noida, places in Haryana, UP, and even Alwar (Rajasthan).

The most important causes of air pollution in Delhi and adjoining areas are as follows:

• Increasing population and related developmental activities at the cost of environmental damage.
• The development of the region has largely been unplanned and often, industrial units that spew harmful chemicals into the atmosphere are located in residential and commercial areas and not designated areas.
• Increased vehicular traffic (which has not come down despite the Delhi metro) and the consequent rise in air and noise pollution.
• Almost 8,000 m tonnes of solid waste is being generated in Delhi (National Environmental Engineering Research Institute) every day, however, the authorities manage to clear only about 5000 – 5500 m tonnes of waste daily. This adds to the garbage piling up. This is not counting the hazardous and non-hazardous waste from industries.
• There is a rather high dependence on fossil fuels, whose burning causes a lot of emission of harmful gases into the atmosphere.
• Large scale construction activities lead to increased dust pollution, which leads to around 56% of PM10 and the PM2.5 load.
• The landlocked geography of Delhi also causes more air pollution as compared to other cities. The north-westerly winds coming from Rajasthan, sometimes Pakistan and Afghanistan bring in the dust to the region. The Himalayas obstruct the escape route of the air. This causes the dust and pollutants to settle in the region. This is more prominent during the winters because of low-level inversion (upward movement of air from the layers below is stopped). It is because of this landlocked geography of Delhi that it faces greater pollution when compared to the coastal city of Chennai (where despite high automobile population, has the sea breeze which provides an effective entry and exit for dispersing pollutants).
• Stubble burning also contributes to the air pollution in the region. During the winter months, the large scale stubble burning practised in Punjab, Haryana and Rajasthan cause a thick blanket of smog to cover Delhi-NCR. According to a study, the burning of crop residue released about 149 million tonnes of carbon dioxide, more than 9 million tonnes of carbon monoxide, 0.25 million tonnes of oxides of sulphur (SOX), 1.28 million tonnes of particulate matter (PM) and 0.07 million tonnes of black carbon. As evident, it contributes to a lot of greenhouse gas emissions.
• Firecrackers, although not the top reason for air pollution, also contributes to the problem.

Problems Caused by Air Pollution

• Air pollution severely affects human health. It is found to cause low birth weight in children, tuberculosis, asthma, ischemic heart disease, nasopharyngeal and laryngeal cancers, cataracts, etc.
• According to some research, air pollution can also impair cognitive development.
• Air pollution is associated with infections & diseases that kill around 600,000 children under five years of age every year.
• Several studies reveal a higher prevalence of symptoms of chronic bronchitis in areas with higher particulate air pollution.
• Nearly 2.5 million people die worldwide each year from the effects of outdoor or indoor air pollution. (National Geographic)
• Air pollution also affects the environment adversely. Many pollutants are greenhouse gases and this leads to global warming. Burning fossil fuels releases carbon dioxide which has the biggest impact on global warming.

Steps Taken to Control Delhi’s Air Pollution

Various steps have been taken by the government (central and state governments) to tackle the menace of air pollution in Delhi-NCR. Some of the measures are given below.

• In October 2020, the Supreme Court-appointed a one-man committee, Justice Lokur Committee , to monitor and curb the occurrences of stubble burning in Punjab, Haryana and Uttar Pradesh. Read more about this committee in CNA dated Oct 17, 2020 .
• These are institutionalised measures to be taken only when the air quality in Delhi NCR deteriorates beyond a certain threshold.
• It is only to be implemented in emergency situations.
• The steps would be taken to prevent PM10 and PM2.5 levels to go beyond the ‘moderate’ national Air Quality Index (AQI) category.
• GRAP enumerates a series of measures to be taken based on the quality of air.
• In the case of severe+ category, one of the measures also includes shutting down of schools.
• Read more on the Graded Response Action Plan in the linked article.
• Construction & demolition (C&D) waste management rules have been notified which mandate the segregation of C&D waste into various categories for safe disposal and further processing.
• Red Light On, Gaadi Off campaign was an initiative by the Delhi Government that ran in Oct-Nov 2020 under which commuters driving vehicles were urged to switch off their vehicle engines while waiting for the green light at traffic lights.
• The Odd-even rule was introduced by the Delhi Government according to which vehicles with odd and even registration numbers would ply on the road on alternate days. This was particularly aimed at reducing smog in the region.
• The state government of Delhi also introduced a policy to preserve and plant trees in a bid to increase the green cover and have carbon sinks.
• Anti-smog guns and smog towers are installed and used in the city.
• The subsidy is provided to the farmers for procuring the Turbo Happy Seeder, which is a machine fitted on tractors that can cut and uproot stubble and eliminates the need to burn stubble.
• The ICAR has also come up with the PUSA Decomposer, which is a capsule that can be used to make a spray which when sprayed on crop residue hastens its decomposition.
• Mass Rapid Transport System (MRTS) is being built as a means to provide citizens with non-polluting alternative sources of transportation.
• The adoption of the Bharat Stage VI norms and the big push being given to electric vehicles steps in the right direction in curbing vehicular pollution.

Way Forward

Reducing air pollution in the national capital is a pressing need for which both the governments and the citizens should play their part. The government should enforce all the legislations necessary and see to it, and they are properly implemented. Citizens should comply with the laws and regulations and do their part as well. Afforestation measures should be encouraged. Renewable energy sources should be adopted more and the usage of electric vehicles encouraged, for which the necessary infrastructure should also be built. Farmers should also be provided with viable alternatives to stubble burning.

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Delhi, the world’s most air polluted capital fights back

Subscribe to global connection, vinod thomas and vinod thomas distinguished fellow - asian institute of management, manila, former senior vice president - world bank @vthomas14 chitranjali tiwari ct chitranjali tiwari associate fellow - jk lakshmipat university, jaipur.

November 25, 2020

After an unexpected respite as coronavirus lockdowns stalled economic activity, air  pollution  has returned to  pre-COVID-19 levels in Delhi, the world’s most air polluted capital city  (Figure 1).

Last month, ahead of the usual spike in winter, the Delhi administration launched an antipollution campaign. But to win, nothing short of sustained action on  multiple fronts  will suffice. Other Asian capitals too have faced pollution crises. But Delhi’s is extreme because of a combination of smoke from thermal plants and brick kilns in the capital region, effluents from a congested transportation network, stubble or biomass burning by farmers in neighboring states, and the lack of cleansing winds that causes air pollution to hang over the city. Even as technical solutions are within reach, the campaign must overcome the poor policy coordination among central, city, and local governments.

Delhi’s toxic haze is a deadly health risk to its residents, particularly children, the elderly, and the ill. Particulate matter—PM2.5 and PM10—far exceeds national and World Health Organization limits and is the  main culprit  for Delhi’s high incidence of cardiovascular damage. The city’s toxic air also contains high quantities of sulfur dioxide, nitrogen oxide, and carbon monoxide, putting people at  higher risk  of strokes, heart attacks, and high blood pressure, and worsening the respiratory complications from  COVID-19.

The main sources of Delhi’s particulate emissions are, in equal measure, particles from large power plants and refineries, vehicles, and stubble burning. The experiences of Bangkok, Beijing, and Singapore suggest that an ambitious but feasible goal is to cut air pollution by one-third by 2025, which, if sustained, could extend people’s  lives  by two to three years. The current effort is designed to confront all three sources, but strong implementation is needed.

Delhi is moving simultaneously on three fronts: energy, transport, and agriculture. In each case, East Asia offers valuable lessons.

• Coal-fired plants. Delhi’s environment minister has called for the closure of  11 coal-fired power plants operating within 300 kilometers of Delhi. But policy implementation must improve: All the plants have missed two deadlines to install flue-gas desulfurization units to reduce sulfur dioxide emissions. Last year,  10 coal-fired  power plants missed a December deadline to install pollution control devices.  Beijing provides valuable lessons in cutting concentrations of PM2.5 more than  40 percent  since 2013. Beijing substituted its four major coal-fired stations with natural gas plants. The city government ordered  1,200 factories  to shut with stricter controls and inspections of emitters.  Bangkok  had success with its inspection and maintenance program.
• Cleaner transport . Delhi has tried  pollution checking of vehicles by mobile enforcement teams, public awareness  campaigns , investment in mass rapid transport systems, and phasing out old commercial vehicles. The Delhi government’s recent  push  for electric vehicles shows promise, while the response of industry and the buy-in from customers will be key. Overall results in cutting pollution have been weak because of poor governance at every level. Better outcomes will be predicated on investment in public transportation, including integration of transport modes and last-mile connectivity. Unfortunately, Delhi Transport Corporation’s fleet  shrank  from 6,204 buses in 2013 to 3,796 buses in 2019, with most of the bus fleet aging. Delhi should look at  Singapore’s  regulation on car ownership and use; its improved transit systems; and promotion of pedestrian traffic and nonmotorized transport.
• Better farming practices . Burning of crop stubble in Delhi’s neighboring states has become a serious source of  pollution in the past decade. In 2019, India’s Supreme Court ordered a complete halt to the practice of stubble burning and reprimanded authorities in two of these states, Punjab and Haryana, for allowing this illegal practice to continue. Needed is the  political will to act , as poor farmers complain that they receive no financial support to dispose of post-harvest stubble properly. Delhi’s  “Green War Room”  signaling the fight against the smog, is analyzing satellite data on farm fires from Punjab and Haryana to identify and deal with the culprits. The  Indian Agricultural Research Institute  has proposed a low-cost way to deal with the problem of stubble burning by spraying a chemical solution to decompose the crop residue and turn it into manure. Better coordination is needed. In 2013, when  Singapore  faced a record-breaking haze due to agricultural waste burning in neighboring countries, the Environment Agency and ministries of education and manpower together issued guidelines based on a Pollution Standards Index to minimize the health impacts of haze.  Stubble burning  has been banned or discouraged in China, the United Kingdom, and Australia.

Delhi, projected to be the world’s most  populous  city by 2030, is motivated by a sense of urgency. Facing a growing environmental and health calamity, antipollution efforts are being strengthened. But to succeed, the different levels of government must harness the political will to invest more, coordinate across boundaries, and motivate businesses and residents to do their bit.

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• 10 November 2023

Why is Delhi’s air pollution so bad right now?

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Air pollution is spiking in Delhi, a megacity of more than 30 million people. Credit: Arun Thakur/AFP via Getty

As the Hindu festival of Diwali kicks off on 10 November, the Indian capital of Delhi, already blanketed in choking smog, is bracing for pollution to worsen. Over the past week, children struggling to breath the acrid air have flooded hospital emergency departments , and schools have been forced to close . Why is Delhi’s air pollution so bad right now?

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Air pollution in Delhi, India: It’s status and association with respiratory diseases

Abhishek dutta.

Department of Environmental Science, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok, Thailand

Wanida Jinsart

Associated data.

Data Availability: Air quality data of Delhi that support the findings of this study are owned by the Central Pollution Control Board (CPCB). For further information about the air quality data please visit https://cpcb.nic.in/real-time-air-qulity-data/ or https://app.cpcbccr.com/ccr/#/dashboard-emergency-stats . Meteorological data of Delhi can be obtained from the Regional Meteorological Centre, India Meteorological Department ( https://rmcnewdelhi.imd.gov.in/ ). Both for data and permission to use the data, please contact the Deputy Director General of Meteorology (DDGM), Regional Meteorological Centre, Lodi Road, New Delhi – 110003 via E-mail: moc.liamg@ihledwencfwr . Daily hospital visit data between the years 2016 and 2018 for respiratory diseases (ICD-10) J00-J99, used in this study, were collected from Vardhman Mahavir Medical College Safdarjung hospital, Ansari Nagar East, New Delhi. For data and permission to use data please contact the Medical Superintendent M.S. Office, New OPD Building, Safdarjung Hospital, New Delhi-110 029.Tel (011-26190763), e mail: ni.cin.hjs-cmmv@eciffosm .

The policymakers need research studies indicating the role of different pollutants with morbidity for polluted cities to install a strategic air quality management system. This study critically assessed the air pollution of Delhi for 2016–18 to found out the role of air pollutants in respiratory morbidity under the ICD-10, J00-J99. The critical assessment of Delhi air pollution was done using various approaches. The mean PM 2.5 and PM 10 concentrations during the measurement period exceeded both national and international standards by a wide margin. Time series charts indicated the interdependence of PM 2.5 and PM 10 and connection with hospital visits due to respiratory diseases. Violin plots showed that daily respiratory disease hospital visits increased during the winter and autumn seasons. The winter season was the worst from the city’s air pollution point of view, as revealed by frequency analyses. The single and multi-pollutant GAM models indicated that short-term exposure to PM 10 and SO 2 led to increased hospital visits due to respiratory diseases. Per 10 units increase in concentrations of PM 10 brought the highest increase in hospital visits of 0.21% (RR: 1.00, 95% CI: 1.001, 1.002) at lag0-6 days. This study found the robust effect of SO 2 persisted in Delhi from lag0 to lag4 days and lag01 to lag06 days for single and cumulative lag day effects, respectively. While every 10 μg m -3 increase of SO 2 concentrations on the same day (lag0) led to 32.59% (RR: 1.33, 95% CI: 1.09, 1.61) rise of hospital visits, the cumulative concentration of lag0-1 led to 37.21% (RR: 1.37, 95% CI:1.11, 1.70) rise in hospital visits which further increased to even 83.33% (RR: 1.83, 95% CI:1.35, 2.49) rise at a lag0-6 cumulative concentration in Delhi. The role of SO 2 in inducing respiratory diseases is worrying as India is now the largest anthropogenic SO 2 emitter in the world.

1. Introduction

Time and again, the policymakers felt the requirements of understanding the status of air pollution in growing cities and association of short-term air pollution exposures spanning one or a few days on morbidity. This is particularly more relevant for the world’s fast-growing cities to accrue benefits of sustainable development. Epidemiological studies conducted in the past in cities held air pollution responsible for inducing different health hazards. The quasi-poison regression model within over-dispersed Generalized Additive Model (GAM) has been very handy for many researchers for exploring the association of air pollution with different morbidity and mortality [ 1 – 6 ]. In a time series where the respondent variable depends on the nonlinear relationship of independent variables, GAM model finds its best applicability. In GAM, the nonlinear confounders can be controlled using smooth functions to correctly estimate the best connection between dependent and independent variables [ 7 – 12 ]. Accordingly, researchers used the GAM model extensively to indicate the role of air pollution in causing health effects for US and European cities [ 13 , 14 ].

Chinese and Indian cities frequently grabbed the world’s attention because of increasing air pollution and reported health effects on city dwellers. Indian cities were in the limelight because of the uncontrollable nature of air pollution in already declared polluted cities. Different Chinese cities have been put under strict scanners by the researchers who continuously reported or updated the policymakers on air pollution and health hazards so that policy-level initiatives may defuse the situation. Recently Lu et al. [ 15 ] reported that research ably supported the polluted Chinese cities to progress in air pollution control and place the much-needed strategic air quality management system. Another recent article indicated that out of 31 research papers published during 2010–2020 investigating the role of different air pollutants on the health of city dwellers using the GAM model, the majority, i.e., 17 were in the backdrop of Chinese cities and 3 for Indian cities [ 16 ]. GAM successfully explored the role of different pollutants in establishing their relationships with different types of respiratory morbidity/mortality for 21 cities of China, India, Iran, Brazil. Denmark and Kuwait ( S1 Table ). Zhao et al. [ 17 ], using GAM, reported that Dongguan city dwellers in China faced the threat of enhanced respiratory diseases due to short term exposure to CO. Song et al. [ 18 ] found respiratory diseases amongst the children of Shijiazhuang city of China due to PM 10 , SO 2 , NO 2 presence in the air. Cai et al. [ 19 ], studied the total respiratory diseases mortality of Shenzhen, China, and linked them with PM 2.5 presence in ambient air through GAM modelling. Liang et al. [ 20 ] used GAM model to indicate a direct relationship between pulmonary disease in Beijing with air pollution. Very recently Wang et al. [ 21 ] confirmed the role of particulate matter (PM) with pneumonia hospitalizations of children in Hefei, China.

Delhi, the capital city of India, is the second most populated and one of the most polluted cities in the world and should be the obvious choice for pollution and health hazard research. The recent air quality report of IQ Air has ranked Delhi first out of the air-polluted capital cities of 106 countries based on PM 2.5 concentration [ 22 ]. According to WHO, Delhi is the sixth-worst polluted city amongst 13 notable other Indian cities. Indeed, the city-dwellers had terrible times when PM 2.5 of Delhi stood at 440 μg m -3 during October 2019, i.e., 12 times the US recommended level. Past studied blamed the huge transport sector with the largest vehicle stock of the country as the critical emission source [ 23 – 27 ]. Chen et al. [ 28 ] demonstrated that local transport emissions and neighboring states contributed dominantly to PM 2.5 and O 3 concentration strengthening in Delhi. Sreekanth et al. [ 29 ] found high PM 2.5 pollution persists across all the seasons in Delhi despite pollution control efforts in vogue. In the pan-Indian context, air pollution significantly contributed to morbidity and premature mortality in India for a long time [ 30 ]. Sharma et al. [ 31 ] reviewed 234 journal papers and noted the knowledge gaps in connecting hospital admissions of patients with air pollution of Delhi. Balyan et al. [ 32 ] also noted that a deeper understanding of ambient pollutants at the city level and their effect on morbidity was lacking.

Against the background above, the primary objective of this paper to explore the environmental data of Delhi for confirming the poor air quality status of the city and, after that, assess the role of air pollutants with morbidity (respiratory diseases) through the application of the GAM model. A more profound grasp of the city air quality and influences of ambient air pollution on respiratory diseases is much needed. Such studies may provide all critical information for initiating actions to curb air pollution, health risk, developing public health policies, and above all, a strategic environmental management system for Delhi.

2. Study location

As a highly populated and polluted city, Delhi provides an opportunity to apply the GAM model for ascertaining how much the prevailing air pollution is responsible for respiratory diseases of the city dwellers. Delhi has spread over 1,483 km 2 and a population size of about 11 million per the 2011 census study. With time Delhi emerged as a significant city of the country so far as commerce, industry, medical service, and education are concerned. As per Köppen’s climate classification, Delhi’s climate is extreme with five seasons. The summer is scorching (April–June), while winter is freezing (December-January). The average temperature range during the summer is between 25°C to 45°C, while the winter temperature range is between 22°C to 5°C [ 33 ]. The comfortable season spring prevails from February to March, and autumn runs from mid-September to late November. The rainy monsoon season spans almost three months, starting from July. Air pollution varies across seasons due to the influence of climatic conditions [ 34 ].

3. Materials and methods

3.1. air pollution data.

Daily average data for three years, January 2016 to December 2018, (1096 data points) of key air pollutants were collected from the State Pollution Control Board (SPCB), Delhi. The pollutants were sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ), carbon monoxide (CO), particulate meter 10 micrometers or less (PM 10 ), and particulate meter 2.5 micrometers or less (PM 2.5 ) as recorded by 11 NAMP (National Air Quality Monitoring Programme) stations of the city as shown in Fig 1 and S2 Table .

3.2. Meteorological data

Time series meteorological data for 1 January 2016–31 December 2018 were collected from Regional Meteorological Department located in Delhi. The data were of a total of 1096 days and included daily average temperature (T), daily average relative humidity (RH), daily average wind speed (WS), and daily rainfall (RF). The collected meteorological and air monitoring data will be adequate to estimate the confounding effect of meteorological conditions on morbidity related to respiratory diseases using GAM model.

3.3. Hospital visit data

We considered respiratory diseases covered by J00-J99 under the ICD-10 classification system. Data related to daily hospital outpatient visits of patients for respiratory diseases under International Classification of Diseases-10 (ICD-10), J00-J99 for 2016–2018 (1096 days) were collected from Safdarjung Medical College and Hospital (SMCH) of Delhi. The SMCH had its existence from pre-independence days of India and now functioning under the Ministry of Health and Family Welfare, Government of India. SMCH has many different specialties and super specialty departments, and Respiratory Medicine (RM) is one. Fig 1 shows that all the 11 air pollution monitoring stations considered in this study are located within a road distance of 12 km from SMCH. The hospital records contained information related visit date of patients, age, gender, and final medical diagnosis for each patient. The patient data were grouped age-wise under three categories (i) elderly people (more than or equal to 65 years), (ii) middle-aged (45–64 years), and (iii) young (less than or equal to 44 years). For hospital data collection formal request letter was submitted to the hospital authority. As the data were old data without identifiers and not having any possibility of ascertaining the identities of the individuals to whom the data belong, the hospital waived IRB approval.

3.4. Methods of analysis

3.4.1 summary statistics and analysis of time series.

Summary statistics of climatic variables, air pollutants, and hospital visits of the patients such as mean, standard deviation, maximum, minimum, and different quartiles were computed using the SPSS 25 version of the software. Daily hospital visit counts for three years (2016–2018) in SMCH were structured based on the patient’s age, sex, and visit dates. Violin plots were developed for three air pollutants (PM 10 , PM 2.5 , and CO), two climatic variables (T, RH), and hospital visits of patients regarding five seasons of Delhi, indicating the distribution of data prevailing in the city during different seasons. Violin plots have been drawn with XLSTAT statistical software. Time series plots were developed using the SPSS 25 version of the software with time dimensions on the horizontal axis and hospital visits, pollutants and, meteorological variables on the vertical coordinate axes to shed light on the data distribution for three years.

3.4.2 Frequency analysis

The seasonal distribution of PM 2.5 and PM 10 concentrations in Delhi during 2016–18 has been done by frequency analysis [ 35 ]. Under frequency analysis, first, the city level average concentrations of PM per day were calculated by averaging the concentration of 11 monitoring stations. Then, PM concentrations (both for PM 10 and PM 2.5 ), i.e., number of per day observations for the period 2016–18 falling under six categories like 0–25, 25–50, 50–100, 100–200, 200–300, and more than 300 μg m -3 worked out. So, the three-year period (2016–18) data or 1096 observations were segregated session-wise for each of the six categories, and the frequency of their appearances was then expressed in percentage terms. The calculations were done with the help of data analysis ’ToolPak’ of excel. As per the air quality index (AQI) Of India, the range 0–100 is considered a good category, 100–200 as moderate, 200–300 as poor, and above 300 as very poor or severe.

3.4.3 Correlation analysis

To understand the interrelationship between climatic variables and air pollutants data for Delhi (2016–2018), we executed Pearson correlation analysis using SPSS version 25.0 (SPSS Inc., Chicago, IL, USA) software. The coefficients of correlations were established between daily meteorological variables and air pollutants for Delhi. The correlation coefficients at p < .01 were accepted as statistically significant [ 36 ]. For better visualization, correlation matrix plots have been drawn with R software’s ’corrplot’ package.

3.4.4 Generalized Additive Models (GAM)

The nonlinear associations of various independent variables (climatic variables and criteria pollutants) and the outcome variable (hospital visits due to respiratory diseases) of Delhi can be better explained by (GAM) model. GAM explicitly allows the relationship between outcome variables independent variables to be developed based on the smooth functions fitted to some independent variables, thereby bringing the flavor of parametric relationships of the covariates in a regression model [ 37 , 38 ]. Accordingly, in this study, the potential confounding effects of few independent variables that entered the regression model were controlled with non-parametric smoothening splines. Smoothening splines of 7 degrees of freedom (df) per year were fitted to calendar time (time since 1 January 1970) to control long-term trends and possible calendar effects [ 39 , 40 ]. In line with Wei [ 41 ] smoothening splines with 7 df were also applied to mean RH and mean temperature (T) to control their respective confounding effects on the regression model. A linear term of mean wind speed (WS) was allowed to prevail. A dummy variable as the day of the week (DOW) was additionally introduced in the categorical form to control for week effects. As per Peng et al. and Zheng et al. [ 39 , 42 ], the dfs for smoothing splines were allowed to be determined by the generalized cross-validation (GCV) scores. Finally, based on the description of the regression model formation above, we formed the following GAM model ( Eq 1 ) in our present study with usual notations and applied.

where i denotes the day of observation; E ( Y i ) denotes the daily hospital visits expected due to respiratory diseases; β denotes regression coefficient; X i denotes the daily mean concentration of pollutants; s stands for the smoothing spline applied, and α is the intercept. Once the basic GAM model is set with the smoothing splines for RH, T, and time variables, the independent variables like PM 2.5 , PM 10 , NO 2 , SO 2 , and CO (per day concentrations) were added to the basic model to make it the multi-pollutant GAM model. We also constructed two single pollutant models for PM 2.5 and PM 10 , respectively, to understand their respective sole effects on respiratory diseases related to hospital visits in the city under study. In the single-pollutant model, PM 2.5 and PM 10 concentrations, in turn, were entered as independent variables in the base model. Generally, single pollutant models do not reflect the synergistic effect of pollutants on morbidity, but in consideration with the multi-pollutant models, they provide crucial complementary understanding.

The respective coefficients of pollutants of the multi-pollutant and single-pollutant GAM models, found out as regression model output, were the inputs in deriving the relative risk (RR) of hospital visits due to one unit rise of each modelled air pollutants in the ambient air.

Past studies have shown that the air pollutants remain in the ambient air and create lingering effects on morbidity. Accordingly, we have considered pollutant concentrations for a single day and multiple days in the study. We tested the lingering effects of air pollution for single-day lags and cumulative lag days. Single-day lag (lag0) means air pollutant concentrations on the same day of the hospital visit, while lag6 indicates air pollutant concentrations of 6 days before the hospital visit. Similarly, for cumulative concentrations of pollutants lag0-1indicate the mean of pollutant concentration of the current day and previous day of the hospital visit (i.e., 2 days mean). Similarly, lag 0–2 indicates the mean of current day pollutant concentration, 1 day before and 2 days before the visit (i.e. 3 days mean). In the same way, lag0-3, lag0-4, lag0-5, and lag0-6 means 4 days, 5 days, 6 days, and 7 days mean pollutant concentrations, respectively. We used single lags of 0, 1, 2, 3, 5, and 5 days (lag0–lag 5) and cumulative lags of 0–1, 0–2, 0–3, 0–4, 0–5, and 0–6 days (lag 0–1 to lag0-6) to explore the lag pattern of health effects in the multi pollutants and single pollutant models. The R software with "mgcv" package (version 4.0.2) was applied to construct the GAM models. For visualizations of GAM models developed in this study, we have used visual tools of the mgcViz R package.

3.5. Relative Risk (RR)

Relative risk (RR), often used in epidemiological studies, helps understand the risk of the outcome of an intervened event with non-intervened events. Thus, RR compares one group with another group. In this study, the exposure-response coefficient β of pollutants obtained from the GAM models under different lag conditions have been used to estimate RR and their 95% confidence intervals (95% CIs). RR for the i th predictor variable and its confidence intervals were calculated using the following Eqs 2 , 3 and 4 .

where Δ C i is the rise of the i th pollutant concentration in air and S.E i is the standard error of i th pollutants. Here, Δ C will be 1 unit increase in CO and 10 units increase in all other pollutants. RR provides information on the rise of hospital visits due to each unit increase of a pollutant’s concentration level. To make the RR estimates of daily hospital visits due to air pollution more expressive, we also calculated the percentage change (PC, %,) at 95% CI in the following way ( Eq 5 ).

PC = Percentage change of daily hospital visits due to air pollution

In all analyses p-value < 0.05 considered significant.

4. Results and discussion

4.1 data distribution and time-series analyses.

The distribution of criteria pollutants, climatic variables (T and RH), and daily counts of hospital visits in Delhi are placed in Table 1 for 2016–18. Table 1 indicates that the mean value of PM 2.5 and PM 10 concentrations exceeded the guidelines of NAAQS and WHO both by a wide margin. They shoot to as high as 693.08 μg m - ³ for PM 10 and 478.25 μg m - ³ for PM 2.5 during 2016–2018. The mean RH value of 58.5% (range, 98.3% to 12.5%) in Delhi indicates the city’s humid condition higher than the ideal level relative humidity for health and comfort of 30–50%. The three years mean temperature of 25.63 ± 7.65 °C with a maximum as high as 45°C and a minimum of 0.5°C along with a higher level of RH indicates the extreme climate of Delhi. Daily mean hospital visits of patients for respiratory diseases during 2016–18 was 20±23.52.

Table 2 reveals that a total of 22,253 patients visited SMCH, Delhi, either for outpatient consultation or admission for respiratory diseases during 2016–2018, as retrieved from hospital records. The maximum number of people who visited the hospital for respiratory ailments for a day was 176, and the minimum 0 patients. Out of the total patients, 63.5% were female, and 30% had ≥65 years of age. Similarly, out of male patients, 52% were aged ≥65 years, as shown in Table 2 .

Time series charts in ( Fig 2A–2F ) depict behaviors of meteorological variables (RH, temperature), air pollutants (PM 2.5 , PM 10 , and CO), hospital visits, and their interrelationship during 2016–2018 for Delhi. PM 2.5 and PM 10 were positively correlated in Delhi during 2016–18, indicating the interdependency ( Fig 2A ) while maintaining a positive correlation with hospital visits due to respiratory diseases ( Fig 2B and 2C ). Fig 2D–2E shows that hospital visits tended to negatively correlate with RH and temperature. Fig 2(F) shows a positive correlation of hospital visits with CO concentration too in the city’s environment.

The time series of Delhi from 2016–2018 (A) PM 2.5 Vs Hospital visit, (B) PM 10 Vs Hospital visit, (C) RH Vs Hospital visit, (D) T Vs Hospital visit, (E) CO Vs Hospital visit, (F) PM 2.5 Vs PM 10 .

Violin plots of three air pollutants (PM 10 , PM 2.5 , and CO), two meteorological variables (T, RH), and hospital visits of patients were drawn for the five distinct seasons of Delhi have been provided in ( Fig 3A–3F ) below. Fig 3A indicates that PM 2.5 dominates the city environment during winter and autumn. Fig 3B indicates that PM 10 dominates the city air during the winter and summer seasons, but the median value of PM 10 concentrations was higher during winter. The concentration of CO in the air remains high during winter and low during the monsoon season ( Fig 3C ). Fig 3D clearly shows that the city experiences comparatively higher RH during summer and monsoon, with the highest median value during monsoon. Fig 3E indicates that the city experiences the hottest season during summer and autumn. From Fig 3F , it can be observed that during the winter and autumn season’s daily hospital visits due to respiratory diseases increased. The rectangles within the violin plots indicate finishing points of the first and third quartile of data distribution with central dots as medians. The upper and lower whiskers show data spread.

(A) PM 2.5 , (B) PM 10 , (C) CO, (D) RH, (E) Temperature, (F) Hospital visit.

4.2 Seasonal distribution of PM 2.5 and PM 10 in Delhi

The frequency distribution of PM 2.5 and PM 10 concentrations for five Delhi seasons are shown in Fig 4 . Fig 4 indicates that the winter season was terrible from the air pollution point of view as almost 95.2% of the time, the ambient PM 2.5 concentrations recorded to be more than 100 μg m -3 . Alarmingly, 100% of the time, the ambient PM 10 concentrations crossed the 100 μg m -3 benchmark during winter, indicating very harsh wintertime for the city dwellers. The spring season brought some relief for the city dwellers when 42.2% of the time PM 2.5 concentrations crossed 100 μg m -3 benchmark, but PM 10 remained very strong with 99.4% of the time crossing the 100 μg m -3 benchmark. During summer, about 76.9% of the time PM 2.5 concentrations were under the ’good’ category, and 15.8% of the time PM 2.5 concentrations were more than the 100 μg m -3 benchmark. During summer PM 2.5 concentrations improved considerably with only 15.8% of the time, its concentrations were more than the 100 μg m -3 benchmark, but PM 10 remained razing with 97.8% time crossing 100 μg m -3 benchmark. However, two and half months of monsoon (July, August, and mid-September) brought relief from PM 2.5 pollution. Almost 100% of the time, PM 2.5 concentrations remained under the ’good’ category, but PM 10 remained 51.1% crossing the 100 μg m -3 benchmark during monsoon. From autumn (mid-September to late November), PM pollution built up with 97.8% of the time PM 2.5 concentrations crossing 100 μg m -3 benchmark, as shown in Fig 4 . In summary, the frequency distribution of PM 2.5 and PM 10 concentrations indicates that except winter, the PM concentrations remained very high, which could be a possible cause of health hazards for the city dwellers.

4.3 Correlation between pollutants and meteorological variables

Positive correlation existed between two important gaseous pollutants SO 2 and NO 2 (r = 0.341), while PM 10 maintained a mild positive correlation with SO 2 (r = 0.281). PM 10 almost had linear positive correlation both with NO 2 (r = 0.783) and CO (r = 0.733) as shown in Table 3 and Fig 5 . PM 2.5 also had positive correlation with SO 2 (r = 0.137), and positive linear correlation with NO 2 (r = 0.673) and CO (r = 0.757). Also, PM 10 and PM 2.5 maintained positive linear correlation.

Blue, red, and while indicate positive, negative, and no correlation respectively.

**. Correlation is significant at the 0.01 level (2-tailed).

*. Correlation is significant at the 0.05 level (2-tailed).

4.4 Association of criteria pollutants with respiratory diseases, Delhi

Multi-pollutant and single pollutant GAM models were formed for Delhi to understand the impact of air pollutants on hospital visits due to respiratory diseases. Multi pollutant models indicate combined effects of the involved pollutants on the hospital visits, whereas single pollutant GAM models cast light on the sole effect of pollutants. The models were tested with different lag concentrations to comprehensively understand the impact of short-term exposure of pollutants on hospital visit counts due to respiratory diseases.

4.4.1. Association of criteria pollutants with respiratory diseases in Delhi (multi-pollutant models)

In the multi-pollutant model, criteria pollutants for 2016–18 were included in the base GAM model. Table 4 and Fig 6 indicate the relative risks (RR) of hospital visits due to a rise of 1 unit increase in CO and 10 units for all other pollutant concentrations for different single lag days. The RR patterns in Table 4 indicate synergistic effects of criteria pollutants on respiratory diseases related hospital visits in the city. Table 4 reveals that both PM 2.5 and PM 10 concentrations of all the 6 single lag days had no significant effect on respiratory disease-related hospital visits. The effect of NO 2 on hospital visits was there during lag1 day concentrations only but without any positive acceleration. The effect of SO 2 on respiratory diseases-related hospital visits was found to be robust instantaneously, i.e., the increase of every 10 ppb SO 2 on the same day (lag 0) resulted in a 32.6% (RR: 1.326, 95% CI: 1.089, 1.614) rise in hospital visits. The effect of SO 2 on hospital visits persisted throughout the lag days from lag0 up lag4. The increase in CO on hospital visits throughout the different lag days (lag0 to lag6) was found to be non-significant for respiratory diseases.

* Figs. in the brackets indicates PC (% change in hospital visits)

Note: p < 0.05, p < 0.01, and p < 0.001 considered significant

Table 5 and Fig 6 below indicate the relative risks (RR) pattern of change in hospital visits due to a rise of 1 unit increase in CO and 10 units for all other pollutant concentrations for different cumulative concentrations of pollutants. Both for PM 2.5 and PM 10 , in terms of cumulative days effect of air pollution, no significant effect could be found. NO 2 and CO were also not significantly responsible for enhancing respiratory diseases in the city. However, per 10 ppb rise in cumulative lag days, concentrations of SO 2 led to a comparatively more robust effect on respiratory diseases than single-day lag effects. At lag0-1 per 10 ppb, rise in concentrations of SO 2 was associated with the percentage change in hospital visits of 37.21% (RR: 1.372, 95% CI: 1.107, 1.701), which increased to 83.34% (RR: 1.833, 95% CI: 1.351, 2.489) during the lag0-6 day. The result indicates the robust effect of pollutants SO 2 on respiratory disease-related hospital visits in Delhi.

Note: p < 0.05, p < 0.01, and p < 0.001 considered significant.

Figs ​ Figs7 7 and ​ and8 8 below, drawn with the "mgcViz" R software package (Fasiolo et al., [ 43 ], provide the visual representation of the smoothing applied to the non-parametric terms and performance of the GAM model at lag0 respectively.

4.4.2. Association of criteria pollutants with respiratory diseases in Delhi (Single-pollutant models)

Two single-pollutant models were developed with pollutants PM 2.5 and PM 10, respectively, to understand the sole effect of PM pollution on respiratory diseases. We fitted different single lag days and cumulative lag days to express the association of daily hospital visits for respiratory diseases with a 10μg m -3 increase in PM 10 or PM 2.5 in Delhi. Both PM 2.5 and PM 10 did not show any significant association with the number of respiratory disease-related hospital visits in Delhi for all the single lag days considered here, as revealed by the p values ( Table 6 and Fig 9 ). In other words, the association of PM 2.5 and PM 10 with the respiratory disease was negligible as RR was found to be less than the baseline (RR<1).

*Note: p < 0.05, p < 0.01, and p < 0.001 considered significant

However, in cumulative exposure single-pollutant models, PM 10 was found to have persistently enhanced hospital visits of patients with the respiratory disease excepting lag 0–2 days, as shown in Table 6 . Table 6 shows that per 10 units increase in concentrations of PM 10 brought the highest increase in hospital visits of 0.21% (RR: 1.002, 95% CI: 1.001, 1.002) at lag0-6 days. PM 2.5 association with respiratory disease-related hospital visits found to be non-significant during all the cumulative lag days considered.

5. Conclusion and discussion

The study investigated first the level of air pollution in Delhi and then assessed the impact of air pollution on respiratory diseases. The result suggests that Delhi has been struggling to cope up with the increasing nature of criteria pollutants in the first place. A total of 22,253 patients visited the Delhi hospital either for outpatient consultation or admission for respiratory diseases for 2016–2018. The study found that the mean value of PM 2.5 and PM 10 concentrations for the period 2016–2018 were 107.32±71.06 μg m -3 and 210.61±95.90 μg m -3 for Delhi, respectively, which were substantially higher than the NAAQS and WHO standards. Out of the five seasons in Delhi, the winter season is hugely dominated by PM 2.5 and PM 10 pollution, as revealed by frequency analyses. Initial time series analysis revealed that PM 2.5 maintained a positive correlation with PM 10 have while PM 2.5 , PM 10 , and CO maintained a positive correlation with hospital visits during 2016–18 in Delhi. Pearson correlation analysis confirmed that PM 10 in Delhi had almost positive linear correlations with NO 2 and CO while PM 10 maintained a strong positive correlation with PM 2.5 . Interestingly, SO 2 too maintained a significant positive correlation with PM 2.5 , PM 10 , NO 2 , and CO. Previous studies in the Indian city of Mumbai highlighted the strong positive correlation of PM 2.5 with NO 2 and referred to them as a dummy indicator of air pollution due to transport-related emissions in the city [ 44 ]. In the same line, significant positive correlations between PM concentrations and gaseous pollutants, shown by air pollution data, point towards transport-related pollution, solvent evaporation, and waste disposal as sources [ 45 , 46 ].

This study shows PM 10 to have persistent enhancing effects on the number of hospital visits with the respiratory disease during all the cumulative lag days excepting lag 0–2 days. Luong et al. [ 47 ] reported PM 10 and respiratory disease-related hospital admission in polluted Hanoi city of Vietnam. Past studies confirmed the role of PM in inducing oxidative stress in the human respiratory system [ 48 ]. PM 10 impact on respiratory diseases in Delhi may be aggravated due to the road dust fraction of PM 10 that has significant oxidative potential [ 49 ]. It was interesting to note that in multi-pollutant models, the role of PM 10 causing respiratory diseases got subdued due to the combined presence of other pollutants in Delhi city.

This study found that short-term exposure to SO 2 and PM 10 led to increased hospital visits of the city dwellers due to respiratory diseases under (ICD-10) J00-J99. The present study reports the mean SO 2 in ambient air for three years (2016–18) as 14.65 ppb or 38.25 μg m -3 . SO 2 is a very critical gaseous pollutant connected with public health [ 50 ]. Past studies reported that an ordinary person could withstand only 2.62 μg m -3 of SO 2 in the ambient air without any respiratory problem [ 51 ]. However, short but higher concentration exposure to SO 2 gas can cause persistent pulmonary problems [ 52 ]. Orellano et al. [ 53 ], in a more recent and extensive review and metadata analysis, confirmed that short-term exposure to SO 2 , varying from few hours to days, can lead to an increased risk of respiratory morbidity/mortality. Our findings agree with that and found a robust effect of SO 2 on respiratory diseases hospital visits in Delhi. This study shows the robust effect of SO 2 persisted in Delhi throughout the single lag days (from lag0 up lag4) and had an instantaneous (same day, lag 0) increase of 32.6% (RR: 1.326, 95% CI: 1.089, 1.614) of hospital visits. The cumulative concentrations of SO 2 were more robust than the single lag day concentration in Delhi. While every 10 μg m -3 SO 2 concentrations on the same day (lag0) showing 32.59% (RR: 1.326, 95% CI: 1.089, 1.614) rise of hospital visits, the cumulative concentration on the day and its previous day (lag0-1) showing 37.21% (RR: 1.372, 95% CI: 1.107, 1.701) rise in hospital visits which further increased to even 83.33% (RR: 1.833, 95% CI: 1.351, 2.489) rise at a lag0-6 cumulative concentration of the pollutant in Delhi. Ren et al. [ 54 ], using the GAM model, confirmed the SO 2 effect on respiratory diseases in the fast-industrializing Chinese city of Wuhan and found that a 10 μg m -3 rise in SO 2 concentrations led to a rise of RR for respiratory disease mortality by 1.9% at lag0 day or same day. More recently, another two highly industrializing cities of Zhoushan and Hangzhou of China with the comparatively lesser presence of average SO 2 of 6.12 μg m -3 and 17.25 μg m -3 in ambient air, respectively, confirmed the active role of SO 2 in enhancing hospital visits of the patient for respiratory diseases [ 55 ]. Phosri et al. [ 56 ] also reported the effect of SO 2 for hospital admissions for respiratory diseases in industrializing Bangkok city of Thailand.

Recent COVID-19 and air pollution studies in Delhi indicated that even during the rigorous ’lockdown’ period, there was only a marginal decrease of mean SO 2 in the ambient air than in the regular times [ 33 , 57 ]. Therefore, it proves that a significant portion of ambient SO 2 in Delhi is likely to be from non-local origins like distant transfer, fossil fuel-fired thermal power plants in the bordering areas of Delhi, and biomass burning in the neighboring states. India’s recognition as the largest anthropogenic SO 2 emitter replacing China in recent times will be much more worrisome in the context of this study’s findings [ 58 , 59 ].

Suneja et al. [ 60 ], through an experimental study in Delhi, reported the seven-year (2011–2018) mean value of SO 2 level was 2.26 ppb, while this study found a much higher three-year average (2016–18) of 14.65 ppb, indicating the rise of SO concentrations in Delhi in the more recent years. The association of respiratory diseases with PM 10 and SO 2 was found stable in different lag days analyses, indicating the problem’s depth for the city dwellers. The robust and instantaneous nature of the relationship between SO 2 and respiratory morbidity indicated in this study and evidence of similar relationships found in the previous studies highlight the necessity of taking policy-level measures to reduce SO 2 in the ambient air. Limited GAM model application in Indian cities to link air pollution and health effects is not a limitation of the present study findings but rather a call for more sponsored research in the area.

Supporting information

Acknowledgments.

The authors thank the Central Pollution Control Board and the Indian Meteorological Department of Delhi city for providing air pollution and meteorological information, respectively.

Funding Statement

This study was supported by the Graduate School Thesis Grant GCUGR1225632064D, Chulalongkorn University, Bangkok, Thailand. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Research Article

Estimates of air pollution in Delhi from the burning of firecrackers during the festival of Diwali

Contributed equally to this work with: Dhananjay Ghei, Renuka Sane

Roles Formal analysis, Software

Affiliation Department of Economics, University of Minnesota, Minneapolis, Minnesota, United States of America

Roles Conceptualization, Writing – original draft, Writing – review & editing

* E-mail: [email protected]

Affiliation National Institute of Public Finance and Policy, Delhi, India

• Dhananjay Ghei, 
• Renuka Sane

• Published: August 13, 2018
• https://doi.org/10.1371/journal.pone.0200371
• Reader Comments

11 Dec 2018: Ghei D, Sane R (2018) Correction: Estimates of air pollution in Delhi from the burning of firecrackers during the festival of Diwali. PLOS ONE 13(12): e0205131. https://doi.org/10.1371/journal.pone.0205131 View correction

Delhi has had the distinction of being one of the most polluted cities in the world, especially in the winter months from October—January. These months coincide with the religious festival of Diwali. It is argued that air quality gets worse in the aftermath of Diwali on account of firecrackers that get burned during the festival. We use hourly data on PM 2.5 particulate concentration from 2013 to 2017 to estimate the Diwali effect on air quality in Delhi. We improve on existing work by using the event study technique as well as a difference-in-difference regression framework to estimate the Diwali effect on air quality. The results suggest that Diwali leads to a small, but statistically significant increase in air pollution. The effect is different across locations within Delhi. To our knowledge, this is the first causal estimate of the contribution of Diwali firecracker burning to air pollution.

Citation: Ghei D, Sane R (2018) Estimates of air pollution in Delhi from the burning of firecrackers during the festival of Diwali. PLoS ONE 13(8): e0200371. https://doi.org/10.1371/journal.pone.0200371

Editor: Krishna Prasad Vadrevu, University of Maryland at College Park, UNITED STATES

Received: February 4, 2018; Accepted: June 25, 2018; Published: August 13, 2018

Copyright: © 2018 Ghei, Sane. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All data are available from the Central Pollution Control Board, India. See: http://www.cpcb.nic.in/ .

Funding: The author(s) received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Introduction

In 2014, Delhi became the most polluted city in the world [ 1 , 2 ]. Since then it has continued to be in the list of the world’s most polluted cities [ 3 ]. Air pollution is worse in the winter months (October—January) as particles remain suspended in the air for longer duration of time due to the lower temperature, wind speed as well as higher relative humidity. In early November, farmers in the neighbouring states of Punjab and Haryana burn the stubble from the previous harvest to prepare land for the next sowing season, and the smoke is carried to Delhi contributing to the smog [ 4 ].

These winter months coincide with a very important religious festival in India, namely, Diwali. It is argued that air quality gets worse in the aftermath of Diwali, on account of firecrackers that get burned during the festival. The link between firecracker burning and air pollution has been established in other regions (for example, [ 5 ]). This has resulted in calls for banning the sale of firecrackers, and in 2017, the Supreme Court of India did order such a ban.

The question of how much does air pollution increase because of firecracker burning is an important one, because measures such as the ban on the sale of firecrackers impose significant costs in the form of reduced livelihoods of people in the trade.

Existing research on the impact of Diwali on air quality in India has focused on measuring the concentration of pollutants in the air around Diwali [ 6 ], [ 7 ], [ 8 ], [ 9 ], [ 10 ], [ 11 ], [ 12 ], [ 13 ], [ 14 ]. For example, [ 8 ] found Diwali day 24 hour average concentrations, in Lucknow, to be 2.49 and 5.67 times higher when compared with the concentration of pre-Diwali and normal day respectively. In addition, they found SO 2 concentrations to be 1.95 and 6.59 times higher compared to the concentration of pre-Diwali and normal days. [ 7 ] investigated metal concentrations and found that significant amounts of metals released in air contributed to heavy air pollution on Diwali. More recently [ 15 ] analyse PM 10 loads and chemical compounds a few days prior, during and post Diwali and find that firework emissions significantly affect air quality.

However, it is possible that the bad air that we see in Delhi at the time of Diwali is just the bad air quality in winter, and is not causally impacted upon by Diwali. The studies mentioned above make progress on measurement, and show correlations between firecrackers and Diwali, but do not conclusively establish the causal relation between them. The studies also make measurements at local weather stations, but are not able to evaluate the impact on multiple stations within a city at the same time.

In this paper, we use hourly data from 2013 to 2017 to estimate the Diwali effect on air quality, in particular PM 2.5 particulate concentration, in Delhi. We improve on existing work by using the event study technique as well as a difference-in-difference regression framework to estimate the “Diwali” effect on air quality. We find that Diwali leads to a small, but statistically significant increase in air pollution. The effect is different across locations within Delhi. To our knowledge, this is the first causal estimate of the contribution of Diwali firecracker burning to air pollution.

The health implications of poor air quality [ 16 ] [ 17 ] are leading to pressure on the government in Delhi to respond to this crisis. There is a clamour for regulatory interventions that will yield clean air. In January 2016, the Delhi government constituted a policy to restrict cars on roads on certain days (known as the odd-even rule). In the same year, post Diwali, the government declared a public health emergency and shut down schools as well as power plants around Delhi temporarily. In 2017, nine days before Diwali, the Supreme Court of India banned the sale of fireworks in Delhi.

These interventions are often arbitrary and knee-jerk responses to an impending crisis. As a consequence, they have little effects. For example, [ 18 ] show that the 2016 odd—even rule for vehicles was not effective in reducing measurable PM 2.5 pollution in Delhi. Only when we are able to marshal evidence in a systematic way about the extent and nature of the problem, will we be able to design and deliver a response. Estimation is also important as it helps policy makers arrive at a cost-benefit analysis of particular intervention.

The measurement of air pollution in Delhi has begun on a small scale. Granular and high frequency data was made available following 2013 when standardised monitors were placed in different parts of the city to measure pollution levels. Our paper uses the relatively recently available data to contribute to knowledge on air pollution.

Ethics statement

All the meteorological data collected at the five monitoring sites used in this study are publicly available on the internet, and no specific permissions are required to access these sites.

The use of PM 2.5

There are many pollutants in the air such as carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), ozone (O3). The worst among these is small particulate matter, or PM 2.5, a mixture of solid and liquid droplets floating in the air whose diameter is less than 2.5 micrometers. PM 2.5 particles are produced from all types of combustion, including motor vehicles and power plants and some industrial processes.

The health impact from pollution is a complex transform of exposure to all pollutants. However, of the pollutants, PM 2.5 particles are considered the most harmful as they are able to enter deep into the respiratory tract, reaching the lungs. This can cause short-term health effects such as eye, nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath, and in the long-term can affect lung function and worsen medical conditions such as asthma and heart disease. We, therefore, narrow our attention to the measure of PM 2.5. The unit of measurement of PM 2.5 is μ g/ m 3 .

Data sources

We fetch raw PM 2.5 values from two data sources on pollution in Delhi. The first is data from the US Embassy based in Chanakyapuri. The second is from the Central Pollution Control Board (CPCB) that puts out data for various locations across India.

While CPCB has several monitors in Delhi, we selected the four locations that provided us with the most consistent dataset. We thus have data for five locations: 1) R. K. Puram in South West Delhi which is a residential area, 2) Punjabi Bagh in West Delhi, also a residential area 3) Mandir Marg in Central Delhi, 4) US Embassy in the diplomatic enclave in Central Delhi, and 5) Anand Vihar in East Delhi, which is adjacent to an industrial area.

In addition to PM 2.5, we also extract hourly data on wind, temperature and relative humidity for all the locations on the CPCB website . This is in the form of several dropboxes where one has to select the name of the city, and station, the desired time-period as well as the indicators for which data is required. The data on the additional variables is not available for the Chanakyapuri location.

We use hourly data from the locations mentioned above for a time period from January 2013 to May 2017. It should be noted that values are missing from certain sections of the data. These missing observations are excluded from our analysis. We winsorise 1% tail of the observations to remove extreme values.

Fig 1 shows the variation in hourly pollution levels during different days of a week. Darker colors represent increased PM 2.5 matter in the air. Regardless of the day, pollution levels are low during the day, but start increasing post 18:00 hours. and remain elevated till 09:00 hours of the next day. The average PM 2.5 concentration across all days from 18:00 to 09:00 the next day is 140 μ g/ m 3 , whereas the average PM 2.5 concentration from 09:00 to 18:00 is 108 μ g/ m 3 . PM 2.5 levels in the range of 101-200 can cause breathing discomfort to anyone with prolonged exposure to the air during these times.

• PPT PowerPoint slide
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https://doi.org/10.1371/journal.pone.0200371.g001

Fig 2 shows the hourly variation in pollution levels during different months of the year. Note that the scale for this figure is different from that used in Fig 1 . The monsoon months of July—September have the lowest levels of PM 2.5 particulate concentration. Larger particles are settled in few hours due to gravity, but smaller particles such as PM 2.5 are removed by precipitation. Winters have the highest levels of PM 2.5 matter in the air, on account of low wind speed and high relative humidity.

https://doi.org/10.1371/journal.pone.0200371.g002

Fig 3 shows the hourly variation in pollution levels across the five locations. The diplomatic enclave of Chanakyapuri seems to perform better than other areas of Delhi. Anand Vihar in East Delhi has the highest pollution levels amongst the 5 different locations, and has severe levels of air pollution in the night. There is a strong location effect on pollution levels. This can be attributed to varying population densities of these locations as well as the proximity to industries.

https://doi.org/10.1371/journal.pone.0200371.g003

The festival of Diwali

Diwali is an important Hindu religious festival celebrated over a four-five day period. The main day of Diwali is called “Lakshmi Puja”. This is celebrated by the burning of firecrackers, which typically begins around 18:00 hours.

Diwali does not fall on the same date every year as it is based on the Hindu lunar calendar. As a result it is a “moving date” across different years. In the period between January 2013 and May 2017, Diwali occurred on the following dates: Nov 4, 2013, Oct 22, 2014, Nov 11, 2015, Oct 30, 2016.

We estimate the Diwali effect using two methods. The first of these is the event study methodology. This methodology is generally used in the field of finance to measure the impact of a specific event on the value of the firm [ 19 ]. We adopt the same methodology to evaluate the impact of Diwali on PM 2.5 particulate concentration.

The day of the Lakshmi Puja is taken as the event day. We have 4 Diwali events and 4 locations. This gives us a total of 16 events. The Chanakyapuri location is dropped as climate data about this location is not available.

We take the mean of the hourly pollution levels on each date as a proxy for daily series. Next, we calculate the percentage change in PM 2.5 concentration levels by differencing the logarithm of PM 2.5 values. These are then re-indexed to show the cumulative change over a 10 day window.

Next, we perform an hourly event study using the same methodology. Here, we use 1800 hours on the day of Diwali as t = 0 event time. Once again, we have a total of 16 events.

As discussed earlier, it is possible that the bad air that we see in Delhi at the time of Diwali is just the bad air quality in winter, and is not causally impacted upon by Diwali. In early November, farmers in the neighbouring states of Punjab and Haryana burn the stubble from the previous harvest to prepare land for the next season, and the smoke is carried to Delhi contributing to the smog [ 4 ].

Event study

Fig 4 shows the event study on daily data. The solid line represents the average cumulative percentage change in PM 2.5 values during the event window. The dashed line represents the confidence intervals calculated using bootstrapped standard errors. We see that pollution levels start increasing two days before Diwali, and increase till two days after Diwali.

https://doi.org/10.1371/journal.pone.0200371.g004

Fig 5 shows the event study on hourly data. The event time ( t = 0) is 1800 hours on the day of Diwali across four Diwali events and four locations. As earlier, the solid line represents the average cumulative percentage change in PM 2.5 values during the event window and the dashed lines represent the 95% confidence intervals calculated using bootstrapped standard errors. We see that the pollution levels do not rise before 1800 hours and post the event time there is a statistically significant increase in pollution levels that rise up to approximately 100% in a short span of 5 hours.

https://doi.org/10.1371/journal.pone.0200371.g005

Table 1 shows the regression results for four different models. Robust clustered standard errors are used throughout. The first model (Column 1) contains only hour effects along with location fixed effects. The second model (Column 2) contains hour and month fixed effects. The third model (Column 3) contains meteorological factors as well and the fourth model (Column 4) contains only meteorological factors.

https://doi.org/10.1371/journal.pone.0200371.t001

The two competing models we have is the second (Column 2) and fourth model (Column 4). While the fourth model only accounts for climate factors, the second model accounts for hour and month effects. Since, climate is correlated with the months, the months capture not only the variation due to climate but also captures variation due to other exogenous factors such as stubble burning in the neighboring states of Punjab and Haryana which is a common trend during late October and early November. Given the fine granularity of the data set, model 2 is more representative as it captures not just meteorological factors but also other exogenous factors.

The coefficient on the constant term is the average pollution in Anand Vihar. This is quite high, and as seen in Column (2) was an average of 340 μ g/ m 3 . The other three locations have lower pollution levels on average relative to Anand Vihar.

The coefficient on the Diwali dummy reflects the Diwali effect at Anand Vihar. It is positive and statistically significant across the four different models. The average particulate concentration is 15.7 μg / m 3 higher. This is suggestive of the fact that there is certainly a rise in pollution levels in Delhi during Diwali. While this may seem relatively small, it is useful to remember that this is on a base of already high pollution (>300 μ g/ m 3 ).

There is a differential effect on Diwali in other locations relative to Anand Vihar on Diwali. For instance, Diwali adds on an average 61.81 (77.504-15.692) μ g/ m 3 PM 2.5 particulate concentration in the air at Mandir Marg relative to Anand Vihar.

Fig 6 shows the estimated marginal effect of Diwali on air pollution levels using Model 2 and Model 4 in Table 1 . The effect is the conditional expectation of the PM 2.5 value on different locations during Diwali keeping the other regressors as constant (for categorical variables) and as average (for continuous variables). The figures show that there is an increase in pollution levels during the day of Diwali compared to the control group. The trend is same across all four locations. Tighter confidence intervals suggest that the increase is statistically significant.

https://doi.org/10.1371/journal.pone.0200371.g006

It is possible that our results are confounded by fireworks that persist after the Diwali days. We, therefore, also conduct regressions by taking only pre-Diwali days as our control group as a robustness check. In particular, we take 10 days prior to Diwali every year as our control group. We estimate Model 2 and Model 4, and find that the results are as expected and we see that there is an increase in PM 2.5 concentration during Diwali. Results for this regression are available upon request.

One might argue that given the fact that the Diwali effect is sustained for more than 2 days as seen in event study on daily data ( Fig 4 ) this would mean that we are underestimating the impact of Diwali as the control group has on average higher pollution levels since it contains days post Diwali.

We, therefore, divide the Diwali events by months, and use as control groups the same months of the non-Diwali years. Out of the four Diwali events, two of them were in October and two of them were in November. Consider for example, Diwali was in November for 2013 and 2015, thus, we use the control group as November of 2014 and 2016. If the hypothesis is correct, the effect of Diwali should increase since we are now measuring the control group more accurately.

Table 2 shows the regression for October and November. For October, we see an increase in the effect of Diwali when we change the control group. However, this impact is not visible when we consider November.

https://doi.org/10.1371/journal.pone.0200371.t002

Fig 7 shows the estimated effect of Diwali compared to the control group for October and November. The only thing surprising in this case is Anand Vihar where the pollution levels on Diwali are lower compared to the control group. This may be because Anand Vihar is located near the industrial area. Industrial activity comes to a halt before Diwali as workers have holidays which would mean that the pollution from industries is not accounted for and hence, the effect is actually lower compared to the control group.

https://doi.org/10.1371/journal.pone.0200371.g007

Very little is known, at present, about the causal impact of Diwali on air quality. We have begun analysing this question here. Our results suggest that there is a strong location and month effect when examining air quality. Winter months see some of the worst air pollution levels in Delhi. We find that Diwali, on average, leads to increasing pollution levels across all locations in Delhi. Over a period of two days, Diwali adds about 40 μ g/ m 3 to PM 2.5 particulate concentration. While this number may look small in itself, it is high considering the already poor air quality around the time. There is a wide variation in the effect of firecrackers across locations. It is further important to study the contribution of firecrackers relative to vehicles at the same time. We hope to address this in future research. We also hope that the current study contributes to the cost-benefit analysis of proposed policy measures to reduce air pollution.

• 1. TOI. Delhi has the worst air pollution in the world: WHO; 2014. The Times of India, 7 May 2014.
• 2. Chauhan C. Delhi world’s most polluted city: Study, Hindustan Times, 8 May 2014; 2014. https://www.hindustantimes.com/india/delhi-world-s-most-polluted-city-study/story-Kqiz2WDZ8muWya6MJpbGPM.html .
• 3. NUMBEO. Pollution Index 2018. https://www.numbeo.com/pollution/rankings.jsp .
• View Article
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• 14. Devara P, Alam M, Dumka U, Tiwari S, Srivastava A. Anomalous Features of Black Carbon and Particulate Matter Observed Over Rural Station During Diwali Festival of 2015. In: Environmental Pollution. Springer; 2018. p. 293–308.

Delhi world's 'most polluted' capital: report

• Published 20 March

Delhi struggles with bad air round the year

Delhi was the most polluted capital city in the world in 2023, a Swiss-based air-quality monitoring group has found.

India, of which Delhi is the capital, was also ranked as the world's third-most polluted country after neighbours Bangladesh and Pakistan, IQAir said.

The country's air has worsened since 2022, when it was the eighth most polluted country, it added.

Air pollution is a serious problem in several Indian cities.

Experts say that rapid industrialisation coupled with weak enforcement of environmental laws have played a role in increasing pollution in the country.

India has seen a lot of development in the past few decades, but poor industrial regulation means that factories do not follow pollution-control measures. Rapid construction has also contributed to rising levels of pollution.

The report by IQAir said that India's average level of PM2.5 - fine particulate matter that can clog lungs and cause a host of diseases - was 54.4 micrograms per cubic metre.

Globally, air that has 12 to 15 micrograms , external per cubic metre of PM2.5 is considered safe to breathe, while air with values above 35 micrograms per cubic metre is considered unhealthy.

Delhi's air quality was worse than India's overall air quality with the city having a PM2.5 reading of 92.7 micrograms per cubic metre.

Delhi struggles with bad air around the year, but the air gets particularly toxic during winter.

This happens due to various factors, including burning of crop remains by farmers in nearby states, industrial and vehicular emissions, low wind speeds and bursting of firecrackers during festivals.

Last year, the government shut schools and colleges for several days in a row due to the toxic air.

Meanwhile, the northern Indian city of Beguserai and the northeastern city of Guwahati were ranked as the two most polluted cities in the world.

Only seven countries met the World Health Organization (WHO)'s annual PM2.5 guideline, which is an annual average of 5 micrograms per cubic metre or less.

These include Australia, New Zealand, Iceland and Finland.

According to IQAir, this data was gathered from more than 30,000 air quality monitoring stations positioned in 134 countries, regions and territories.

Read more India stories from the BBC:

Foreign students attacked in India over Ramadan prayers

New India election to be held in seven stages

Lottery firm tops list of India's political donors

Water crisis shakes India’s Silicon Valley

The cruel Yale benefactor who traded in Indian slaves

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• Air pollution

More on this story

Why is India's pollution much worse than China's?

• Published 6 November 2019

No school, no play as air pollution chokes Delhi

• Published 6 November 2023

Air Pollution in Delhi | Causes, Effects, Stats, Pollution Level & Control Measures Essay & Articles

What is air pollution in new delhi.

Air pollution is nothing but, increase of toxic and harmful material in the air, resulting in contamination of air. These material may be in form of solid, liquid or gaseous substances and released in air due to various activities by human beings causing an adverse effect to natural life.

Delhi is National Capital of India, an Union Territory, but since few years Capital of India is counted as the most polluted state in the country.

Delhi is a city which accommodates more than 170 lakhs people. Air pollution has become such a big issue in the city that government had to shut down schools and colleges due to fear of certain respiratory diseases. People were warned to not to step out of their houses for certain days.

There have been reports of high number of deaths due to the such a poor quality of air. Adding to this the changing whether conditions make it even worse by locking the pollutants in the air. People are depending on air purifying masks and machines to consume the most basic Oxygen.

Delhi’s air pollution are headlines every winter. This is mainly due to air pollutants carried from other states like Punjab and Haryana, where burning of crops is carried out.

Although many steps have been taken to solve this problem of pollution. It is just prohibiting certain activities which lead to air pollution, depending on the circumstances at that moment of time. Therefore giving a temporary solution, but this issue need a permanent solution to limit the bad quality of air enter into the atmosphere.

This requires a constant monitoring and preventive steps to minimize the dangerous pollution levels.

There are many causes which contribute to such a massive pollution which results in serious health hazards and even death of human beings and depletion of other natural life.

Several studies have concluded that petrol, diesel, burning coal, industrial waste, burning firecrackers etc contribute highly to pollution.

Causes of Air Pollution in Delhi

There are many reasons for such a massive air pollution in Delhi. These are:

• One of the main reason is crop burning. The neighbouring states Haryana and Uttar Pradesh, burn the rice subtle every year after harvest. The smoke from the burning is directed towards Delhi. All the pollutants get locked in the atmosphere which is already polluted.

The farmers do this to reduce cost and time as the burning of crops after the harvest can be done in no time and the field can be made ready for the next harvest easily. This is done in the month of October and November and by the time winter comes the pollutants get trapped in the wet and cold air leading to development of smog.

The agricultural department has laid a ban on this practice but some farmers still continue with this practice.

• Delhi being one of the major cities is highly populated with number large number vehicles, which cause traffic and pollution. Vehicle emissions contribute a huge amount of pollution. This is because of burning of diesel and petrol and lack of green cover around the city.

Past few years there have been tremendous increase in number of vehicles causing traffic and air pollution. This also happens due lack of public transport, public is forced to get their own vehicles and there is no regulation on the pollution caused by these vehicles.

• As said earlier Delhi is becoming over populated day by day, construction of new buildings. The cement, wood dust and other dust particles that arise from construction sites spread allover and mix in air as small particles.

To give space to more construction sites, trees are being chopped off, which play a major role in controlling pollution. Over population also leads to more garbage dumping and to add to it these garbage dumps are being burned where ever possible, leading to more smoke in the air.

4) Industrial pollution is also one of the culprit, which contributed in Air Pollution in Delhi . Factories in and out of city area release very harmful and toxic chemicals in air and nearby water bodies. According to sources, Power plants and the famous Badrapur thermal Power Station contribute around 80% to 90% of pollution.

• Diwali which comes at the start of winter, at the same time when crops are being burned, cause tremendous amount of smoke. With the burning of fire crackers, wood and crops simultaneously cause heavy smog and suffocating environment. The cold and damp weather add fuel to fire to the situation making it more worse.

Effects of Air Pollution in Delhi

Air pollution leads to many health problems, the lack of pure air to breathe is a major concern in the present era. Indian Medical Association has warned public to retrain themselves form going out and declared a “Public Health Emergency” in Delhi, couple of years back. People started wearing masks to protect themselves from inhaling hazardous gases present in the air.

There are many health risks associated with air pollution, such as:

⦁Respiratory problems, like dry cough, wheezing, sinusitis, sore throat, breathlessness etc.

⦁Threat to lung functioning, reduced lung capacity, lung cancer.

⦁Head aches, eye irritation.

⦁Heart diseases. Certain gasses prevent oxygen in blood and this can lead to reduction in supply of oxygen to heart, Asthama.

⦁Premature birth or birth defects in certain cases.

Preventive Measures to Stop the Effect of Pollution

Many preventive measures have been introduced by government to protect oneself from these harmful effects. One should avoid going for walking or jogging early in the morning, try not to smoke cigarettes or burn anything, use a mask as much as possible to prevent you from inhaling the hazardous gasses, plant as much as tress and plants such as aloe Vera, ivy etc.

Consume fruits rich in Vitamin C, magnesium, drink lots of water. Install best air purifiers at home or air purifiers at office, try car pool if possible to reduce traffic and vehicle pollution and last but not the least seek medical help immediately if you notice any of the problems.

Pollution Level in Delhi

The Air Quality Index(AQI) level at 100 is considered as normal, but in Delhi the AQI is 267, which is considered as unhealthy and fall under “poor” range .

The smog effects the visibility of vehicles causing accidents at highways, cancellation of flights and trains. Substances such as copper, magnesium, Nickel, Zinc form major sources of particles polluting the air.

The poisonous particulate matter (PM 25) is less than 2.5 microns, which can easily go into the lungs of an individual. Medical experts say the levels of pollution in the city is equal to smoking 50 cigarettes in a day.

The air quality in Delhi has deteriorated to such a level that it is hazardous to health.

Air Pollution in Delhi Statistics

According to Environment pollution(Prevention and control) Authority(EPCA) of 2017-18, the air quality showed the signs of improvement, but it is not close to safe yet.

In Nov 2018, the air quality was at its worst, touching the “Severe plus emergency”. The AQI levels reached above 300.

Experts say if this continues, Delhi will be the worst city and most polluted city in the world. Air quality index is generally observed moderate between January to September, then it drastically changes to Poor/severe or even hazardous in the months of October to December and this is mainly because of burning of crops, firecrackers and cold and damp weather.

According to sources 36% of Delhi’s pollution comes form the city itself, 34% from NCR area and remaining from neighbouring states or even international borders.

Control Measures to Reduce Air Pollution in Delhi

While the government is taking many steps to control the pollution and its effects. These steps are to be taken urgently to reduce the pollution, as it is causing serious health effects to citizens and all natural life.

Here are the steps taken by the authorities to solve the situation:

• The first and foremost step is to plant more trees. The fresh can help in reduce the pollution and emit healthy gasses.
• Pollution check of all the vehicles by transport department, and encouraging fuel efficient cars.
• Encourage car pool or public transport to help reduce flow of more vehicles on roads. Citizens should take initiative for car polling with their friends and family. This will also help in traffic control. To discourage public from using their own vehicles authorities have decided to raise the parking fees.
• Burning of any garbage or leaves or wood is being prohibited. Ban on Fire crackers is being implemented on the day of Diwali.
• Halt on all the construction activities. This will also mean ban on all stone crushers, diesel generator sets, to prevent the dust coming from the activities.
• Mechanical sweepers and water sprinklers have been introduced, to clean the roads.
• 7) Air purifiers in offices are being installed even home owners are encouraged to install purifiers in their homes to cope up with the bad air.
• Long term measures such as ban on burning and sale of firecrackers completely. The Badrapur thermal Power plant to be shut down as soon as possible, which causes lot of pollution by emitting hazardous gasses.

Air Pollution and Water Pollution are a major rising concern in Delhi and many parts of India. In the recent years, Delhi has suffered the most due to air pollution.

Many kids and adults had to face serious health issues due to air pollution and bad quality of air. There have been reports of deaths too. Solving this situation is both in the hands of government as well as public.

If this situation continues it is going to lead to many health hazards among all ages including pregnant women and unborn kids. Many dangerous gasses such as hydrocarbons, nitrogen dioxide, sulphur are being released.

The quality of air in Delhi was so bad that it resulted in cancellation of cricket test match, this was first time in Indian history where a match was cancelled due to pollution as the players were not able to stand in the polluted air in the stadium, making it even difficult to breathe.

Despite many measures by government, the air quality is not improving in any manner rather it deteriorates every season. This is due to public and relevant authorities are not co-operating.

The burning of crops happens every year despite many restrictions, as the farmers feel it is the cheap way to destroy the residue. They should be given proper guidance and other steps to tackle this.

Although burning of crops is common in may states but Delhi has been affected the most due the others factors and as the pollution was already high in the state moreover, this happens at the start of winter or during winter making it more worse.

Government should also take measures to control number of industries around the city limits and also strict laws should be made to control pollution.

The pollution or smog levels must be understood and solved for coming years, so that this situation does not repeat again. Educating public about pollution and steps to  tackle would help in reducing the pollution to a great extend.

Also Read :

10 Causes of Air Pollution

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Delhi Air Pollution

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Delhi Air Pollution: Delhi, a bustling metropolis, stands at a critical juncture in its battle against air pollution. This urban giant, attracting masses for its vibrant lifestyle and opportunities, now grapples with a health crisis fueled by deteriorating air quality. From cardiovascular diseases to respiratory disorders, the city’s air pollution contributes significantly to escalating health risks and premature mortality rates.

Delhi pollution measures: Despite the World Health Organization’s (WHO) guidelines for healthy air, Delhi’s air quality often falls short, posing a stark contrast to global standards. With data spanning over 7,300 cities worldwide, Delhi’s air pollution scenario is not just a local issue but a global concern. Dive into this comprehensive guide to understand the depth of Delhi’s air pollution crisis and the measures being taken to combat it.

Table of Content

Delhi – World’s Most Polluted City

Why delhi is the most polluted city in the world, analyzing delhi’s air pollution: data and statistics, government initiatives to combat air pollution in delhi, public health impacts of air pollution in delhi.

Pollution Control in Delhi: The global air quality report, conducted by the State of global air (SoGA) initiative, has announced the cities with the highest exposure to poor air quality. This SoGA publication offers insights into the levels of pollution in various cities across the globe. For the fourth consecutive year, Delhi has maintained its position as the world’s most polluted city, with an annual average PM2.5 concentration of 92.6 micrograms per cubic meter. Additionally, Delhi has also stood second on the list of the world’s most polluted capital cities among 116 capital cities.

While the WHO suggested ideal annual PM2.5 levels of 5 μg/m3, Delhi recorded an average annual PM2.5 level of 92.6 μg/m3 in 2022. According to the report, Lahore, Hotan (China), and Bhiwadi (Rajasthan) ranked as the most polluted cities in the world. While Lahore recorded PM2.5 levels of 97.4 μg/m3 with the worst air quality, Hotan and Bhiwadi had PM2.5 levels of 94.3 and 92.7 μg/m3, respectively.

In November 2019, the Supreme Court of India declared that Delhi has become worse than “narak (hell)” and suggested using explosives to kill everyone. During the COVID-19 pandemic lockdown, water quality in the Yamuna and Ganges river basins improved due to industry closures. However, air quality has also significantly improved during this time. India’s Ministry of Earth Sciences published a research paper in October 2018 attributing almost 41% of vehicular emissions, 21.5% to dust, and 18% to industries.

Read: Air Pollution

Air pollution health effects: Delhi’s air pollution problem is attributed to animal agriculture, as Delhi smog and other harmful particles have been produced by farmers burning their crops in other states since the 1980s. Initiatives such as the Great Green Wall of Aravalli green ecological corridor are being considered to combat pollution.

• In December 2019, IIT Bombay, in partnership with the McKelvey School of Engineering of Washington University in St. Louis, launched the Aerosol and Air Quality Research Facility to study air pollution in India.
• Poor air quality in Delhi is primarily caused by motor vehicle emissions, wood-burning fires, cow dung cake combustion, agricultural land fires, diesel generator exhaust, construction dust, garbage burning, and illegal industrial activities.
• Despite being kerosene-free, 10% of households use wood, crop residue, cow dung, and coal for cooking. Fire in Bhalswa landfill is another major cause of airborne particles in Delhi.

Court-ordered restrictions on bus service in Delhi have exacerbated the large contributions of vehicles and road dust to air pollution.The Delhi government has implemented measures to address the poor air quality in the city, including reducing staff tenures, advising staff to reconsider bringing their children to Delhi, providing high-end air purifiers, and installing expensive air purifiers in their offices. The Air Quality in Delhi index reached 465 on 14 November 2021, leading to the closure of all educational institutions for a week.

The Commission for Air Quality Monitoring (CAQM) directed that schools, colleges, and educational institutions will be closed until further notice. In addition, trucks have been banned, construction activities have been halted until 21 November, and 6 out of 11 thermal power plants in Delhi have been shut down until 30 November. The Delhi government plans to add 1000 extra CNG buses and randomly check registrations and pollution certificates of cars to curb pollution. Diesel cars above 10 years and petrol cars about 15 years old are banned due to pollution. The Supreme Court of India has suggested that government officers living in government colonies should commute by car pooling together or by public transport.

• Types of Environmental Pollution and their Causes
• Air Pollution Control

Current Pollution Levels

• As of [latest data year or month], Air Quality in Delhi index (AQI) frequently oscillates between ‘very poor’ and ‘severe’ categories, especially during winter months. For instance, in [specific month/year], the AQI reached alarming levels of over 300, categorizing the air quality as hazardous.

Historical Trends

• Over the past decade, Delhi has seen a consistent rise in pollution levels. Data from the Central Pollution Control Board (CPCB) indicates a [percentage] increase in particulate matter (PM2.5 and PM10) since [specific year].

Comparative Analysis

• Compared to other major cities in India, Delhi often records the highest pollution levels. For instance, in [specific year], Delhi’s average PM2.5 concentration was about [specific value], significantly higher than cities like Mumbai and Bangalore.

Seasonal Variations

• The pollution levels in Delhi show marked seasonal variation. Post-monsoon and winter months (October to January) typically record the highest pollution levels due to factors like stubble burning, firecrackers during festivals, and meteorological conditions.

Impact of Lockdowns and Restrictions

• The lockdowns due to the COVID-19 pandemic saw a temporary improvement in air quality. For example, during the initial lockdown phase in [specific month/year], the AQI improved by [percentage] compared to the same period in the previous year.

Global Comparison

• When compared globally, Delhi often ranks among the top cities with poor air quality. According to the World Health Organization (WHO), Delhi’s air pollution levels are several times higher than the safe limits set by the organization.

Introduction to Government Efforts

• The government has implemented several initiatives to tackle the escalating air pollution crisis in Delhi. These efforts aim to reduce emissions, improve air quality, and safeguard public health.

Key Initiatives

• Odd-Even Scheme : A traffic rationing measure to reduce the number of vehicles on the road.
• Ban on Crop Burning in Neighboring States : Enforcement of regulations to prevent crop residue burning, a major contributor to Delhi’s air pollution.
• Promotion of Electric Vehicles : Incentives for electric vehicles to reduce vehicular emissions.
• Installation of Smog Towers : Setting up smog towers to filter and purify the air.
• Green Cover Expansion : Initiatives to increase green spaces in and around Delhi.

Impact Assessment

• While these Delhi pollution measures have shown some positive outcomes, continuous monitoring and adaptation of strategies are essential for long-term improvement in air quality.

Read: World Air Quality Report 2023

Understanding Health Risks

• Prolonged exposure to polluted air in Delhi poses significant health risks to its residents, affecting all age groups.

Major Health Concerns

• Respiratory Issues : Increased cases of asthma, bronchitis, and other respiratory disorders.
• Cardiovascular Problems : Heightened risk of heart attacks and strokes due to poor air quality.
• Impact on Children’s Health : Children are particularly vulnerable, with air pollution affecting lung development and causing frequent respiratory infections.
• Long-Term Effects : Chronic exposure can lead to severe health issues like lung cancer and reduced life expectancy.

Preventive Measures

• Recommendations for residents include using air purifiers, wearing masks, and minimizing outdoor activities during high pollution days.

Read: Strategies to Control Environmental Pollution

The ranking of Delhi in terms of pollution has always been a matter of significant concern and attention, both nationally and internationally. The city has been ranked 4th on the list of the World’s Most Polluted Cities 2022 and has been facing severe air quality challenges impacting the health and quality of life of its residents. Effects to address this issue have included policy initiatives and increased public awareness. While rankings may alter, the ultimate focus remains on creating a cleaner and more sustainable future for the residents of Delhi and its environment as a whole.

FAQs on Delhi Air Pollution

1. what makes delhi the most polluted city in the world.

Delhi’s air pollution is attributed to factors like motor vehicle emissions, wood-burning fires, agricultural land fires, and industrial activities.

2. How does Delhi’s air quality compare to WHO guidelines?

The WHO suggests ideal annual PM2.5 levels of 5 μg/m3, but Delhi recorded an average annual PM2.5 level of 92.6 μg/m3 in 2022, far exceeding these guidelines.

3. What impact did the COVID-19 pandemic have on Delhi’s air quality?

During the COVID-19 lockdown, Delhi saw a temporary improvement in air quality due to reduced industrial activity and vehicular traffic.

4. What measures has the Delhi government taken to improve air quality?

The Delhi government has implemented measures like reducing staff tenures, advising staff to reconsider bringing their children to Delhi, providing high-end air purifiers, and installing expensive air purifiers in their offices.

5. What are the health impacts of air pollution in Delhi?

Pollution in Delhi is linked to health problems such as cardiovascular issues, respiratory disorders, type 2 diabetes, and respiratory infections, contributing to premature mortality rates.

6. What are some of the initiatives to combat pollution in Delhi?

Initiatives include the Great Green Wall of Aravalli green ecological corridor and the Aerosol and Air Quality Research Facility launched by IIT Bombay and Washington University.

7. How does the Supreme Court of India view Delhi’s pollution situation?

The Supreme Court of India has expressed severe concern about Delhi’s pollution, suggesting measures like carpooling and public transport for government officers to reduce pollution.

8. What are the consequences of Delhi’s air pollution on public health?

The consequences include a prevalence of diseases such as cardiovascular issues, respiratory disorders, type 2 diabetes, and respiratory infections, leading to increased mortality rates.

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Air pollution in Delhi-NCR

Syllabus: Conservation, environmental pollution and degradation, environmental impact assessment

Source: Indian Express , Indian Express , DTE , Indian Express

Context : Delhi pollution: From late October onwards, meteorological factors and ‘stubble’ burning to add to the already high pollution base in the Indo-Gangetic basin, particularly the pollution due to the  Particulate Matter (PM), Haze and Smoke.

Particulate matter (PM ) is made of solid particles and liquid droplets in the air. Any type of burning or dust-generating activity is a source of PM E.g., Emissions (from vehicles and industrial plant smokestacks)

Particulate matter— PM2.5 (diameter of 2.5 micrometres or less) and PM10 —far exceeds national and World Health Organization limits and are considered the main culprit for high pollution of Delhi and its surrounding regions called NCR.

Reasons for Delhi NCR region facing extreme particulate pollution:

Geographical reasons:

• Location of Delhi : It lies to the northeast of the Thar Desert, to the northwest of the central plains and to the southwest of the Himalayas. As winds arrive from the coasts, bringing with them pollutants picked up along the way, they get ‘trapped’ right before the Himalayas.
• Cold temperature during winter : During summer hotter air rises higher above the surface and takes the pollutants along with it. However, during October-November, the air is not that hot. The pollutants are trapped and tend to get concentrated at lower levels of the atmosphere, resulting in the smoke and haze situation.
• Lack of wind esp. after the end of the monsoon : Average wind speed in winter in the Delhi NCR region is one-third of the summer months. This makes the pollutant concentration in the region.
• Dust Storm: -According to SAFAR (System of Air Quality and Weather Forecasting And Research), 40% of the particulate pollution in Delhi on those specific days could be sourced to a “multi-day dust storm” that originated in the Middle East.

Anthropogenic factors:

• Stubble burning : The root cause of stubble burning can be traced back to the 1960s-70s when India introduced several measures as part of its Green Revolution to feed its rising population.
• Governmental policy: In an attempt to address the growing water crisis, the Punjab and Haryana governments introduced laws, which delayed Kharif cropping and thus worsened the pollution due to stubble burning.
• Manufacturing activity, Power Generation, Construction, and Transport: The Central Pollution Control Board (CPCB) and the National Environmental Engineering Research Institute (NEERI) have declared vehicular emission as a major contributor to Delhi’s increasing air pollution.
• Minimum Citizen participation : Unlike in other parts of the world, there is little citizens’ movement for controlling pollution.
• Poor Regulations : Regulation is most often seen as imposing bans, not hand-holding and persuading industry – most of them small factories – into adopting environment-friendly measures
• India has not recognised in policy and law that air pollution is a killer.
• On Adult: The Lancet report that had said that 12.5 per cent of deaths in India occurred due to air pollution
• On children: More than 116,000 infants in India died within a month of birth in 2019 due to air pollution — outdoor and indoor — according to the State of Global Air 2020 report.
• On Mother : Studies say that because of exposure of the pregnant mother to very high pollution levels, actually affects the placenta and the foetus.
• On Education : Lost hours due to the closure of schools e.g. Severe air pollution in Delhi has led to the closure of the primary school.
• On Economy : Closure of industries/factories. Limits on the construction activity etc.

Steps Taken by the government

• Graded Response Action Plan (GRAP): In pursuant to the Supreme Court’s order in the matter of  C. Mehta vs. Union of India (2016) regarding air quality in the National Capital Region of Delhi, a Graded Response Action Plan has been prepared for implementation under different Air Quality Index (AQI) categories namely, Moderate & Poor, Very Poor, and Severe.
• National Clean Air Programme (NCAP)- It has the goal of reducing the concentration of coarse (PM10) and fine particles (PM2.5) in the atmosphere by at least 20% by the year 2024, with 2017 as the base year for comparison.
• In-situ solutions include Turbo happy seeders and bio-decomposers, while the  ex-situ solutions  include collecting and using stubble as fuel in boilers, to produce ethanol, or simply burning away alongside coal in thermal power plants.
• Other measures : mobile enforcement teams to check vehicular pollution, public awareness campaigns, investment in mass rapid transport systems, and phasing out old commercial vehicles.
• Delhi’s “Green War Room” signalling the fight against the smog, is analyzing satellite data on farm fires from Punjab and Haryana to identify and deal with the culprits.
• Cleaner transport: The government’s recent push for electric vehicles shows promise, while the response of industry and the buy-in from customers will be key.
• Better farming practices- Needed is the political will to act, as poor farmers complain that they receive no financial support to dispose of post-harvest stubble properly.
• The Indian Agricultural Research Institute has proposed a low-cost way to deal with the problem of stubble burning by spraying a chemical solution to decompose the crop residue and turn it into manure. Better coordination is needed  

Facing a growing environmental and health calamity, antipollution efforts are being strengthened. But to succeed, the different levels of government must harness the political will to invest more, coordinate across boundaries, and motivate businesses and residents to do their bit.

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Air Pollution

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Q. How is air pollution measured and tracked in India? What are the recent changes introduced to air pollution measurement? (15M)

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In the context of WHO Air Quality Guidelines, consider the following statements ( UPSC 2022)

• The 24-hour mean of PM2.5 should not exceed 15 ug/m3 and the annual mean of PM2.5 should not exceed 5 ug/m3.
• In a year, the highest levels of ozone pollution occur during periods of inclement weather.
• PM10 can penetrate the lung barrier and enter the bloodstream.
• Excessive ozone in the air can trigger asthma.

Which of the statements given above is correct?

(a) 1, 3 and 4

(b) 1 and 4 only

(c) 2, 3 and 4

(d) 1 and 2 only

As per the new guidelines recommended air quality levels by WHO (revised after 16 years), the 24-hour mean of PM2.5 should not exceed 15 ug/m3 and the annual mean of PM2.5 should not exceed 5 ug/m3. The highest levels of ozone pollution occur during periods of sunny weather and not during inclement weather. PM 2.5 can penetrate the lung barrier and PM 10 can only lodge inside the lungs. Excessive ozone in the air can cause breathing problems, trigger asthma, reduce lung function and cause lung diseases.

Which of the following are the reasons/factors for exposure to benzene pollution?  (UPSC 2020)

• Automobile exhaust
• Tobacco smoke
• Wood burning
• Using varnished wooden furniture
• Using products made of polyurethane

Select the correct answer using the code given below:

(a) 1, 2 and 3 only

(b) 2 and 4 only

(c) 1, 3 and 4 only

(d) 1, 2, 3, 4 and 5

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Delhi's air quality turns 'poor'; experts cite unfavourable weather

The poor air quality is largely credited to unfavourable meteorological conditions and forest fires in neighbouring states..

Listen to Story

• Delhi's air quality dips to 'poor' category due to unfavourable weather conditions
• Average Air Quality Index (AQI) rose to 243 on Wednesday
• Commission for Air Quality Management convenes review meeting after deterioration in air quality

Delhi experienced a significant deterioration in air quality as it dipped to the 'poor' category on Wednesday due to unfavourable meteorological conditions and forest fires in neighbouring states, the Central Pollution Control Board (CPCB) said.

The city's 24-hour average air quality index (AQI) rose to 243 by 4 pm, prompting the Commission for Air Quality Management (CAQM), a statutory body tasked by the Centre with planning and implementing air pollution reduction strategies in Delhi-NCR, to convene a review meeting with experts from the India Meteorological Department (IMD) and Indian Institute of Tropical Meteorology.

The 24-hour average AQI noted on Sunday was 183 in the 'moderate' category, after which the index entered the 'poor' category with a reading of 227 on Monday and 234 on Tuesday.

At the review meeting, the experts told the CAQM panel that the wind direction and speed are rapidly changing due to high convection rate and completely dry conditions, along with high temperatures, are leading to continued suspension of dust over the region.

They noted that the high incidence of agricultural residue burning in and around NCR areas and forest fires in the adjoining states could also be impacting the overall air quality of the region.

The CAQM directed air pollution control bodies in NCR and other agencies concerned to conduct intensive drives at major pollution hotspots in the region focusing on dust abatement measures. It also asked them to augment the number and frequency of water sprinklers and mechanical road sweeping equipment in the region.

The commission also instructed them to closely monitor fire incidents and open burning of municipal solid waste, as well as to intensify enforcement of dust control measures at construction and demolition project sites.

In addition, flying Squads of CPCB will also intensify inspections for appropriate action against sites, and projects flouting the statutory directions of the commission.

IN THIS STORY

• Air Conditioners
• Washing Machines
• Vacuum Cleaners
• Ceiling Fans
• Water Heaters
• Water Purifiers
• Refrigerators
• Mixers & Grinders
• Food Processors
• Gas Stoves & Induction

Delhi Air Pollution Case Study (2022) Essay & Statistics

Does this photograph need any introduction? Yes. It is India Gate, an iconic monument in Delhi. See how beautiful it looks.

Here is a contrasting image of the same monument taken recently.

The monument is the same. But, it is not visible clearly because of air pollution. Delhi has been notorious for its miserable air quality. The Air Quality Index (AQI) has been consistently bad for more than five to six years. Even today (November 30, 2022), it is unhealthy.

Source – https://www.iqair.com/in-en/india/delhi

An AQI of 198 is unhealthy, even early in the morning. But, then, the AQI starts climbing quickly and reaches more than 300 almost daily, with specific areas crossing 350. That can become unnerving. The data for the past four days should put things in proper perspective. 

This article discusses air pollution in the Indian national capital in 2022 to understand why it ranks among the world’s most polluted cities. We shall examine and analyze the reasons for Delhi’s air pollution and look at remedial measures to keep the pollution levels under check.

The Primary Causes of air pollution in Delhi

PM2.5 is the leading cause of air pollution in Delhi. The PM2.5 concentration in Delhi currently is 29.5 times the WHO annual air quality guideline value.

• PM2.5 Pollution

Various factors contribute to PM2.5 pollution in Delhi. Studies have shown that more than 65% of Delhi’s winter pollution load is because of external factors. The pollution source is from outside Delhi’s geographical boundaries. The burning of agricultural biomass in the neighboring states of Punjab, Haryana, and Uttar Pradesh is primarily responsible for Delhi’s pollution. Generally, farmers burn agricultural stubble at the end of every harvesting season to refresh the soil before the start of the next season. 

However, stubble burning is not Delhi’s only source of PM2.5 air pollution. Besides agricultural pollution, Delhi air has to contend with vehicular emissions, industrial pollution, and other issues.

The Center for Science and Environment has analyzed data from various sources to conclude that vehicular emissions contribute to 51% of PM2.5 levels in Delhi. Residential sources contributed to 13%, whereas 11% is due to industrial pollution. Construction activity is responsible for 7% of PM2.5 pollution, followed by the energy sector and the burning of waste at 5%. Road dust accounts for around 4% of PM2.5 pollution.

The analysis confirmed that Delhi’s local sources accounted for 32.9% of the total pollution in the city. Other sources contributing to Delhi’s PM2.5 levels constitute the NCR districts (32.8%), other state districts (25.8%), and biomass burning in Punjab-Haryana-Uttar Pradesh (9.5%).

Traffic congestion in the city contributed to high NO2 levels in the environment. The maximum NO 2 levels were seen in the evenings when the congestion was at its highest. The hourly NO 2 levels were around 76 µg/mg 3 to 86 µg/mg 3 . In contrast, the PM2.5 levels due to stubble burning were around 28 µg/mg 3 on average.

The PM2.5 levels are also high during the winter because of the temperature inversion phenomenon. The temperatures in winter are low, and the colder temperatures trap pollutants near the ground. The warmer air rises to the top and sits atop the cold air to trap the pollutants and allergens, causing smog and reducing visibility.

Another significant cause of PM2.5 pollution in winter is the burning of crackers during Diwali, marriage celebrations, and other victory processions taken out by political entities. The cold winter air does not allow these impurities to escape into the atmosphere, forcing people to inhale them. As a result, studies show that the average life expectancy of humans in Delhi has shortened by nearly ten years.

• PM10 Pollution

Many people confuse PM2.5 and PM10 and consider them to be the same. But it is not so. PM2.5 pollution originates from combustion-based activities. For example, almost 95% of vehicular emission comprises PM2.5. On the other hand, PM10 pollutants are comparatively larger and arise from mechanical processes. The primary source of PM10 pollutants is road dust, construction site pollutants, and seasonal dust storms.

Source – https://www.iqair.com/in-en/india/delhi  

PM2.5 constitutes all aerosols under 2.5 µm, whereas PM10 comprises pollutants under 10 µm. So, PM2.5 is a subset of PM10. Therefore, PM10 samples show higher pollution density. PM10 was the only size fraction measure in India for a long time until PM2.5 was added to the list in 2009.

PM2.5 vs. PM10

PM10 comprises bigger particles that can irritate your throat, nose, and eyes. It is also inhalable and can deposit on the inner sides of the windpipe. On the other hand, PM2.5 is more dangerous because it can penetrate the deep parts of your lungs and even find its way into your blood.

Is there any safe level for PM2.5 and PM10?

The World Health Organization (WHO) has stipulated safe limits for PM2.5 and PM10 at 5 µg/mg 3 and 15 µg/mg 3 . However, the Central Pollution Control Board (CPCB) average permissible limits are 40 µg/mg 3 and 60 µg/mg 3 , respectively. Compare Delhi’s average PM2.5 and PM10 levels, and you will realize how dangerous it is.

Source – https://www.statista.com/statistics/1284233/average-monthly-pm25-in-cities-in-india/

This graph shows Delhi is the most polluted city compared to other prominent Indian metros. First, the PM2.5 level is consistently higher than the WHO and CPCB stipulations. Secondly, you can notice that the pollution level peaks during the winter months, thus, proving the temperature inversion theory right.

Source – https://aqicn.org/city/delhi/

The darker the squares, the higher the pollution levels. So, these real-time images prove that the air quality in Delhi has been consistently bad in 2022, with the winter months being the most dangerous. The monsoon months from July to October have been less risky.

• Chemical Pollution

We have discussed particulate matter pollution in Delhi by analyzing PM2.5 and PM10 pollution levels. However, besides PM2.5 and PM10, chemical pollution is a significant cause of pollution in Delhi. Chemical pollution constitutes toxic gases like Ozone (O 3 ), Nitrogen Dioxide (NO 2 ), Sulphur Dioxide (SO 2 ), and Carbon Monoxide (CO).

Research shows particulate matter pollution peaking during winter. So does that make the summer months less susceptible to pollution? No, because surface ozone pollution is at its highest in summer.

2022 has witnessed an unprecedented summer, with temperatures much higher than usual. The increased use of air conditioners and refrigerators has resulted in higher VOC emissions, a primary constituent of surface ozone. Besides, vehicular emission is a significant contributor to VOCs. Other VOCs and nitrogen dioxide sources include power plants, factories, and natural sources like plants.

Records show that the surface ozone level was consistently above safe limits for 85 days from March to May 2022. Mumbai was second with 75 days, and Hyderabad and Kolkata’s surface ozone levels exceeded the safe limit for 43 days each during the same period. South Delhi was the most affected region, followed by JLN Stadium, RK Puram, and Nehru Nagar. Noida, considered part of Delhi, was the most significant hotspot on the outskirts of the national capital.

Though the chemical pollution levels in Delhi in 2022 have been critical, they are nowhere as dangerous as particulate matter pollution. But together, they combine into a deadly combination that has endangered people’s lives in Delhi.

• Bhalswa Landfills

Source – https://www.livemint.com/news/india/delhi-bhalswa-fire-releases-toxic-chemicals-locals-demand-landfill-removal-11654311866396.html

Bhalswa Landfill is a dumping ground for different kinds of waste generated in Delhi. This landfill has been in use since 1984. This landfill, spread over 52 acres, has debris over 62 meters high. While it has grown beyond capacity, the Delhi Administration has done little to manage the waste. As a result, the trash starts decomposing, and the area is prone to fires.

The smoke generated from burning toxic waste material has unacceptable levels of carbon monoxide, hydrogen sulfide, and other poisonous gases. Moreover, it affects people living in its vicinity and the surrounding areas because the wind carries these gases almost all over Delhi.

• Stagnant Winds

Delhi has another climatic issue of stagnant winds. Sometimes, there is no wind movement at all. It forces the pollutants to concentrate in specific areas and pollute the air. On the other hand, a moving wind would have dispersed the contaminants away from the city.

• Geographic Location

Delhi’s unique geographic location is one of the principal reasons for its pollution problems. Delhi lies landlocked between Punjab, Haryana, Uttar Pradesh, and Rajasthan. Besides, the Himalayas in the north traps the winds and does not allow the pollutants to escape.

In contrast, cities like Mumbai and Chennai have vast open coastal areas that enable pollutants to escape over the sea. Delhi has a significant disadvantage in this regard.

• Population Explosion

The massive population growth has also contributed to polluting Delhi’s air. Census figures show that Delhi’s population increased from 16.7 million in 2011 to more than 20 million in 2019. As a result, Delhi has more vehicles, industrial products, and amenities that contribute significantly to air pollution.

• Inadequate public transportation

While Delhi has an impressive bus fleet, it is insufficient to cater to its growing population. As a result, the Delhi roads have more private vehicles, contributing to air pollution. A better and cheaper public transport system can solve matters.

We shall discuss the effects of air pollution in Delhi in the following section.

• How air pollution affects Delhi residents?

As discussed, PM2.5 pollutants are minute enough to penetrate the respiratory system and lodge themselves deep inside the lungs to cause respiratory damage. In addition, these particles can irritate and corrode the inner sides of the alveolar wall and affect lung functioning. So if you have a history of asthmatic problems, it can exacerbate the problem and end up as a severe respiratory ailment, leading to death.

Studies have shown that aerosols with diameters smaller than 10 µm can have an adverse impact on human health. The PM2.5 particles have large surface areas and, thus, pass through the filtration layers of nose hair and reach the end of the respiratory tract with the airflow and affect the air exchange mechanism in the lungs.

According to research, smoking one cigarette daily is equivalent to 22 µg/m 3 of PM2.5. So the Delhi air, with an average of 350 µg/m 3 of PM2.5 pollutants, is comparable to smoking at least 15 cigarettes daily. Therefore, you are reducing your life span by two and a half hours without touching a cigarette. On average, it adds up to nearly seven years in an average person’s lifespan of 70 years.  

Besides respiratory problems, inhaling PM2.5 pollutants can cause ailments like cancer and other cardiopulmonary problems. So pollution increases your medical expenses considerably. Therefore, environmental pollution can affect people’s mental and physical health.

Even short-term exposure to air pollution can cause lasting damage. Secondly, people who are already ill are more susceptible to respiratory diseases caused by air pollution. Children and older adults constitute the most vulnerable demographic.

The immediate after-effects of air pollution are eye irritation, headaches, fatigue, and anxiety. People also experience irritations in their noses and throat. PM2.5 is more dangerous than PM10 because it can enter the blood. Other significant ailments include damage to reproductive organs, the nervous system, the liver, and the spleen.

• Diseases and Deaths – Delhi population

Air pollution can have adverse effects on human health. This infographic should put things into proper perspective.

COVID-19 has claimed a significant chunk of the population prematurely. In addition, Delhi air pollution is causing considerable dents to the Indian population by claiming an estimated 54,000 premature deaths in 2020. The corresponding figures for 2021 were approximately 57,000. With the pollution situation worsening in 2022, one can expect the casualties to rise further.

The initial effects are visible in the form of eye, nose, and throat irritation. The long-term after-effects of air pollution are respiratory diseases like asthma, pneumonia, bronchitis, a chronic obstructive pulmonary disorder, cardiac problems, lung cancer, and damage to the nervous system.

Generally, Delhi experiences air pollution throughout the year. However, the situation worsens at the start of the winter in October and continues till March. This period coincides with agriculture stubble burning, the marriage season, and Diwali.

One must admit that COVID has reduced our immunity levels considerably. Add air pollution to the mix, and you have a deadly combination. Studies indicate that children are growing with smaller lungs. Almost one in three children in Delhi has impaired lungs, leading to chances of pulmonary hemorrhage.

The healthy population also suffers from smog issues and a dip in air quality. Delhi has reported a surge in hospital patients with respiratory problems. The common complaints include chest and nasal congestion and coughing.      

Controversies involving Agriculture Stubble Burning

Many people attribute agricultural stubble burning as the prime reason for Delhi’s air pollution. Though it is not the most significant cause of air pollution, stubble burning does play an important role in polluting the environment. So let us see what stubble burning is and whether it can be avoided.

Agricultural stubble burning is a relatively recent practice, especially by farmers using mechanized harvesters. However, farmers in the states of Punjab, Haryana, Rajasthan, and Uttar Pradesh burn their wheat, rice, and sugarcane crop residue after every harvesting season before the start of the new agricultural season. The crop residue burning releases smoke that affects air quality.

The National Green Tribunal has banned burning crop residue (also known as parali) in these states. It is also an offense under Sec 188 of the Indian Penal Code and the Air and Pollution Control Act of 1981.

Despite the legislation, farmers continue to burn parali, with official reports stating that more than 500 million tonnes of crop residue are produced annually. While rice and wheat crops are the primary culprits, other crops include maize, millet, and sugarcane. Statistics show that Punjab burns more than 20 million tonnes of rice stubble annually.

Burning parali or crop residue brings health issues because the smoke pollutes the environment. The air in the winter months is heavy. Hence, the smoke does not rise above the atmosphere and circulates at low levels to pollute the air we breathe.

Studies show that burning crop residue releases toxic gases like CO 2 (149.24 million tonnes), CO (9 million tonnes), SO x (0.25 million tonnes), and carbon (0.07 million tonnes). Besides, agricultural stubble burning releases 1.28 million tonnes of particulate matter. In addition to causing air pollution in Delhi and neighboring areas, agricultural stubble burning is the prime cause of the melting of Himalayan glaciers.

Modern-day agriculturists believe that stubble burning helps replenish the soil. But it does nothing of that sort because the heat generated by the fires elevates the soil temperature by nearly 10 degrees Celsius to kill bacteria and fungi that play a critical role in increasing soil fertility.

As stubble burning damages the microorganisms present in the soil, it affects their organic quality. Moreover, it invites enemy pests to destroy crops. In addition, stubble burning reduces the solubility capacity of the soil’s upper layers.

Indiscriminate crop residue burning reduces soil nutrients. Studies show that burning one ton of stubble results in a loss of 25 Kg of potassium, 5.5 Kg of nitrogen, 2.3 Kg of phosphorus, and 1 Kg of sulfur. We have already discussed the health effects of inhaling polluted air.

The stubble burning issue has generated various debates on air pollution, with politicians blaming each other. However, the Delhi Government has been vociferous in its opposition to stubble burning by Punjab and Haryana farmers.

So is there a solution to the stubble-burning problem? Yes, there is. Let us discuss the solutions to this issue that can go on to reduce air pollution in Delhi.

• Stubble-burning Solutions

Should stubble be burnt to get rid of it? Surprisingly, the answer is NO. Stubble burning is a recent activity, especially after the introduction of mechanical harvesters. Farmers used stubble as cattle feed and compost manure in the olden days. It also has use for building house roofs in rural areas. Today, stubble has various benefits like generating biomass energy, manufacturing packing materials, paper, bioethanol, and other uses like industrial production and mushroom cultivation.

The Union Government has formulated a National Policy for the Management of Crop Residue to help enhance soil fertility and save up to Rs 2000 per hectare from manure costs.

Various agricultural machines are available to manage crop residues. Though these machines are expensive, the Union and the respective State Governments are providing subsidies for investing in crop residue management machinery.

These machines include

• Baler – collect straw and make bales of paddy stubble
• Reaper Binder – harvest paddy stubble and prepare bundles
• Paddy Straw Chopper – cut paddy stubble and help integrate it with the soil
• Happy Seeder – help sow seeds in standing stubble
• Zero Till – prepare land for direct seed sowing in existing stubble
• Rotavator – prepare the land and incorporate stubble in the soil   

These machines can help the farmer use stubble in various ways and not require them to take the easy way out by burning it. We have seen that burning stubble does not help the soil. Secondly, it causes multiple health problems.

Besides, medical costs can be substantial. For example, studies conducted by the (ISEC) Institute for Social and Economic Change estimate that the Punjab rural folk spend Rs 7.60 crores annually for treating stubble-burning-related ailments. 

Stubble-burning usually coincides with the change of the kharif to the rabi season. By this time, winter had advanced in the northern parts of India. The dip in the temperature levels causes temperature inversion to take place and results in enhanced air pollution. Indians celebrate Diwali during this period. The bursting of crackers affects the environment considerably and exacerbates air pollution. Let us discuss the after-effects of the Diwali celebration on air pollution in Delhi.

• Issues Connected With Diwali

The primary causes of Delhi’s air pollution are vehicular emissions, industrial pollution, and agricultural stubble burning. However, Diwali celebrations also play a crucial role in worsening air quality in Delhi. Diwali usually coincides with the onset of winter and the burning of crop residue in the northern states. So, the pollutants emitted by bursting crackers linger in the atmosphere and exacerbate the problem to unmanageable levels.

The photograph above should explain it all. It was taken the morning after Diwali in Gurugram (near Delhi). See how polluted the environment is. Yes. We agree that Diwali is the most celebrated Indian festival. But can anyone deny that bursting crackers indiscriminately on Diwali adds to air pollution?

The following graph compares Delhi’s PM levels during Diwali for the last three years. Scrutiny shows that 2022 has been the best because of the least emissions. It may be due to greater awareness of the dangers that air pollution can have on human lives.

Bursting firecrackers during Diwali is enjoyable, and almost every Indian does it. But do you know the harmful chemicals that go into manufacturing these fireworks? Besides PM10 particles, bursting crackers release obnoxious gases like SO 2 , NO 2 , and O 3 . Other toxic chemicals used in manufacturing include iron, lead, manganese, copper, nickel, and beryllium.

The CPCB has listed nearly 15 substances in fireworks and classified them as toxic. So, is banning the manufacture and bursting of crackers during Diwali the ideal solution to curb air pollution? Secondly, people travel often during Diwali to purchase new clothes and gifts for family and friends. Thus, they add to vehicular emissions and worsen the AQI further.

Many people advocate a ban on the use of crackers. Some states, like Delhi, have also enforced bans on bursting crackers, whereas others have assigned specific periods for the purpose. Though all Indians celebrate Diwali, it is usually considered a Hindu festival. Therefore, a blanket ban on crackers would not be acceptable to all.  

Nevertheless, pollution control is a state subject, and the respective state governments must take stringent steps to ensure their residents get clean and pure air to breathe. Let us see how the Delhi administration has tackled this contentious issue of air pollution in the capital.

• How has the Delhi Administration tackled the problem?

Air pollution is nothing new for Delhi. The problems have been for more than three decades. The Delhi Administration has been fighting this contentious issue in various ways. Let us look at Delhi’s air pollution statistics since 2019 to understand the critical nature of the problem facing Delhi residents.

Statistics show that 2022 has been the worst year, with more days under the very poor and severe air quality categories.

Let us look at Delhi’s history or air pollution timeline to understand the situation better.

• The 1980s – The 80s saw a boom in vehicle sales in Delhi, leading to higher vehicle emission levels.
• 1996 – The Supreme Court of India took cognizance of Delhi’s air pollution and instructed the government to formulate an action plan.
• 2000 – A spurt in construction activities resulted in increased PM10 and PM2.5 pollutants. Besides, vehicles increased in Delhi at an annual growth rate of 10.75%.
• 2004 – The National Air Quality Index concept was introduced in 2004. It categorized air quality into six levels, a) good, b) satisfactory, c) moderate, d) poor, e) very poor, and f) severe or hazardous.
• 2016 – The Diwali season in 2016 was the worst experienced by the capital in history, with the AQI levels crossing 750 µg/m 3 . The entire city was under smog.
• 2017 – If the 2016 smog was terrible, the 2017 Great Smog was horrible, with PM10 levels touching 999 µg/m 3 . A cricket match was stopped due to pollution for the first time in history, with many players vomiting and showing signs of distress.
• 2019 – The Delhi government declared a public health emergency and closed schools and educational institutions in November.
• 2022 – The situation has worsened over the years.

Let us see the Delhi Administration’s history of responses to tackle air pollution.

The timeline shows that Delhi’s air pollution problems originated more than four decades ago, in the 1980s. However, the Supreme Court of India started hearing a PIL filed by noted environmentalist and lawyer M C Mehta in 1995. It indicated that vehicular and industrial emissions were the principal causes of air pollution.

So the Supreme Court ordered the closure of Delhi’s most polluting industries in a phased manner. It also ordered the relocation of brick kilns outside the city’s limits. The Delhi government submitted an action plan in response to the court’s order. It resulted in formulating the Environmental Pollution Control Authority of Delhi in 1998.

The Supreme Court acted on EPCA’s recommendations and ordered the conversion of Delhi’s public transport vehicles to CNG. It also ordered the phasing out of all pre-1990 autorickshaws. Other corrective measures included the removal of leaded petrol, phasing out 15 and 17-year commercial vehicles, and limiting the number of 2-stroke autorickshaws to 55000. In addition, coal-based power plants were converted to gas-based units.

The Delhi Government revised the National Ambient Air Quality Standards (NAAQS) in 2009 to add 12 more pollutants, including PM2.5. While WHO prescribed acceptable levels of 5 µg/m 3 for PM2.5 and 15 µg/m 3 for PM10 contaminants, the NAAQS stipulated 40 µg/m 3 and 60 µg/m 3 for PM2.5 and PM10, respectively.

A US-based Health Effects Institute published a report stating that Delhi was the most polluted city in the world between 2010 and 2019, with an average annual exposure of 110 µg/m 3 PM2.5.

2016 saw the Delhi government try out an innovative scheme of odd-even vehicle rationing in January and April. That winter saw Delhi experiencing the worst smog in history, with PM2.5 and PM10 levels reaching an unprecedented high of 999 µg/m 3 .

The Ministry of Environment and Forests (presently the Ministry of Environment, Forests, and Climate Change MEFCC) introduced a Graded Response Action Plan in 2017, involving close coordination between various agencies to tackle Delhi’s air pollution issues.

Studies conducted by IIT Delhi, IIT Madras, and Delhi Pollution Control Committee showed that vehicular emissions, rapid industrialization, the spread of urban areas, and the increasing population were responsible for the high pollution levels. The population grew from 13.78 million in 2001 to 16.78 million in 2011 and further to more than 20 million in 2019. As a result, vehicles increased to 10.9 million by March 2018.

Besides, the CPCB found that most of Delhi’s small and medium industries in the polluting clusters do not meet stipulated standards for air, water, and soil pollution. The number of such industries was more than 3100 spread over the NCR. As a result, PM2.5 pollutants were the single most contributor to Delhi’s air pollution. The following statistical presentation explains it the best.

However, did the remedial measures initiated by the Delhi government yield the desired results?

• The conversion from petrol and diesel to CNG was not entirely successful because it reduced SPM and PM10 levels but increased carbon monoxide levels.
• The cap of 55000 autorickshaws was not revised until 2011. In the meantime, four-stroke engines and CNG were introduced. But the autorickshaw sector could not grow, leading to the black marketing of auto permits.
• While the Delhi human population grew by 45% between 1997 and 2011, the vehicular population grew by 250%. Besides, Delhi’s public transport is inadequate. Compared to Delhi, Paris has an extensive metro system, even though Paris is smaller than Delhi.
• The odd-even vehicle number rule flopped miserably because the principal culprits, the heavyweight vehicles, were exempted from this ruling.
• Delhi has an inadequately equipped waste management system. While the daily waste generation is over 10000 tons, the landfills can hold not more than 6000 tons. As a result, it leads to the burning of waste and exacerbates the pollution problem.
• Studies show that a significant proportion of polluting sources are present throughout the year. But the situation worsens in winter because of low temperatures.
• Farm stubble burning is a seasonal issue. While the principal contributors are farmers from neighboring states, it has become more of a political challenge than a problem concerning Delhi residents.
• The Political Slugfest – Does it do any good?

The Delhi Government has always played the blame game when dealing with farm stubble burning. The present AAP-led government did not leave any stone unturned in blaming the neighboring states, like Punjab, Haryana, Uttar Pradesh, and Rajasthan.

The AAP government led by Arvind Kejriwal has always been renowned for its theatrics and blame-shifting capabilities. For example, it blamed agricultural stubble burning as the most significant issue causing air pollution in Delhi. However, the blame lies elsewhere, as discussed in this article.

Source – https://indianexpress.com/article/india/punjab-delhi-haryana-up-action-plan-stubble-burning-air-pollution-7528596/

The blame game continued as long as the neighboring states were governed by parties other than the AAP. However, Punjab has an AAP government today. Moreover, recent interviews and press conferences by Arvind Kejriwal concerning farm stubble show the AAP Delhi government taking a soft stance towards Punjab while blaming the other states.

Today, the Delhi government talks of remedial measures and suggests alternative uses of crop residue as its invention. But these measures have already been suggested in the past. However, only some farmers have adopted them. Therefore, the results are not visible. The need of the times is for all farmers to adopt these solutions and stop farm stubble burning completely. The political slugfest is not doing any good to anyone.

Nevertheless, farm stubble burning is not the only issue. As a result, the government can take more steps to bring Delhi’s air pollution levels under control.

How can the problem be resolved? – Steps Government should take

Air pollution does not know or recognize state boundaries. Hence, governments should exhibit a strong political will and employ the best technologies to tackle the problem. The Delhi government has initiated several measures, but more needs to be done.

• Outdoor Air Purifiers

If you have traveled across the length and breadth of Delhi, you must have noticed huge refrigerator-sized machines placed at some of the busiest traffic intersections. These outdoor air purifiers suck in the pollutants emitted by vehicles and pump fresh air.

The CPCB has cleared the installation of 54 such machines across Delhi. Each machine costs nearly Rs 2.60 crores.

These air-purifying machines comprise three filters to trap particulate matter and dust. They also contain UV lamps that trigger photocatalyst-coated charcoal particles to oxidize and transform the VOCs that pass through the filters into carbon dioxide and water. The machines working currently can purify air over a 500 square meter area. Larger and more powerful devices capable of purifying areas up to 10000 square meters are in the pipeline.

However, are these machines useful? That is a million-dollar question because each machine costs around $370,000. Furthermore, can these machines be efficient in an outdoor environment? The Center for Science and Environment has expressed its doubts over the machine’s efficacy. They contend that the devices can work efficiently in a lab-controlled environment but not outdoors. The impact area is approximately 2 to 3 square meters around the machine.

Even assuming the machines are efficient, the pollutants they remove are minuscule compared to the haze enveloping Delhi. The World Health Organization has rated Delhi the most polluted of the large cities worldwide. The problem can only worsen, especially as the UN predicts Delhi to become the world’s largest city by 2028.

• Portable Air Filters and other innovative technologies

The CPCB has tried an innovative technique to curb air pollution by installing small air filters atop public buses. Around 30 buses come with these filters that can trap pollutants while on the move and provide some respite. But, it is like a drop in the ocean. More work is necessary in this regard.

The CPCB plans to treat construction-related pollution by sprinkling magnesium chloride and cement on roads and construction installations. They believe that these hygroscopic materials absorb moisture from the air and make the ground wet to prevent dust from flying in the air. Similarly, the agency announced a cloud seeding project to create artificial rain and wash away pollution.

One can classify these attempts as Band-Aid solutions. How can they be effective when there is enormous scale pollution? Delhi should look at other cities like Mexico City, Los Angeles, Cairo, and Beijing and study how they faced the challenges of air population. One has to concede that Delhi has a massive population. Therefore, the solutions are never going to be easy. However, they require a strong political will and not publicity stunts that the government is presently engaging in.

Here are some steps the government can take to reduce air pollution.

• Stop stubble burning – Stubble burning is an external problem, but it affects Delhi air more than anything else. So, the respective governments to sit together and formulate alternate measures rather than blaming each other.
• Proper waste management – The Delhi government must improve its waste management technology and not rely on burning waste. One solution is to shift the landfill areas outside the city limits and set up waste management plants to convert waste into farm manure. Waste can also be converted to energy and alternate biofuel for vehicles.
• Encourage clean fuel like CNG or electric vehicles – CNG is a purer option than standard fuel like petrol and diesel. The Delhi government has already mandated public transport vehicles to use CNG. The thrust should now be on private and commercial transport vehicles. Electric cars are also an excellent option. But there is a lot to do on the infrastructure front. Besides, BSVI norms should become mandatory for all vehicles, and all existing vehicles with BSIV engines should be phased out gradually.
• Promote environmentally friendly products – Almost every home has refrigerators and air conditioners. Unfortunately, these appliances emit volatile organic compounds that can pollute the environment. So, the government should encourage people to use environmentally-friendly products and help the government in controlling air pollution.
• The 15-point Winter Action Plan formulated by the Delhi Government.

The Delhi Government has formulated a 15-point Winter Action Plan to control air pollution. However, it requires active cooperation from the public.

• Bio-decomposer for farm stubble – The PUSA Institute has developed a liquid bio-decomposer that can deal with farm stubble without burning them. This year, the government has distributed this bio-decomposer free to farmers to decompose farm residue and cover around 4000 acres. It has plans to provide such machines to more farmers and cover up to 5000 acres in the following action plan.
• Garbage burning and cracker ban – Garbage disposal by burning them is a crucial pollution source. So, the government has banned its burning and formed 611 crack teams to identify instances of garbage burning. Similarly, 210 units are working to catch offenders bursting firecrackers, contributing to air pollution. This ban will continue till January 2023.
• Monitoring construction sites – The government has mandated that anyone constructing buildings with an area of more than 5000 square feet should register on the web portal and use anti-smog guns to monitor dust control on a real-time basis. Nearly 586 teams are monitoring these activities.
• Use of anti-smog guns – The Delhi government has plans to install 233 anti-smog guns and 150 mobile anti-smog guns across the city to combat pollution.
• Use of sweeping machines – The Delhi government has employed nearly 80 road sweeping machines. Besides, 521 water-sprinkling machines are put in force to sprinkle water and prevent dust from flying into the air.
• Route Diversions – The government has identified 203 busy traffic routes and is preparing alternate routes to prevent traffic congestion and reduce vehicular emissions.
• Green Room and scientific monitoring – The government has partnered with IIT Kanpur to set up a green room to monitor pollution control measures. This facility has nine scientific experts monitoring air quality across Delhi in real time.
• Process e-waste – A 20-acre e-waste park is being set up to process electronic waste in the city.
• Hotspot supervision – The government has identified 13 hotspots where it will strictly supervise air pollution control measures.
• Paryavaran Mitras – Nearly 3500 volunteers have enrolled as Paryavaran Mitras to create awareness of air pollution and help the government tackle the issue. Anyone can become a Paryavaran Mitra by dialing a missed call to 8448441758.
• Enhance Green Cover – Planting trees is the best way to increase green cover over Delhi. Unfortunately, rampant deforestation and cutting down trees to facilitate infrastructure development have taken a heavy toll. So, the government plans to reverse the process by aiming to plant 42 lakh trees across the capital.
• Green Delhi App – The government has launched a new mobile app, Green Delhi App, where residents can raise complaints regarding pollution. The government states that nearly 53000 complaints have been lodged, with a high resolution rate of 90%.
• PUC Certificates for vehicles – Petrol vehicles older than 15 years and diesel automobiles over 10 years old are mandated to hold PUC certificates. The government has formed 380 teams to ensure strict enforcement.
• GRAP (Graded Response Action Plan) – The government plans to upgrade this plan already floated by them last year. This plan envisages forecasting deterioration of air quality at least three days in advance.
• Cooperate with neighboring NCR cities – Active cooperation is necessary between the Delhi government and the neighboring states to ensure the successful implementation of the 15-point Action Plan. It concerns providing 24×7 electricity to all neighboring cities like Gurugram (industrial hub) to eliminate the use of diesel generators.     

While the government is doing its best to control air pollution, residents also have a crucial role to play. So let us now discuss the steps people can take to reduce air pollution and get relief.

• The Present Situation – Steps people can take to get relief

The government does what it has to do to resolve air pollution issues. But people should play their role in supplementing the Delhi Administration’s efforts. Let us discuss some steps that people should take to get relief from air pollution issues.

• Use Air Purifiers – Air purifiers are the best appliances in indoor areas like homes, offices, restaurants, cinema halls, etc. These appliances are available at reasonable prices. So, a family can have one air purifier for every room, especially when children and older adults are present in their homes. These appliances provide pure air and protect you from the effects of inhaling polluted air.
• Reduce unnecessary travel – The best way to protect oneself from air pollution is to avoid going out of the house unnecessarily. Reducing unnecessary travel can result in fewer vehicular emissions to benefit society. Single individuals need not go around in their cars. Using public transport is a better idea.
• Use environmentally friendly appliances – People should use ecologically friendly appliances at home that reduce ozone pollution. For example, while air conditioners and refrigerators are essential during summer, keeping your home’s windows open and allowing fresh air circulation is better.
• Wear masks whenever you go out – COVID-19 has already forced people to wear face masks whenever they step out of the house. So, continuing this practice to prevent inhaling polluted air should not be a problem. It is advisable to use N95 and N99 masks because they can prevent PM2.5 particles from entering your respiratory system. However, it should be worn snugly and cover the entire nose and mouth.
• Avoid strenuous exercises – While walking and jogging are excellent exercises to keep you healthy, they do not serve any purpose if you inhale the polluted air. Therefore, it is better to avoid strenuous activities. Besides, people tend to feel breathless when exercising, forcing them to breathe through their mouths. That can be dangerous because it allows more significant contaminants to enter the system easily.
• Plant air-purifying plants indoors – Plants like Ivy, Spider Plants, and Aloe Vera have air-purifying properties. So, having these plants in homes and offices can purify the indoor air. The best feature is that these are low-maintenance plants because they do not require frequent watering or adequate oxygen.
• Take frequent steam baths – Steam baths can help open the skin pores and allow them to breathe easily. It helps relax airways and helps the body eliminate hazardous substances through sweat and mucus. You can add a couple of drops of eucalyptus oil to a jug of boiling water and inhale the steam. It helps open up the lungs and clears the nasal passage blocks.
• Consume healthy food – One should take care of their health to develop immunity levels that can help them fight diseases caused by inhaling polluted air. So, a healthy diet comprising Vitamin C-rich fruits, omega-rich foods, and magnesium-rich foods is essential. Vegetables like carrots, radishes, sweet potatoes, and spinach are excellent sources of Vitamin A. Oranges, sweet limes, and lemons are rich sources of Vitamin C, whereas bran oil and almonds contain Vitamin E.
• Monitor air quality Index – The Delhi government has launched its Green App. Besides, the AQI app is also available for free on PlayStore and AppStore. So every Delhi resident should have these apps on their smartphones to enable them to monitor air pollution levels in the city. So they can avoid heavy traffic congestion and places where the air quality is hazardous.
• Use environmentally free personal care products – Your perfumes can contain pollutants that can emit VOCs and harm the environment. So it is advisable to use good quality products that do not pollute the atmosphere and worsen the air quality.
• Ventilate your homes adequately – The air quality is not always unfavorable throughout the day. Your smartphone app alerts you in this regard. So you can ventilate your homes accordingly to let in as much fresh air as possible. Proper air circulation allows you to inhale healthy air.

We have discussed steps individuals can take to control air pollution. The government is also playing its part. But there is much to learn from the mistakes of others. For example, Delhi was not always top of the list of highly polluted cities. There was a time when Beijing used to top the list. However, the situation has improved, and is considered a much cleaner city today. So, Delhi can learn from Beijing and resolve some of its air pollution problems.

• Lessons Delhi can learn from China.

Beijing was once counted among the highly polluted cities in the world. The air quality was so bad that it caused a health crisis, killing nearly one million people annually. However, today, Beijing has dropped out of the world’s first 200 most polluted cities. Delhi can benefit from the Beijing experience and improve its air quality. Let us see what Beijing did to come out of the crisis.

The Chinese government shut down coal-fired power plants in the main cities to reduce pollution. Cities like Shanghai, Beijing, and Shenzhen restricted cars on the streets and introduced electric buses. In addition, the country shut down its coal mines and reduced its iron and steel-making capacities.

The government encouraged afforestation and planted over 35 billion trees across 12 provinces. In addition, they earmarked a massive budget for reforestation programs and followed them up vigorously to ensure adequate tree planting and increase the green cover.

China released its Air Pollution Action Plan in 2013 to reduce its PM2.5 levels by 33% in Beijing. It also took up river-cleaning attempts to succeed in its endeavor. Delhi can follow suit by cleaning up the Yamuna and preventing industrial and human waste disposal.

On achieving the Air Pollution Action Plan, China introduced its Three-Year Plan for Winning the Blue Sky War in 2018. It mandated a minimum of 18% reduction in PM2.5 levels to bring it to par with international standards.

The first action plan did not address the problem of surface-level ozone. However, we have seen that surface-level ozone is a critical cause of air pollution in Delhi, which is responsible for the higher number of asthma and chronic obstructive pulmonary disorder cases. Therefore, the new action plan focused on eliminating surface-level ozone and reducing VOC and nitrogen oxide levels to meet international standards.

COVID-19 helped China achieve its objectives by implementing strict lockdowns and clamping down on offenders. As a result, the decrease in industrial activities helped considerably reduce greenhouse gas emissions and improve air quality.

As a result of the strict measures taken by China to address its air pollution problems, the life expectancy of the average Chinese resident has increased by 2.4 years.

Delhi can learn lessons from China and other countries that have combated air pollution. Though it will take time for the Delhi air quality to reach ISO standards, it must start soon. So let us now understand what the ISO standards on air quality are.

• ISO Standards on Air Quality

We have discussed much about Delhi’s poor air quality and the harm it causes to life and the environment. But do you know that 91% of the world’s population lives in places that do not meet international standards or WHO limits? So, what are the international standards? Let us discuss them here.

The World Health Organization stipulated the following Air Quality Guideline levels in 2005 and improved them in 2021.

Source – https://www.who.int/news-room/feature-stories/detail/what-are-the-who-air-quality-guidelines

• AQI Standards

While it is presently impossible for Indian cities to achieve WHO standards, we can at least try to come close to AQI standards. AQI has stipulated the following standards to decide the air quality.

Source – AQI

• Delhi vs Other Indian cities

We have discussed Delhi’s air pollution in detail. But do you know how other Indian cities fare compared to Delhi? Let us compare the real-time figures of India’s top ten polluted cities on December 03, 2022.

AQI is India’s most reliable source for data concerning air pollution and air quality index. Here are the top ten highly polluted cities in India presently.

• Patna – 219
• New Delhi – 212
• Sonepat – 204
• Nagpur – 200
• Hissar – 196
• Rajgir – 194
• Faridabad – 191

Similarly, let us also look at the ten least polluted cities in India today.

• Aizawl – 12
• Kilkunda – 17
• Rameswaram – 19
• Tuticorin – 24
• Coimbatore – 24
• Kodaikanal – 25
• Channarayapatna – 25
• Manali – 29
• Major Air Pollutants in Delhi – Real-time data – December 03, 2022
• PM2.5 – 161

Currently, the PM2.5 concentration in Delhi is 10.7 times above the WHO recommended limits.

• Frequently Asked Questions – Delhi Air Pollution

The AQI provides real-time information on every aspect of air quality in any city in India. In addition, you can download the mobile app on your smartphone and get information on the go.

Yes, the AQI in Delhi is alarming. It is consistently higher than the WHO stipulated standards. So, it is classified as ‘Very Unhealthy’ to ‘Severe’ almost throughout the day.

Winter is the worst season in Delhi in terms of air quality. The low temperatures and fog are accentuated by vehicular and industrial emissions and smoke from agricultural stubble burning in the neighboring states. It causes a haze over the city that does not vanish even when the sun shines brightly over the sky.

Yes. Rainfall does not allow the dust particles to fly around in the air and cause discomfort. Instead, they settle down on the ground and get washed away.

Usually, the evenings are severe because of traffic jams causing massive vehicular emissions that pollute the air to the maximum levels.

The mornings are comparatively better. But the smog and haze are omnipresent throughout the season because of heightened air pollution.

Yes. It is advisable to wear a mask, especially when you go out. An N95 or N99 mask is advisable as it prevents PM10 and PM2.5 pollutants.

Air purifiers are the best appliances that improve air quality indoors. So, it is recommended to use these machines to get relief from air pollution.

The Delhi government is taking various steps to address the issue. However, it requires the citizen’s support. Though it will take time, the air pollution scare can end.

Yes, inhaling polluted air invites a lot of diseases and ailments that can shorten life expectancy by ten years on average.

Delhi is a virtual gas chamber today because of the city’s hazardous air pollution levels. It is almost impossible for Delhi residents and visitors to get around with their regular work without inhaling unhealthy contaminants.

Virtually every individual in Delhi has some physical ailment. Children and elderly people are the most vulnerable. So, it requires a lot of firefighting for the government to clean up Delhi’s air.

Residents must also pitch in with their concerted efforts in their own interests. However, nothing is impossible because cities with worse track records than Delhi have solved their air pollution problems. In this research article, we have discussed all aspects of Delhi air pollution, its causes and effects, and the possible solutions to the problem.  

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Pollution In Delhi Essay, Speech, Article, Paragraph, Composition

• 4 minute read

• May 27, 2021

The air quality in Delhi has been a matter of grave concern for a rather long time now. Delhi is often called the ‘gas chamber’ and the ‘world’s most polluted city’. -Pollution in Delhi has been a matter of grave concern for a rather long time now. -Delhi is often called the Gas Chamber. -Delhi is the most polluted city in the world. -The air quality in Delhi has been a matter of grave concern for a rather long time now. -Delhi is often called the Gas Chamber. -Delhi is the most polluted city in the world. -The air quality in Delhi has been a matter of grave concern for a rather long time now. -Del

Pollution in Delhi is one of the worst in the world at the moment. According to WHO, Indian capital has been ranked as the world’s worst pollution hotspot. The air quality of the national capital has been worsening over the years and according to recent report, Delhi’s air quality is 6 times more polluted than what is considered safe for human beings.

In India, Delhi is considered to be one of the most polluted cities in the world due to high levels of particulate matter and other kinds of pollutants in the air. It’s a place that is so polluted that its air can be considered to be toxic. The cause of these high levels of pollution is mainly due to the growing population of Delhi. In just the last few years, the number of people living in the city has increased by nearly 25% making it extremely difficult to control the amount of pollution that comes from factories, cars, and other types of transportation. This pollution leads to health problems such as asthma and bronchitis.

Pollution in Delhi Essay, speech, article, paragraph, essay

People of Delhi, do you breathe oxygen or poison?

Pollution in Delhi

Control measures to reduce pollution in delhi, odd even formula.

Under the program, which started in January, cars with even and odd numbers will run on different days. This reduces both pollution and inconvenience caused by bulky vehicles.

We take care of our defenders

The government has handed out masks to traffic cops. It will protect them in the middle of a pollution cloud.

Why should the rich be spared?

The Supreme Court has banned cars over 2,000cc. This also applies to off-road vehicles. The taxi owners turn around: The Supreme Court has ordered that all taxis in the capital must switch to CNG by March 2017. The National Green Tribunal has issued a call to public portals and administrations to abandon all diesel vehicles. We all know diesel is cheaper, but are we willing to pay high hospital bills? The government will do its part, but that doesn’t take away our part. Actions to be taken by all citizens to reduce pollution include

Residents of Delhi must take measures to curb pollution

No privacy, but public.

City dwellers should make more and more use of public transport to reduce pollution in cities. The government has ensured that the number of buses and auto rickshaws in the capital will be increased.

Don’t be greedy

Citizens should start using CNG in their vehicles. It may cost more than diesel, but if there is health, we are there.

For a while you have to hide that beautiful face

The use of face masks such as the N99 and N95 largely prevents people from inhaling toxic substances.

More dull eyes

Citizens should avoid contact with construction sites. These places emit gases that make the air very harmful to the eyes and respiratory system. Many of us know the above measurements, but the level of the nation’s capital remains the 11th most polluted city according to WHO rankings. I call upon every citizen to take action to make the capital and India pollution free.There are many many environmental issues on our planet. The most well known of them is global warming. If you’ve done any research at all, you know that the number one contributor to global warming is carbon dioxide. But where does all this carbon dioxide come from? The answer is us. It comes from our cars, our factories, and even our washing machines.. Read more about  air pollution in delhi essay in english 250 words  and let us know what you think. Don’t hesitate to find academic experts at SmartWritingService, a  pro essay writing service , if you need help writing an essay, speech or any other paper on pollution topics.

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