Toxic Air, Chronic Diseases: Pollution Measurement Varies, But Not Ground Reality

Air pollution is the biggest environmental threat causing serious health issues and consequential deaths in India. According to the World Health Organization (WHO), seven million premature deaths take place every year globally due to the combined effects of outdoor and household air pollution. 

According to the 2024 State of the Global Air, air pollution-related deaths stood at 8.1 million in 2021.

Decoding Air Pollution 

Air pollution is a complex mixture of solid particles, liquid droplets, as well as gases. It can come from multiple sources – household fuel burning, industrial chimneys, traffic exhausts, power generation, open burning of waste, agricultural practices, and desert dust, among others.

Key air pollutants include PM2.5 and PM10 (particles with an aerodynamic diameter of equal to or less than 2.5, also called fine, and 10 micrometres, respectively), ozone (O3), nitrogen dioxide (NO2), carbon monoxide (CO), and sulphur dioxide (SO2).

Health Impact

Air pollution has substantive health impacts. Fine particulate matter (PM2.5) penetrates through the lungs and further enters the body through the bloodstream, affecting all major organs. Exposure to PM2.5 causes diseases both to our cardiovascular and respiratory systems, leading to strokes, lung cancer, and chronic obstructive pulmonary disease (COPD).

A recent research has shown the association between prenatal exposure to elevated levels of air pollution and developmental delay at age three, as well as psychological and behavioural problems, including symptoms of attention deficit hyperactivity disorder (ADHD), anxiety, and depression.

Where does India stand?

Teetering On The Edge

Put mildly, India is teetering on the brink. The Global Burden of Disease Study 2010, published in Lancet way back in December 2012, estimated that 1.5 million Indians died annually (one-sixth of all Indian deaths), due to both outdoor and indoor air pollution.

Also, the WHO reported in 2015 that India accounted for the world's highest death rate from chronic respiratory diseases, and more deaths from asthma than any other nation. Air pollution also contributes to both chronic and acute heart disease, the leading cause of death in India.

The Silent Killer Kills Violently

According to a World Bank Report dated June 5, 2024, India’s entire population is exposed to unhealthy levels of PM2.5 – the most harmful pollutant – emanating from multiple sources. 

As per the Institute for Health Metrics and Evaluation (IHME)/Global Burden of Disease — 2021–2024 (latest data summaries), the number of annual deaths due to air pollution has spiked to 2.3 million.

Among The Worst

How does the air pollution in India compare to other countries? According to the World Air Quality Report 2023 by Swiss Agency IQAir, India had the third-worst air quality (next to Bangladesh and Pakistan) with an average annual PM2.5 concentration of 54.4 micrograms per cubic metre. It was no different in 2024, with India placed as the fifth most polluted nation – Chad, Bangladesh, Pakistan, and Congo being worse than New Delhi. 

India's average PM2.5 concentration in 2024 was 50.6 µg/m3, equivalent to an AQI of 138, classified as “unhealthy for sensitive groups". This level is 11 times higher than the WHO annual 5 µg/m3 guidelines.

An analysis of the IQAir data shows statistics of the number of Indian cities in the list of the 100 most polluted cities of the world:

• 2015 - 43
• 2020 - 62
• 2021 - 68
• 2022 - 70
• 2023 - 81

The statistics are disturbing. And this goes on to show that either the country is not doing enough to tame pollution, or the measures undertaken are ineffective. 

The Twain Do Not Meet

There is a significant difference between how India and the WHO measure air pollution. Over the decades, the WHO has tightened its air pollution guidelines that were first issued in 1987. It last revised its 2005 guidelines in 2021. Below is the comparison of the WHO 2005 and 2021 Air Quality Guidelines (AQG). 

Firstly, let us take a look at the WHO guidelines: the recommended 2021 AQG level compared with the 2005 guidelines: 

μg = microgram
a 99th percentile (i.e., 3–4 exceedance days per year).
b Average of daily maximum 8-hour mean O3 concentration in the six consecutive months with the highest six-month running-average O3 concentration.

The Indian Air Pollution Guidelines

The table below shows the Indian standard for the measurement of various pollutants. At first glance, it is apparent that the Indian standards are nowhere close to the mandated levels of the WHO. Evidently, the twain do not meet, and there is an urgent need to align the Indian pollution standards with the latest WHO guidelines. 

One Does Not Know What One Does Not Measure

A key issue with India is that it does not accurately measure air pollution. According to a July 2023 study by the Centre of Science and Environment (CSE), only 12% of the country’s 4,041 census towns have air quality monitoring systems. Worse, only 200 cities monitor all the six key criteria pollutants. Also, 47% of India's population lives outside the 50 km radius coverage of the country's combined manual and real-time air quality monitoring network.

India needs no less than 20,000-25,000 air quality monitoring stations. Sadly, even as per the government’s latest data, it has barely 1,524 stations (558 continuous and 966 manual). Most stations are located in bigger cities with a large part of the urban area and the total rural area outside the monitoring network.

And the problem does not end there.

The Dichotomy

The dichotomy persists in how India and the world measure air pollution. Indian pollution standards cap the maximum AQI level at 500, while international trackers such as IQAir monitor it irrespective of the level. Capping the AQI level at 500 is based on a bizarre logic.

Let’s understand the logic behind this cap. 

Whatever AQI value is beyond 500, the health hazard remains the same, as 500 AQI already signifies the worst.

Capping AQI  at 500  avoids a public health emergency.

The above being the case, it is impossible to know the authenticity and the seriousness of air pollution in the country. 

What is further worrisome is the fact that the air pollution monitoring mechanism in India has turned dysfunctional, as is evident from the analysis of the daily air pollution monitoring in various cities by the Central Pollution Control Board (CPPB). 

The 'Capital' Punishment

The country is increasingly getting engulfed by the rapidly worsening air pollution situation, which is affecting those living in the northern, central, and Indo-Gangetic plains the most. New Delhi has indisputably emerged as "the pollution capital" of not just the country but also the world. This does not augur well, considering India is now in the Big League as far as global economies go.

In 2024, as per IQAir, with an average PM2.5 concentration of 91.8 µg/m³ (WHO guideline limit is 5.0 µg/m³), New Delhi was adjudged the most polluted capital city of the world for the seventh year in a row.

Delhi's air quality has been worsening over the years, notwithstanding the government's efforts and continuous monitoring and intervention by the Supreme Court.

The Air Pollution Crisis 

Much before Diwali day, Delhi entered the grip of a “very poor” AQI level, and ever since, it has dangerously dangled between “very poor” and “severe” or hazardous. 

There are two key sources of knowing the Delhi Air Pollution - one is the AQI data set, and another is the government data.

Here goes the story of November 11:

Firstly, according to IQAir data on November 21, 2025, the Air Quality Index (AQI) for Delhi was in the hazardous range, with values crossing 450 at peak times. The AQI at 7 a.m. was reported at around 455, with major pollutants PM2.5 at approximately 280 µg/m³ and PM10 around 370 µg/m³. This level of pollution is equivalent to smoking 11 cigarettes a day and poses severe health risks to the population.

The cities neighbouring the NCR region were also in the grip of hazardous pollution, with the AQI index hovering at 570 in Faridabad, 417 in Gurugram, 514 in Noida, 458 in Greater Noida, and 543 in Ghaziabad, respectively.

Secondly, as per government data, at 4 p.m. on November 20, the average AQI shown on the CPPB website was 391, and the AQI level at 4 p.m. on November 21 was 362.

On the morning of November 20, the air quality in New Delhi jumped to the “severe” category, touching the 400 AQI mark. November 21 was just a tad better, with data from the CPCB-developed Sameer app showing AQI at 13, out of the 39 air monitoring stations, in the "severe" category, with Wazirpur being the worst affected at 442. AQI at other stations was technically in the "very poor category". 

Ineffective Approach

The Ministry of Earth Science Air Quality Early Warning System has dire predictions for the coming days – AQI is likely to hover dangerously between the "very poor" and "severe" range. Every year, as winter approaches and AQI hits the “poor” button, the multi-layered Graded Response Action Plan (GRAP) is set in motion in New Delhi and the NCR region.

Currently, over and above the restrictions imposed as part of GRAP-I and GRAP-II measures, severe restrictions have been put in place as part of GRAP-III, practically bringing the city to a standstill. 

Despite these measures, it is no secret that GRAP is not working, and the air quality continues to worsen by the day. This underlines the fact that the measures are inadequate and ineffective, making air pollution a serious public health emergency.

The Way Forward

Though New Delhi pollution continues to hog the limelight, the country is fast getting converted into a killer gas chamber. India launched its Air Quality Index (AQI) on September 17, 2014, offering a simple numerical scale to communicate air quality and its health impacts. This gave some ray of hope, but it did not change the ground reality.

The launch of the National Clean Air Programme (NCAP) in 2019 was a moment of renewed hope. It aimed to cut particulate pollution by 20–30% by 2024 (from 2017 levels), and it was later revised to a more ambitious 40% reduction by 2026. It is yet to make any impact, though.

Armed with GRAP, the Commission for Air Quality Management (CAQM) was set up to drive coordinated action in the NCR and other regions. GRAP has remained ineffective.

This clearly highlights one thing – India needs to change its approach towards combating air pollution. As air pollution does not respect municipal boundaries, tackling it demands integrated, regional strategies based on the idea of the “airsheds” approach – analogous to watersheds – that extend well beyond local emissions control. 

An effective, airshed-based strategy would require a significant shift in the country’s current approach. The issue is complex, but it is time for an urgent purposive action. India needs to urgently look into this issue. The country must begin by measuring its air pollution correctly and raising the pollution threshold closer to the WHO air quality guidelines.

(The writer is a former civil servant. Views are personal.)