Growing Body of Data Links India’s Polluted Air to Worsening Health
Pollution in Delhi peaks in late autumn when drifting emissions from crop burning exacerbate the usual urban household, traffic and industrial sources

A growing body of evidence from India is firmly establishing the country’s toxic levels of air pollution as a leading cause of ill health, particularly non-communicable diseases (NCDs).

The results are significant because the country’s politicians have repeatedly questioned the validity of research that links air pollution with reducing life expectancy and worsening health. 

As many as 80 out of the 100 most polluted cities in the world are in India, as Health Policy Watch reported earlier ithis year, making air pollution a huge health stressor. 

The latest research from India demonstrates how air pollution is worsening anaemia, hypertension, diabetes, cholesterol levels and mental health, as well as other diseases.

Around 74% of all deaths worldwide are attributed to NCDs, according to the World Health Organization (WHO), and while air pollution is already a major risk factor, worsening air quality will worsen the disease burden due to NCDs further. 

Dr Soumya Swaminathan, fomer WHO Chief Scientist.

“The evidence base on the health impacts of air pollution in India is growing. There is a fair amount of data now on the adverse effects of poor air quality on not only respiratory diseases like asthma and COPD [chronic obstructive pulmonary disease], but also cardiovascular and neurological diseases, as well as an increase in metabolic disorders like diabetes mellitus,” former WHO chief scientist Dr Soumya Swaminathan told Health Policy Watch.

“The impact is particularly serious among pregnant women and young children, because it affects the growing organs of the fetus and young child and is likely to have permanent effects on physical and cognitive development,” added Swaminathan, who recently became co-chairperson of Our Common Air (OCA), a new global commission that has been launched by Clean Air Fund (CAF) in London, and the Council on Energy, Environment and Water (CEEW) in New Delhi. 

[MS Swaminathan Research Foundation] has recently completed a study on the impacts of climate change on women and children in India, where air pollution is one of the major considerations and the evidence has all been collated,” she said of the foundation started by her father that she now chairs.

There are now around 500 studies on the impact of air pollution on health in India, according to Palak Balyan who leads the research team at Climate Trends, a Delhi-based research consultancy. 

She added that some gaps persist as the availability of health data is limited and most of the research comes from clusters around key cities like Delhi and Chennai, but not as much from the country’s rural areas.

Globally there were 8.1 million deaths due to air pollution in 2021.

Shocking and counter-intuitive statistics 

A few statistics that have emerged from recent research have been shocking and some even counter-intuitive, Swaminathan said. 

“The fact that women who stay mostly indoors [in cities] are often exposed to a higher dose of air pollutants than men who work outdoors. This has been documented in a study from Delhi… The fact that life expectancy in parts of north India is reduced by as much as five to seven years because of poor air quality,” she said. 

Indoor air pollution in the developing world is linked to the lack of access to clean cooking fuels, and the health impacts that research has highlighted would have takeaways for other developing countries in similar situation around Asia, Africa and Latin America.   

Swaminathan added that it is also becoming clear that air pollution affects not just the respiratory system but also distant organs like the heart, blood vessels and the brain, which is alarming. 

The State of the Global Air report 2024 listed air pollution as the second largest risk factor of deaths in 2021 after hypertension. However air pollution is also known to worsen hypertension.

Air pollution was the second largest risk factor of deaths in 2021.


“Globally, it is established that exposure to air pollution is a major risk factor for hypertension,” said Professor Sagnik Dey from the Centre for Atmospheric Sciences at the Indian Institute of Technology in Delhi. Most of this research is in developed countries but research from India is also emerging on this connection.

All the countries in the top five most polluted in the world are low-and middle-income countries with low resources and high hypertension burden. 

Dey added that initiatives like the India Hypertension Control Initiative focus on screening programmes which have a place but improving air quality will have to go with it. 

“We have strong evidence that additionally if India really works towards clean air, there will be a much accelerated progress and much larger health benefit,” Dey said.

Remaining research gaps

Establishing the health impacts of air pollution requires robust health data, and Balyan said most of the India-based research uses credible health data sourced from the country’s National Family and Health Survey (NFHS) which offers a representative sample. 

But this data is secondary data, and while there are studies that use primary data from communities, getting this data can be challenging. 

Even when the patients come into the health system, often this data is not captured as healthcare professionals are spread thin.
“Doctors are not trained or equipped with this kind of knowledge and also they don’t have this much of time to devote to each patient. When they ask patients’ history they rarely go to the any kind of questions which relates the problem of that patient to environmental stress or occupational stress,” Balyan said. 

Dey also added that a key gap is that often that the health and environment departments work in silos.

Enough evidence to act

Despite the difficulties of gathering primary data, there is enough compelling evidence both globally and on the India level for policy makers to act. 

Currently China, India and Pakistan top the list of the countries with the most number of air pollution deaths, according to the State of the Global Air report 2024

India recently re-elected Prime Minister Narendra Modi’s government for the third time. Issues related to health, climate and environment were rarely brought up by his government or the opposition during the election campaign. But India’s air quality has not shown any significant improvement in the past half a decade despite allocation of budgets, and in fact has worsened in some pockets, as Health Policy Watch reported earlier. 

Experts said improvements in air quality will be followed by health gains for the local communities. 

“Many cities around the world have improved air quality in relatively short time-periods and have seen positive impacts on health very quickly. Investing in air quality will have huge pay-offs for health and also for the economy,  and should be a high priority for all governments,” Swaminathan said. 

Image Credits: Flickr, State of Global Air Report 2024.

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