Air pollution in India linked to millions of deaths

A new study from Karolinska Institutet shows that long-term exposure to air pollution contributes to millions of deaths in India. The research, published in The Lancet Planetary Health, emphasises the need for stricter air quality regulations in the country.

Air pollution consisting of particles smaller than 2.5 micrometres in diameter, PM2.5, can enter the lungs and bloodstream and is a major health risk in India. Researchers have now examined the link between these particles and mortality over a ten-year period. The study is based on data from 655 districts in India between 2009 and 2019.

“We found that every 10 microgram per cubic metre increase in PM2.5 concentration led to an 8.6 percent increase in mortality,” says Petter Ljungman, last author and researcher at the Institute of Environmental Medicine at Karolinska Institutet.

The research analysed the relationship between changes in air pollution levels and mortality. The results show that around 3.8 million deaths over the period can be linked to air pollution levels above India's own air quality guidelines of 40 micrograms per cubic metre.

When compared to the stricter guidelines recommended by the World Health Organisation (WHO) - only 5 micrograms per cubic metre - the figure rises to 16.6 million deaths. That's almost 25 per cent of all mortality during the study period.

The study also highlights that the entire population of India lives in areas where PM2.5 levels exceed WHO guidelines. This means that almost 1.4 billion people are exposed year after year to air pollution that can negatively affect health. In some regions, levels of up to 119 micrograms per cubic metre were measured, significantly higher than what both the WHO and India consider safe.

“The results show that current guidelines in India are not sufficient to protect health. Stricter regulations and measures to reduce emissions are of utmost importance,” said Petter Ljungman.

The Indian government has been running a national air pollution control programme since 2017 to improve air quality, but the study shows that PM2.5 concentrations have continued to increase in many areas. The researchers emphasise the importance of both reducing emissions locally and taking into account the long range of air pollution - PM2.5 particles can travel hundreds of kilometres.

“Our study provides evidence that can be used to create better air quality policies, both in India and globally,” says Petter Ljungman.

The study was funded by Formas. The study is a collaboration between researchers from universities in India, Sweden, USA, Israel and Italy.

Publication: ‘Estimating the effect of annual PM2-5 exposure on mortality in India: a difference-in-differences approach’, Suganthi Jaganathan, Massimo Stafoggia, Ajit Rajiva, Siddhartha Mandal, Shweta Dixit, Jeroen de Bont, Gregory A Wellenius, Kevin J Lane, Amruta Nori-Sarma, Itai Kloog, Dorairaj Prabhakaran, Poornima Prabhakaran, Joel Schwartz, Petter Ljungman, The Lancet Planetary Health, online December 11, 2024, doi: 10.1016/S2542-5196(24)00248-110