Long-term exposure to air pollution is killing millions of people in India, according to a new study conducted by researchers at Sweden’s Karolinska Institute.

Published in The Lancet Planetary Health, the research calls for urgent action to tighten air quality regulations across the country.

The study focused on smaller air pollution particles called PM2.5, which are smaller than 2.5 micrometers in diameter. These particles can penetrate deep into the lungs and enter the bloodstream, causing serious health risks.

Using data from 655 districts across India between 2009 and 2019, researchers linked PM2.5 levels to mortality.

The study found that every 10 microgram per cubic meter increase in PM2.5 levels led to an 8.6% increase in deaths. Over a decade, about 3.8 million deaths were caused by air pollution levels that exceeded India’s air quality guideline of 40 micrograms per cubic metre.

The figures become even more dire when compared to the strict guidelines of the World Health Organization (WHO), which recommend a limit of only 5 micrograms per cubic meter.

Using this benchmark, the study estimates that 16.6 million deaths – or about a quarter of all deaths during the study period – could be linked to air pollution.

The shocking thing is that every single person in India lives in areas where PM2.5 levels exceed WHO guidelines.

In some areas, concentrations reached 119 micrograms per cubic metre, about 24 times the WHO’s safe limit.

“Current air quality guidelines in India are not sufficient to protect health. Stricter regulations and decisive measures to cut emissions are urgently needed,” said lead researcher Petter Ljungman of Karolinska Institutet.

While India’s National Air Pollution Control Program launched in 2017 aims to improve air quality, PM2.5 levels continue to rise in many parts of the country.

In 2019, the lowest level of PM2.5 (11.2 micrograms per cubic metre) was recorded in Lower Subansiri district of Arunachal Pradesh. The highest level (119.0 micrograms per cubic metre) was found in Ghaziabad, Uttar Pradesh and Delhi in 2016.

During the study period, the number of deaths linked to air pollution increased from 4.5 million in 2009 to 7.3 million in 2019.

The Swedish researchers stressed that local emissions reductions should be combined with strategies to tackle long-range air pollution, as PM2.5 particles can travel hundreds of kilometers.

“This study provides important evidence to support the creation of stronger air quality policies in India and globally,” Ljungman said.

In 2019, the Global Burden of Disease Study estimated that nearly one million deaths in India were caused by outdoor air pollution. However, this estimate was based on data from countries with very low pollution levels, which may not be applicable to India.

So, the researchers used data from India to study how long-term exposure to PM2.5 particles affects overall mortality, using a method focused on finding cause-and-effect relationships.

With approximately 1.4 billion people breathing polluted air throughout the year, the study underlines the urgent need for action to tackle air pollution and its devastating impact on public health.