A new study from Karolinska Institute 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.
Researchers found that every 10 microgram per cubic metre increase in PM2.5 concentration led to an 8.6 percent increase in mortality.
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 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.
The entire 1·4 billion people in the Indian population lived in areas with PM2·5 concentrations above that recommended by the WHO guidelines, and 1·1 billion of 1·4 billion (81·9% of the total population) lived in areas above the Indian NAAQS. The national population-weighted median PM2·5 per district was 38·9 μg/m3 (5–95th percentile 19·7–71·8 μg/m3) for the whole study period. Researchers estimated that every 10 μg/m3 increment in PM2·5 was associated with an 8·6% increase in risk for all-cause mortality, with annual average PM2·5 concentrations in Indian districts ranging between 11·2 μg/m3 and 119·0 μg/m3. Scientists estimated that 1·5 million (95% CI 1·1–1·9) deaths occurred annually due to long-term exposure to PM2·5 in India every year in excess of the 5 μg/m3 that is recommended by the WHO ambient air quality guidelines. Although the WHO recommendation is substantially lower than the current air pollution levels in India, even when considering the Indian NAAQS the 0·3 million (95% CI 0·2–0·4) annual attributable deaths across the country is still alarmingly high.
Study provides evidence that can be used to create better air quality policies, both in India and globally.
Source: The Lancet Planetary Health, 2024; 8 (12): e987 DOI: 10.1016/S2542-5196(24)00248-1