Every 10 unit rise in annual PM2.5 exposure raising death risk in Indians: Study

New Delhi, Dec 12: Every 10 micrograms per cubic metre of air increase in annual exposure to fine particulate matter 2.5 (PM2.5) is associated with an 8.6 per cent increased risk for mortality across India, finds a study on Thursday. The study, published in the journal Lancet Planetary Health, revealed that long-term exposure to PM2.5 pollution concentrations higher than the 5 micrograms per cubic meter annual average recommended by the WHO is potentially associated with 1.5 million deaths a year in India.

The findings showed that the 1.4 billion people in India live in areas with PM2.5 concentrations above that recommended by the WHO guidelines. "High levels of annual PM2.5 exposures are observed in India causing a huge mortality burden not limited to cities that are highlighted during the extreme pollution episodes, signaling the need for systematic and not symptomatic approach,” said Suganthi Jaganathan, doctoral researcher, Centre for Health Analytics Research and Trends (CHART), Ashoka University.

The study observed that the risk is high even at lower levels of air pollution. This indicates the need to reduce air pollution levels across the country. Unlike previous studies, this study used PM2.5 exposure from a fine spatio-temporal model built for India and annual mortality counts reported across all districts of India.

During the study period (2009 to 2019), 25 per cent of all deaths about 1.5 million deaths a year were attributed to annual PM2.5 exposure higher than the WHO guideline. About 0.3 million annual deaths are also attributed to annual exposure to PM2.5 above the Indian National Ambient Air Quality Standards (NAAQS). The exposure response function revealed a higher incremental risk for mortality at lower PM2.5 concentrations and leveling off at higher PM2.5 concentrations.

“Delhi may get the headlines, but this is a problem all over India, and nationwide efforts are needed. Coal burning electric plants need scrubbers, crop burning needs to be limited, and most importantly, we need urgent measures to protect population health,” said Joel Schwartz, Professor, Harvard T.H. Chan School of Public Health and principal investigator from the US for the CHAIR-India consortium.

The study was led by the CHAIR-India consortium, established in May 2019, comprised of leading Indian academic institutions such as the Centre for Health Analytics Research and Trends (CHART) at Ashoka University, the Centre for Chronic Disease Control (CCDC) and global institutions like Karolinska Institute (Stockholm, Sweden), Harvard University, Boston University, among others.