Major findings: Every 10 μg/m3 increase in annual PM2.5 exposure is associated with an 8.6% increased risk for mortality across India. 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. First Indian study to use difference-in-difference method, a causal methodology to isolate the effect of long-term PM2.5 exposure (annual) and all-cause mortality. During the study period (2009 to 2019), 25% of all deaths (~1.5 million deaths a year) were attributed to annual PM2.5 exposure higher than the WHO guideline value of 5 μg/m3 across the country. About 0.3 million annual deaths are attributed to annual exposure to PM2.5 above the Indian National Ambient Air Quality Standards (NAAQS). The exposure-response function revealed higher incremental risk for mortality at lower PM2.5 concentrations and levelling off at higher PM2.5 concentrations.
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