Estimating the Causal Effect of Annual PM 2· 5 Exposure on Mortality in India

摘要: Background: In 2019, the Global Burden of Disease attributed 0· 98 million deaths to ambient air pollution in India based on potentially inappropriate exposure-response functions from countries with low air pollution levels. Instead, using Indian data, we investigated long-term exposure to particulate matter measuring< 2.5 micrograms (PM 2· 5) and all-cause mortality using a causal inference method.Methods: We collected national counts of annual mortality from 2009 to 2019 and obtained annual PM 2· 5 concentrations from a high-resolution spatiotemporal model. We applied an extended version of the difference-in-differences design by using generalized additive models with quasi-Poisson distribution including indicator variables and separate time trends for spatial administrative divisions.Findings: The annual median population-weighted PM 2· 5 was 38· 9 µg/m 3 (5th and 95th percentiles 19· 7 and 71· 8 µg/m 3 respectively). The full population lived in areas exceeding WHO guidelines and 81· 9% of the population in areas above the Indian National Ambient Air Quality Standards (NAAQS)(< 40 ug/m 3). A 10 µg/m 3 increase in annual PM 2· 5 was associated with a 6· 0%(95% CI 3· 9, 8· 3) higher annual mortality. In comparison to the Indian NAAQS, a total of 5· 5 million deaths (95% CI 3· 6, 6· 8) between 2009-2019 were attributable to PM 2· 5, amounting to 8· 5% of total mortality (95% CI 5· 5, 10· 3).Interpretation: Our causal modelling approach allowed us to assess the full extent of registered deaths in the world’s most populated country with high levels of air pollution. We provide new evidence of increased mortality risk from long-term PM 2 …