Acute exposure to elevated air pollution and cause-specific mortality: A causal modeling study from 2012 to 2018 in central Indo-Gangetic Plain

Abstract

We applied inverse probability weighting (IPW) causal modeling with multiple air pollutants (PM_2.5, O₃, and NO₂), meteorological parameters, and potential lag effect of exposures to estimate the marginal effect of short-term exposure to air pollution (AP) on cause-specific mortality risks in the Indo-Gangetic Plain (IGP). A causal linkage between short-term exposure to PM_2.5 and O₃ was found with all four assessed causes of deaths (viz. neurological, respiratory, cardiovascular, and nephrological deaths), whereas NO₂ was found to have a linkage only with the cardiovascular mortality risks; for every 10-ppb increase in NO₂ exposure, the mean risk increased by 0.84percent (95percent Uncertainty interval (UI) = 0.58, 1.10). For every 10 microg m^-3 increase in short-term PM_2.5 exposure, the increase in the risk of in-hospital all-cause deaths, neurological deaths, respiratory deaths, cardiovascular deaths, and nephrological deaths was 1.76percent (1.57, 1.95), 0.28percent (0.07, 0.50), 0.73percent (0.47, 0.98), 0.72percent (0.48, 0.96), and 0.11percent (0.09, 0.14), respectively. Likewise, after controlling PM_2.5 and NO₂, the causation between acute exposure to O₃ and respiratory mortality risk was found to be highest among all scenarios studied; for every 10-ppb increase in O₃ there was a 2.24percent increase in the respiratory death risk (2.02, 2.45). This set of results from IPW causal modeling could serve as the causational evidence documenting relative risk (RR) estimates of premature cause-specific mortalities attributable to ambient AP in a subset of Indian population.