Assessment of the mortality burden associated with ambient air pollution in rural and urban areas of India

2018-04-26Background: In India, more than a billion people are at risk from ambient particulate matter (PM) concentrations exceeding World Health Organization air quality guidelines, posing serious threat to health. Previous studies, conducted in the United States, have elucidated increases in all-cause and specific-cause mortality associated with exposure to PM in metropolitan cities. Associations between mortality and ambient particulate matter exposure are poorly characterized for India, despite its serious air pollution problem. ❧ Methods: In this study, using 2009-2015 data from the Central Pollution Control board (CPCB) and Civil Registration System (CRS), we investigated the association between exposure to fine and coarse PM air pollutants (PM₂.₅ and PM₁₀, respectively) with all-cause mortality, targeting both rural and urban centers in India. Spatial statistical methods including variograms and universal kriging, were applied to annual averages of PM data from 222 districts to generate exposure estimates at unobserved locations. The estimated exposures were linked to annual counts of all-cause mortality in the respective districts, and the associations between annual average PM₂.₅ and PM₁₀ and mortality were determined using Poisson regression. Sex, occupation, literacy, geographic location, and year were all considered as potential confounders and were included in the model. ❧ Results: There was 7.7% (95% confidence interval = 7.4% - 7.8%) increase in all-cause mortality associated with a 10 μg/m³ increase in annual averaged PM₁₀ concentration across districts in India. This association was larger in urban areas (16.7% [16.3% - 16.9%]) than in the rural areas (4.6% [4.2% - 4.8%]). Similarly, with a 10 μg/m³ increase in an annual average PM₂.₅ concentration, there was 23.2% (95% confidence interval = 23.0% - 23.3%) increase in all-cause mortality. This association was adjusted by combination of covariates such as literacy, occupational workers, household size, geographical location and year, which were also aggregated at a district level. ❧ Conclusion: This study shows that after controlling for certain demographic factors, geographic location and year there is a statistical significant increase in mortality with increase in PM exposures