Respiratory Emergency Department Visit Associations with Exposures to Fine Particulate Matter Mass, Constituents, and Sources in Dhaka, Bangladesh Air Pollution.

To date, there is no published local epidemiological evidence documenting the respiratory health effects of source-specific air pollution in South Asia, where particulate matter ⩽2.5 μm in aerodynamic diameter (PM) composition is different from past studies. Differences include more biomass and residue crop-burning emissions, which may have differing health implications. We assessed PM associations with respiratory emergency department (ED) visits in a biomass-burning-dominated high-pollution region and evaluated their variability by pollution source and composition. Time-series regression modeling was applied to daily ED visits from January 2014 through December 2017. Air pollutant effect sizes were estimated after addressing long-term trends and seasonality, day of week, holidays, relative humidity, ambient temperature, and the effect modification by season, age, and sex. PM yielded a significant association with increased respiratory ED visits (0.84%; 95% confidence interval, 0.33-1.35%) per 10-μg/m increase. The PM health effect size varied with season, the highest being during monsoon season, when fossil-fuel combustion sources dominated exposures. Results from a source-specific health effect analysis were also consistent with fossil-fuel PM having a larger effect size per 10 μg/m than PM from other sources (fossil-fuel PM: 2.79% [0.33-5.31%], biomass-burning PM: 1.27% [0-2.54%], and other PM: 0.95% [0.06-1.85%]). Age-specific associations varied, with children and older adults being disproportionately affected by the air pollution, especially by the combustion-related particles. This study provided novel and important evidence that respiratory health in Dhaka is significantly affected by particle air pollution, with a greater health impact by fossil-fuel combustion-derived PM.