Fine Particulate Air Pollution and Daily Mortality. A Nationwide Analysis in 272 Chinese Cities

Evidence concerning the acute health effects of air pollution caused by fine particulate matter (PM_2.5) in developing countries is quite limited.

To evaluate short-term associations between PM_2.5 and daily cause-specific mortality in China.

A nationwide time-series analysis was performed in 272 representative Chinese cities from 2013 to 2015. Two-stage Bayesian hierarchical models were applied to estimate regional- and national-average associations between PM_2.5 concentrations and daily cause-specific mortality. City-specific effects of PM_2.5 were estimated using the overdispersed generalized additive models after adjusting for time trends, day of the week, and weather conditions. Exposure-response relationship curves and potential effect modifiers were also evaluated.

The average of annual mean PM_2.5 concentration in each city was 56 μg/m³ (minimum, 18 μg/m³; maximum, 127 μg/m³). Each 10-μg/m³ increase in 2-day moving average of PM_2.5 concentrations was significantly associated with increments in mortality of 0.22% from total nonaccidental causes, 0.27% from cardiovascular diseases, 0.39% from hypertension, 0.30% from coronary heart diseases, 0.23% from stroke, 0.29% from respiratory diseases, and 0.38% from chronic obstructive pulmonary disease. There was a leveling off in the exposure-response curves at high concentrations in most, but not all, regions. The associations were stronger in cities with lower PM_2.5 levels or higher temperatures, and in subpopulations with elder age or less education.

This nationwide investigation provided robust evidence of the associations between short-term exposure to PM_2.5 and increased mortality from various cardiopulmonary diseases in China. The magnitude of associations was lower than those reported in Europe and North America.