Ambient particulate matter is one of the main risk factors of chronic obstructive pulmonary disease (COPD) in developing countries. However, the studies were scant in China concerning the health effects of the fine particulate matter (PM2.5; particulate matter ≤ 2.5 μm in diameter) on hospital visits for COPD. We applied a generalized additive model (GAM) to calculate relative risks (RRs) with 95% confidence intervals (CIs) for the associations between hospital visits for COPD and an interquartile range (24.50 μg/m3) increment of ambient PM2.5 concentrations in Yinzhou District between 2016 and 2018. The ambient PM2.5 concentration was positively associated with hospital visits for COPD at a distributed lag of 0-7 days (RR = 1.073, 95% CI, 1.016, 1.133). In the stratified analysis, we found that the association between ambient PM2.5 and COPD was stronger during the warm season (April to September) than that during the cold season (October to March), but we did not observe statistically significant differences in age groups (< 60 years and ≥ 60 years) or gender groups (male and female) related to the effects of PM2.5. The associations between ambient PM2.5 and COPD became partially attenuated after the adjustment for gaseous pollutants in subgroups. Our findings could provide evidence that regulations for controlling both PM2.5 and gaseous pollutants should be implemented to protect the overall population.
Keywords: Air pollution; COPD; Generalized additive model; Hospital visits; PM2.5; Time-series study.