Effects of short-term exposure to ambient airborne pollutants on COPD-related mortality among the elderly residents of Chengdu city in Southwest China.

BACKGROUND

Chronic obstructive pulmonary disease (COPD) has become a severe global burden in terms of both health and the economy. Few studies, however, have thoroughly assessed the influence of air pollution on COPD-related mortality among elderly people in developing areas in the hinterland of southwestern China. This study is the first to examine the association between short-term exposure to ambient airborne pollutants and COPD-related mortality among elderly people in the central Sichuan Basin of southwestern China.

METHODS

Data on COPD-related mortality among elderly people aged 60 and older were obtained from the Population Death Information Registration and Management System (PDIRMS). Data on airborne pollutants comprised of particulate matter < 2.5 μm in aerodynamic diameter (PM), sulfur dioxide (SO), nitrogen dioxide (NO), carbon monoxide (CO), and ozone (O) were derived from 23 municipal environmental monitoring sites. Data on weather conditions, including daily mean temperature and relative humidity, were obtained from the Chengdu Meteorological Bureau. All data were collected from January 1, 2015, to December 31, 2018. A quasi-Poisson general additive model (GAM) was utilized to assess the effects of short-term exposure to airborne pollutants on COPD-related mortality among elderly people.

RESULTS

A total of 61,058 COPD-related deaths of people aged 60 and older were obtained. Controlling the influences of daily temperature and relative humidity, interquartile range (IQR) concentration increases of PM (43 μg/m), SO (8 μg/m), NO (18 μg/m), CO (0.4 mg/m), and O (78 μg/m) were associated with 2.7% (95% CI 1.0-4.4%), 4.3% (95% CI 2.1-6.4%), 3.6% (95% CI 1.7-5.6%), 2.7% (95% CI 0.6-4.8%), and 7.4% (95% CI 3.6-11.3%) increases in COPD-related mortality in people aged 60 and older, respectively. The exposure-response curves between each pollutant and the log-relative risk of COPD-related mortality exhibited linear relationships. Statistically significant differences in the associations between pollutants and COPD-related mortality were not observed among sociodemographic factors including age, gender, and marital status. The effects of O remained steady after adjusting for PM, SO, NO, and CO each time in the two-pollutant models.

CONCLUSIONS

Increased concentrations of ambient airborne pollutants composed of PM, SO, NO, O, and CO were significantly and positively associated with COPD-related mortality in the central Sichuan Basin, which is located in the hinterland of southwestern China. The adverse effects of O were stable, a finding that should receive more attention.