Effects of Short-term Exposure to Ambient Airborne Pollutants on COPD-related Mortality Among the Elderly Residents of Chengdu City in Southwest China
Authors: Chen Jianyu , Shi Chunli , Li Yang , Ni Hongzhen , Zeng Jie , Lu Rong , Zhang Li 
Published: August 2020

Abstract
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 higher elevation areas. 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 (PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) 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 PM2.5 (43 µg/m3), SO2 (8 µg/m3), NO2 (18 µg/m3), CO (0.4 mg/m3), and O3 (78 µg/m3) were associated with 1.9%, 3.4%, 2.7%, 2.5%, and 3.8% 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 associations between COPD-related mortality and pollutants in the 60–69 age group were not observed but were observed in the ≥ 90 age group, with the exception of CO. Correspondingly, statistically significant associations between COPD-related mortality and PM2.5 were only observed in the ≥ 90 age group. Statistically significant differencesin the associations between pollutants and COPD-related mortality were not observed between males and females or between married individuals and those with alternative marital statuses (widowed, divorced, or never married).The effects of O3 remained steady after adjusting for PM2.5, SO2, NO2, and CO each time in the two-pollutantmodels.Conclusions: Increased concentrations of ambient airborne pollutants composed of PM2.5, SO2, NO2, O3, and CO were significantly and positively associated with COPD-related mortality in the central Sichuan Basin of southwestern China, which has an elevation of 500 meters. Susceptibilities to COPD-related mortality associated with ambient airborne pollutants may increase with age. The adverse effects of O3 were stable, a finding that should receive more attention.