Ambient particulate matter and chronic obstructive pulmonary disease mortality: a nationwide, individual-level, case-crossover study in China

Background Short-term exposure to particulate matter air pollution has been associated with the exacerbations of COPD, but its association with COPD mortality was not fully elucidated. We aimed to assess the association between short-term particulate matter exposure and the risk of COPD mortality in China using individual-level data. Methods We derived 2.26 million COPD deaths from a national death registry database in Chinese mainland between 2013 and 2019. Exposures to fi ne particulate matter (PM2.5) 2.5 ) and coarse particulate matter (PM 2.5-10 ) were assessed by satellite-based models of a 1 x 1 km resolution and assigned to each individual based on residential address. The associations of PM 2.5 and PM 2.5-10 with COPD mortality were examined using a time-stratified fi ed case-crossover design and conditional logistic regressions with distributed lag models. We further conducted stratified fi ed analyses by age, sex, education level, and season. Findings Short-term exposures to both PM 2.5 and PM 2.5-10 were associated with increased risks of COPD mortality. These associations appeared and peaked on the concurrent day, attenuated and became nonsignificant fi cant after 5 or 7 days, respectively. The exposure-response curves were approximately linear without discernible thresholds. An interquartile range increase in PM 2.5 and PM 2.5-10 concentrations was associated with 4.23% (95% CI: 3.75%, 4.72%) and 2.67% (95% CI: 2.18%, 3.16%) higher risks of COPD mortality over lag 0-7 - 7 d, respectively. The associations of PM 2.5 and PM 2.5-10 attenuated slightly but were still significant fi cant in the mutual-adjustment models. A larger association of PM 2.5-10 was observed in the warm season. Interpretation This individual-level, nationwide, case-crossover study suggests that short-term exposure to PM 2.5 and PM 2.5-10 might act as one of the environmental risk factors for COPD mortality. Funding This study is supported by the National Key Research and Development Program of China (2023YFC3708304 and 2022YFC3702701), the National Natural Science Foundation of China (82304090 and 82030103), the 3-year Action Plan for Strengthening the Construction of the Public Health System in Shanghai (GWVI-11.2-YQ31), and the Science and Technology Commission of Shanghai Municipality (21TQ015). Copyright (c) 2024 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).