This study aimed to conduct a meta-analysis to investigate whether short-term exposure to fine (PM2.5) and coarse (PM10) particulate matter was associated with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) hospitalization, emergency room visit, and outpatient visit at different lag values. PubMed, Embase, and the Cochrane Library were searched for relevant papers published up to March 2021. For studies reporting results per 1-µg/m3 increase in PM2.5, the results were

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... culated as per 10-µg/m3 increase. We manually calculated the RRs for these two studies and transferred the RRs to estimate 10 µg/m3 increases in PM2.5. Automation tools were initially used to remove ineligible studies. Two reviewers independently screened the remaining records and retrieved reports. Twenty-six studies (28 datasets; 7,018,419 patients) were included. There was a significant association between PM2.5 and AECOPD events on lag0 (ES = 1.01, 95%CI: 1.01-1.02, p 2=88.6%, Pheterogeneity<0.001), lag1 (ES = 1.00, 95%CI: 1.00-1.01, p 2=82.5%, Pheterogeneity<0.001), lag2 (ES = 1.01, 95%CI: 1.01-1.01, p 2=90.6%, Pheterogeneity<0.001), lag3 (ES = 1.01, 95%CI: 1.00-1.01, p 2=88.9%, Pheterogeneity<0.001), lag4 (ES = 1.00, 95%CI: 1.00-1.01, p 2=83.7%, Pheterogeneity<0.001), and lag7 (ES = 1.00, 95%CI: 1.00-1.00, p 2=0.0%, Pheterogeneity=0.743). The subgroup analyses showed that PM2.5 influenced the rates of hospitalization, emergency room visits, and outpatient visits. Similar trends were observed with PM10. The risk of AECOPD events (hospitalization, emergency room visit, and outpatient visit) was significantly increased with a 10-µg/m3 increment in PM2.5 and PM10 from lag0 to lag7. List Of Abbreviations: particulate matter (PM2.5 and PM1 [...]