Long-term exposure to fine particulate matter relates with incident myocardial infarction (MI) risks and post-MI mortality: A meta-analysis

Air pollution has become a global challenge, and a growing number of studies have suggested possible relationships between long-term exposure to fine particulate matter (PM2.5) and risks of cardiovascular events, specifically, myocardial infarction (MI). However, the recently reported results were inconsistent. We thus performed a meta-analysis and sought to assess whether long-term exposure to PM2.5 relates with incident MI risks and post-MI mortality. EMBASE, Web of Science and PubMed were searched for all potentially eligible studies published before August 2, 2020 using a combination of keywords related to PM2.5 exposure, its long-term effects and myocardial infarction. Key information was extracted, and calculated hazard ratio (HR) values were combined by selecting corresponding models according to heterogeneity test. A sensitivity analysis and a publication bias assessment were also performed to determine the reliability of the results. Of the initially identified 2100 citations, 12 studies met our inclusion criteria and observed a total population of approximately 7.2 million. Pooled estimates (per 10 μg/m3 increase) indicated a statistically significant association between long-term PM2.5 exposure and MI incidence (HR = 1.10, 95% CI: 1.02–1.18) or post-MI mortality (HR = 1.07, 95% CI: 1.04–1.09). Results for MI incidence from Egger’s linear regression method (P = 0.515) and Begg’s test (P = 0.711) showed no obvious publication bias. Our quantitative analysis reveals a significant link between long-term PM2.5 exposure and greater MI incidence risks or higher post-MI mortality. Our findings may therefore have implications for individual protection and policy support to improve public health.