Atmospheric PM2.5 exposure and risk of ischemic heart disease: A systematic review and meta-analysis of observational studies

Fine particulate matter <2.5 mu m in diameter (PM2.5) has been validated to associate with cardiovascular diseases (CVD) incidence and mortality. So far, no study has quantitatively evaluated the relationship between the atmospheric PM2.5 exposure and ischemic heart disease (IHD). We conducted a meta-analysis to illustrate the relationship between PM2.5 and IHD. Published articles were systematically searched (until June 2022) from PubMed, EMBASE, Cochrane Library. A random-effect model was performed to summarize the total relative risks (RRs) and 95% confidence intervals (CIs). Meta-analysis was performed using Stata 12.0 software. A total of 28 studies among 23 cohorts (23.38 million individuals and 256256 IHD cases) were included. With PM2.5 increasing 10 mu g/m(3), the total RRs of IHD incidence and mortality were 1.07 (95% CI: 0.99-1.17), 1.21 (95% CI: 1.15-1.28), respectively. In sub-analyses, our study revealed that the combined RRs of exposure to PM2.5 on IHD mortality in Asian and European population [1.11 (95% CI: 0.93-1.33); 1.06 (95% CI: 1.02-1.11)] were much lower compared with American and Canadian people [1.27 (95% CI: 1.17-1.37); 1.30 (95% CI: 1.24-1.35)]. Furthermore, study duration, size and some adjustments were related with the total RR. Our findings indicated that exposure of an increase in the concentration of atmospheric PM2.5 may increase the risk of IHD incidence and mortality. Further evidence is needed to confirmed the association.