Outdoor air pollution and hospitalizations for ischemic heart disease: a systematic review and meta-analysis

Abstract

Objective: The study aimed to evaluate the association between six major outdoor air pollutants (i.e., PM2.5, PM10, NO2, SO2, CO, and O3) and the risk of ischemic heart disease (IHD)-attributable hospitalization to provide potential scientific evidence for the formulation of clinical and public health policies. Methods: Using the PubMed and Web of Science databases (up to March 2025), the present meta-analysis screened and included 17 high-quality studies (three cohort studies (CS), one case–control study (CC), and 13 time-series studies (TS)) covering 28,186,905 cases hospitalized for IHD. This study focused on the determination of the impact of air pollutant concentration changes on the risk of IHD-attributable hospitalization using statistical analysis in Stata 16.0. In addition, sensitivity analyses and funnel plots were employed to assess stability and publication bias. Results: The meta-analysis revealed the following associations between the air pollutants and IHD-attributable hospitalization: PM2.5: [RR = 1.01 (95% confidence interval (CI):1.00 ~ 1.01), p = 0.000], PM10: [RR = 1.01 (95%CI:1.00 ~ 1.01), p = 0.000], NO2: [RR = 1.02 (95%CI: 1.00 ~ 1.03), p = 0.000], SO2: [RR = 1.01 (95%CI: 1.00 ~ 1.02), p = 0.001], CO: [RR = 1.04 (95%CI: 0.97 ~ 1.12), p = 0.01], and O3: [RR = 1.00 (95%CI: 1.00 ~ 1.00),p = 0.000]. Conclusion: High concentrations of air pollutants may significantly contribute to an increased risk of IHD-attributable hospitalization. The present study identifies air pollution as a major modifiable cardiovascular risk factor that should be integrated into clinical cardiovascular disease (CVD) management and public health policy formulation.