Abstract Body (Do not enter title and authors here): Background: Fine particulate matter (PM2.5), a principal component of air pollution, has been increasingly implicated as a critical environmental risk factor for cardiovascular diseases (CVDs). Despite substantial evidence from individual studies, inconsistencies remain across systematic reviews and meta-analyses regarding the magnitude, dose-response relationship, and modifiers of PM2.5-associated cardiovascular risks.
Objectives: This umbrella review synthesizes and critically evaluates and synthesizes the existing systematic reviews and meta-analyses on the association between PM2.5 exposure and cardiovascular health outcomes.
Methods: Following PRISMA guidelines, a comprehensive search was conducted across PubMed, Scopus, Web of Science, Cochrane Library, Embase, and Google Scholar. Eligible studies included systematic reviews and/or meta-analyses examining PM2.5 exposure in relation to CVD morbidity, mortality, or relevant biomarkers in human populations. Methodological quality was appraised using the AMSTAR 2 tool.
Results: A total of 38 eligible systematic reviews and meta-analyses were included, encompassing studies across multiple continents and diverse populations. The evidence consistently supports a significant association between both short- and long-term PM2.5 exposure and increased risk of cardiovascular events, including myocardial infarction, stroke, heart failure, and cardiovascular mortality. Risk estimates varied but indicated a dose-dependent relationship, with some reviews reporting elevated risks even at PM2.5 concentrations below current WHO/variousnational guidelines. Subgroup analyses identified heightened vulnerability among older adults, individuals with preexisting cardiovascular conditions, and populations in low- and middle-income countries. Methodological quality varied, with most reviews rated as moderate to high confidence. Key limitations included heterogeneity in exposure assessment and insufficient data from underrepresented regions.
Conclusions: This umbrella review affirms the robust and consistent association between PM2.5 exposure and adverse cardiovascular outcomes. The findings underline the urgent need for stricter air quality standards and targeted public health interventions, especially in high-risk populations. Further high-quality research is warranted to elucidate the roles of specific PM2.5 constituents and co-pollutants, as well as to inform evidence-based policy decisions.