Association between long-term exposure to PM2.5 and hypertension: A systematic review and meta-analysis of observational studies

Numerous studies have examined the association between long-term exposure to particulate matter with an aerodynamic diameter of ≤2.5 μm (PM2.5) and hypertension. However, the results are inconsistent. Considering the limitations of previous meta-analyses and the publication of many new studies in recent years, we conducted this meta-analysis to assess the relationship between long-term PM2.5 exposure and the incidence and prevalence of hypertension in a healthy population. We searched PubMed, Web of Science, Embase, and Scopus for relevant studies published until April 2, 2021 and reviewed the reference lists of previous reviews. A total of 28 observational studies reporting RR or OR with 95% CI for the association between long-term PM2.5 exposure and the risk of hypertension were included. After the sensitivity analysis, we excluded one study with a high degree of heterogeneity, resulting in 27 studies and 28 independent reports. Approximately 42 million participants were involved, and the cases of hypertension in cohort and cross-sectional studies were 508,749 and 1,793,003, respectively. The meta-analysis showed that each 10 μg/m3 increment in PM2.5 was significantly associated with the risks of hypertension incidence (RR = 1.21, 95% CI: 1.07, 1.35) and prevalence (OR = 1.06, 95% CI: 1.03, 1.09). Subgroup analyses showed that occupational exposure had a significant effect on the association of PM2.5 and hypertension incidence (p for interaction = 0.042) and that the PM2.5 concentration level and physical activity had a noticeable effect on the association of PM2.5 and hypertension prevalence (p for interaction = 0.005; p for interaction = 0.022). A significantly positive correlation was observed between long-term PM2.5 exposure and risks of hypertension incidence and prevalence, and a high PM2.5 concentration resulted in an increased risk of hypertension. •Long-term exposure to PM2.5 is positively related to hypertension incidence and prevalence.•Occupational exposure affects the relationship between PM2.5 and hypertension incidence.•PM2.5 concentration level and physical activity affect the association of PM2.5 and hypertension prevalence.•10 cohort studies and 17 cross-sectional studies with more than 42 million people were included.•Our meta-analysis was oriented to the entire population (children, youth, adults, and elderly).