Aims: The association of long-term ambient air pollution and hypertension has been inconsistently reported. We performed an updated systematic review and meta-analysis to assess the association between long-term exposure to ambient air pollution and risk of hypertension in adults and in children.
Methods: PubMed, EMBASE, and Web of Science were searched up to August 7, 2020 for published articles examining the association of long-term exposure to ambient air pollution, including particulate matter (PM; ultrafine particles, PM1, PM1-2.5, PM2.5, PM2.5-10 and PM10), nitrogen dioxide (NO2), nitrogen oxides (NOx), sulfur dioxide (SO2), ozone (O3), carbon monoxide (CO) and hypertension. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) for hypertension with each 10-μg/m3 increase in air pollutants were calculated by random-effects models.
Results: We included 57 studies (53 of adults and 4 of children) in the meta-analysis. Risk of hypertension was significantly increased in adults with each 10-μg/m3 increase in exposure to PM2.5 (OR 1.10, 95% CI 1.07-1.14; I2 = 93.1%; n = 37), PM10 (1.04, 1.02-1.07; I2 = 44.8%; n = 22), and SO2 (1.21, 1.08-1.36; I2 = 96.6%; n = 3). Hypertension was not significantly associated with PM1 (n = 2), PM2.5-10 (n = 16), NO2 (n = 27), or NOx (n = 17). In children, the summary ORs (95% CIs) for each 10-μg/m3 increase in PM2.5, PM10, SO2 and O3 were 2.82 (0.51-15.68; I2 = 83.8%; n = 2), 1.15 (1.01-1.32; I2 = 0; n = 2), 8.57 (0.13-575.58; I2 = 94.2%; n = 2), and 1.26 (0.81-1.09, I2 = 91.6%; n = 2), respectively.
Conclusions: Long-term ambient air pollution is a potential risk factor for hypertension in adults. More studies are needed to explore the effects of long-term air pollution on hypertension in children.
Keywords: Ambient air pollution; Hypertension; Long-term; Meta-analysis.
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