Associations between ambient air pollutants and blood pressure among children and adolescents: A systemic review and meta-analysis.

Abstract Objective Numerous epidemiological studies have investigated the effects of short-term and long-term exposure to ambient air pollution on hypertension and blood pressure among children and adolescents. However, the results were controversial. To provide researchers reliable evidence, this meta-analysis was performed. Methods We searched all published studies in four databases examining the effects of particulate matter (PM10, PM2.5 and PM1.0), nitrogen oxide (NO2), sulfur dioxide (SO2), ozone (O3) and carbon monoxide (CO) on hypertension and blood pressure in children and adolescents. Overall risk estimates associated with per 10 μg/m3 increase of air pollution were analyzed by a random-effect model for articles with significant heterogeneity, otherwise, a fixed-effect model was applied. Subgroup analysis was conducted for studies with significant heterogeneity. Results Of 3918 identified literatures, 154 were evaluated in-depth with 15 satisfying inclusion criteria. Increased risk of hypertension was associated with long-term PM10 exposure (OR = 1.17, 95% confidence interval [CI]:1.13, 1.21). For systolic blood pressure (SBP), significant results were found for short-term PM10 (β = 0.26, 95% CI: −0.00, 0.53) exposure, long-term PM2.5 (β = 1.80, 95% CI: 0.94, 2.65) and PM10 (β = 0.50, 95% CI: 0.19, 0.81) exposure. The corresponding estimates of diastolic blood pressure (DBP) were 0.32 mmHg (95% CI: 0.19, 0.45) for short-term PM10 exposure, 1.06 mmHg (95% CI: 0.32, 1.80), 0.34 mmHg (95% CI: 0.11, 0.57) and 0.44 mmHg (95% CI: 0.25, 0.63) for long-term PM2.5, PM10 and NO2 exposure, respectively. Stratified analyses showed stronger effects of PM10 on blood pressure among studies with ≥50% boys' percentage (0.57 mmHg [95% CI: 0.44, 0.70] for SBP, 0.44 mmHg, [95% CI: 0.34, 0.54] for DBP, respectively) and articles using models to estimate exposure (0.90 mmHg [95% CI: 0.20 1.59] for SBP). Conclusion Ambient air pollution was associated with higher hypertension prevalence and elevated blood pressure in children and adolescents.