Association of Ambient Air Pollution with Blood Pressure in Adolescence: A Systematic-review and Meta-analysis

We systematically reviewed the association of ambient air pollution with blood pressure (BP) as a primary outcome in adolescents (10-19 years). Five databases (Ovid Medline, Ovid Embase, Web of Science, The Cochrane Library, and LILACS) were searched for relevant articles published up to August 2022. Meta-analyses were conducted using STATA v17 (Protocol - OSF Registries https://doi.org/10.17605/OSF.IO/96G5Q). Eight studies (5 cohort, 3 cross-sectional) with approximately 15,000 adolescents were included. Data from 6 studies were suitable for inclusion in the meta-analyses. In sub-group analyses, non-significant positive associations were observed for cohort studies assessing long-term exposure to PM10, PM2.5, and NO2 on systolic and diastolic BP. At age 12 years old (3702 adolescents), we found significant positive associations for long-term exposure to PM2.5(beta=5.33 (1.56, 9.09) mmHg) and PM10 (beta=2.47 (0.10, 4.85) mmHg) on diastolic BP. Significant positive associations were observed (3,592 adolescents) for long-term exposure to PM10(beta=0.34 (0.19, 0.50) mmHg) and NO2 on diastolic BP (beta=0.40 (0.09, 0.71) mmHg), and PM10 on systolic BP (beta=0.48 (0.19, 0.77) mmHg). The overall quality of evidence analysed was graded as "low/very low." Insufficient data for short-term exposures to PM2.5, PM10, NO2, CO on BP led to their exclusion from the meta-analysis. Inconsistent associations were reported for gender-stratified results. The evidence, though of low-quality and limited, indicated that ambient air pollution was positively associated with adolescent BP. Future studies need improved measures of air pollutant exposures, consideration of gender and socio-economic circumstances on the observed pollution effects, as well as adjustment for other potential confounding factors.