Air pollution protective measures at personal-level affecting health outcomes: A systematic review and meta-analysis

Background: Evidence for the effect of health-protective measures from air pollution at the individual level is relatively scarce. We performed a systematic review and meta-analysis to investigate the effect of personal protective measures for air pollution on various health outcomes. Methods: We searched PubMed, Scopus, and Web of Science to find randomized controlled trial studies investigating the effect of personal protective measures for air pollution on health outcomes. Two authors independently searched and selected studies, extracted information, and assessed each study's quality and risk of bias. Meta-analyses were performed when three or more studies were available for specific pair of protective measure and health outcome. Results: Lung function was higher in groups applying air purifiers than control groups with sham/no filter: forced expiratory volume in 1 second (FEV1) by 0.25 L [95% confidence intervals (CI): 0.01, 0.49]. The application of air-purifying respirators was associated with increased heart rate variability: the root mean square of successive differences between normal heartbeats (rMSSD) by 0.36 (95% CI: 0.13, 0.59). For other pairs of measures and health outcomes, evidence was insufficient. Conclusion: Our findings suggest that air purifiers and air-purifying respirators can serve as an efficient protective measure for respiratory and cardiovascular health, respectively. Key Words: air pollution, personal-level protective measures