Residential Proximity to Major Roadways and Risk of Allergic Respiratory Outcomes: A Systematic Review and Meta-analysis

With the acceleration of global urbanization, residential proximity to major roadways (RPMR) has been recognized as a significant threat to public health, while the association between road proximity and risks of allergic respiratory outcomes remains unclear. This study aims to evaluate the associations between RPMR and the risks of allergic respiratory outcomes. We conducted a systematic literature search for existing scientific literature from databases of PubMed, EMBASE, Web of Science, Cochrane, and Scopus. The study protocol was registered at PROSPERO (registration ID: CRD42024604182). Random effects models were applied to evaluate the associations between RPMR and the risks of allergic respiratory outcomes by calculating the pooled odds ratio (OR) and corresponding 95% confidence interval (CI). During the study periods, 55 eligible studies were included, comprising 373,320 participants. We found that a close RPMR (≤ 200 m) was associated with increased risks of asthma (OR = 1.23, 95% CI: 1.15, 1.31), wheezing (OR = 1.21, 95% CI: 1.12, 1.30), and rhinitis (OR = 1.22, 95% CI: 1.13, 1.32). In addition, we identified that the closer the RPMR, the higher the risks for allergic respiratory outcomes. The observed associations between RPMR and allergic respiratory outcomes were more pronounced among children and less urbanized areas than in adults and highly urbanized areas. Our study provides comprehensive evidence for the associations between RPMR and risks for allergic respiratory outcomes. The findings may contribute to the practical implications for urban planning and public health strategies to mitigate exposure to traffic-related pollution.