Association of exposure to ambient particulate matter with asthma in children: Systematic review and meta-analysis

Objective: To assess the association between airborne particulate matter (PM) exposure and the development of asthma in children, a systematic review and meta-analysis that included nearly 10 years of related literature was conducted. Study Design: The study investigators conducted a systematic review of relevant research articles published between March 2013 and March 2023, which were accessible through several medical literature data bases of. Random-effects meta-analyses were used to analyze the effects of PM on childhood asthma. Subgroup analyses, including exposure period, type of PM, regional factors, and study type, were also used. Odds ratio (OR) and 95% confidence intervals (CI) were used to represent the estimated effect of the population. Publication bias was assessed by using the Egger test and funnel plot. Data analyses were performed using statistical analysis software and a systematic review management tool. Results: A total of 15,365 articles were identified, of which 19 studies were included in this meta-analysis. The results showed that PM exposure was positively correlated with asthma in children, with the overall random-effects risk estimates of OR 1.10 (95% CI, 1.07-1.13). In stratified analyses, PM exposure was found to be a risk factor for the development of childhood asthma. Both prenatal and postnatal PM exposure were associated with an increased risk of asthma in children, but prenatal exposure was associated with a greater increase in risk than postnatal exposure, with an effect estimate OR of 1.21 (95% CI, 1.02-1.43). In the analysis of different PM types, the OR of PM_2.5 (PM < 2.5 μm in diameter) exposure was OR 1.10 (95% CI, 1.05-1.15), and no association was found between PM₁₀ (PM < 10 μm in diameter), coarse PM (PM with an aerodynamic diameter between 2.5 and 10 μm), and black carbon BC (diameter of 0.01-0.05 μm) exposure. In different regional analyses, the effects of PM exposure on childhood asthma risk were OR 1.15 (95% CI, 1.13-1.17) in South America and OR 1.02 (95% CI, 1.01-1.03) in Asia, but no association was found in Europe and North America. In addition, the results of different study types only found that the literature that used the time-series research method had a significant association with OR 1.03 (95% CI, 1.02-1.04), whereas the literature that used the cohort study method had no statistical difference. Conclusion: Exposure to airborne PM increased the risk of asthma in children. Both prenatal and postnatal PM exposure was associated with an increased risk of childhood asthma, but prenatal PM exposure was associated with a greater increase than postnatal PM exposure.