Prenatal Air Pollution Exposure and the Development of Allergic Sensitization in Early Life: A Randomized Controlled Trial

摘要

Background: Prenatal exposure to PM2.5 has been associated with the development of allergic sensitization in children. We conducted a randomized controlled trial in Ulaanbaatar, Mongolia to test whether reducing PM2 5 with HEPA filter air cleaners during pregnancy reduced the risk of allergic symptoms in infancy. Methods: Women were enrolled at 10.3 weeks gestation, on average. Mothers who were randomly assigned to the intervention (N = 217) received one or two air cleaners (depending on home size) to use from enrollment until childbirth. Women assigned to the control group (N = 187) received no air cleaners. We measured indoor PM_(2.5) concentrations over 7-days at ～ 10 weeks gestation and again at -30 weeks gestation with Dylos particle counters. We used questionnaires to ascertain the presence of eczema, wheeze, respiratory infections and otitis media in infancy. The efficacy of the intervention was analyzed in intention-to-treat analyses. Results: Baseline characteristics were similar between the two groups. PM_(2.5) concentrations were 28% lower, on average, in intervention homes than control homes (GM: 17.3 vs. 24.4 μg/m3). The prevalence of outcomes ranged from 5% for wheeze to 54% for eczema. Evidence of a protective effect was seen only for wheeze (OR: 0.62, 95% CI: 0.28 - 1.38) , while the risk of eczema was slightly higher in the intervention group (OR: 1.43, 95% CI: 0.87 - 2.39) . Otitis media and respiratory infections were similar between groups. Conclusion: HEPA air filter air cleaners significantly reduced indoor PM2.5 concentrations during pregnancy. Our results do not provide strong support for the hypothesis that air cleaner use during pregnancy reduces risks of allergic symptoms in infancy.