Air pollution exposure and allergic sensitization in children: a meta-analysis of five European birth cohorts within the ESCAPE project

Abstract

Background: The evidence on long-term effects of air pollution exposure on childhood allergy is limited. Objective: We investigated the association between air pollution exposure and allergic sensitization to common allergens in children followed prospectively during the first 10 years of life. Methods: Five European birth cohorts participating in the ESCAPE project were included: BAMSE (Sweden), LISAplus and GINIplus (Germany), MAAS (Great Britain) and PIAMA (The Netherlands). Land-use regression models were applied to assess the individual residential outdoor levels of particulate matter with aerodynamic diameter <2.5 ?m (PM2.5), 2.5-10 ?m (PMcoarse), and <10 ?m (PM10); PM2.5 absorbance, nitrogen dioxide, and nitrogen oxides (NOx). Blood samples drawn at 4-6 and/or 8-10 years from more than 6500 children were analyzed for allergen-specific serum IgE against common allergens. Associations were assessed by multiple logistic regression, and subsequent meta-analysis. Results: Overall, air pollution exposure was not associated with sensitization to any common allergen, with odds ratios ranging from 0.94 (95% CI, 0.63–1.40) for 1×10-5 m-1 increase in PM2.5 absorbance to 1.26 (0.90-1.77) for 5 µg/m3 increase in PM2.5 exposure at birth address. However, subgroup analyses suggested a higher risk of sensitization in relation to air pollution exposure among boys (OR for PM2.5 exposure at birth address: 1.62 (95% CI, 1.05-2.50)) and in children who did not change address since birth (1.68, 95% CI, 1.03–2.75) for exposure to PM2.5 absorbance. Conclusion: No clear associations between air pollution exposure and development of allergic sensitization in children up to 10 years of age were revealed.