Air pollution and IgE sensitization in four European birth cohorts - the MeDALL project.

Abstract Background Whether long-term air pollution exposure has effects on allergic sensitization is controversial. Objective To investigate associations of air pollution exposure at birth and at the time of later biosampling, with IgE sensitization against common food/inhalant allergens, or specific allergen molecules, in children up to 16 years. Methods Up to 6163 children from four European birth cohorts participating in the MeDALL Consortium were included in this meta-analysis: BAMSE (Sweden), LISA/GINIplus (Germany), and PIAMA (The Netherlands). Individual residential outdoor levels of particulate matter with aerodynamic diameters Results Air pollution was not consistently associated with IgE sensitization to any common allergen extract up to 16 years. However, allergen-specific analyses suggested increased risks of sensitization to birch: OR=1.12; 95% CI: 1.01–1.25 per 10 μg/m3 increase in NO2 exposure. In a sub-population with microarray data, IgE to the major timothy grass allergen Phl_p_1 and cat allergen Fel_d_1 >3.5 ISU-E were related to PM2.5 exposure at birth (OR=3.33; 1.40-7.94, and 4.98; 1.59-15.60, respectively, per 5 μg/m3 increase in exposure). Conclusion Air pollution exposure does not seem to increase the overall risk of allergic sensitization, however, sensitization to birch as well as grass pollen Phl_p_1 and cat Fel_d_1 allergen molecules may be related to specific pollutants.