Published: September 11, 2020
There is limited evidence on the association between long-term air pollution exposure and the risk of allergic sensitization in children beyond primary school age.
In a multicenter study recently published in The Journal of Allergy & Clinical Immunology (JACI), Melén et al. hypothesized that air pollution exposure may contribute to the development of allergic sensitization in children up to adolescent age, and that timing of exposure might be of importance. They used data collected on more than 6,000 children from four European studies followed from birth up to 15-16 years of age. The children performed blood tests for antibodies (IgE, immunoglobulin E) to common inhalant and food allergen extracts. Additionally, IgE against 132 allergen molecules were measured in a subgroup of children. Outdoor levels of several air pollution indicators (e.g., PM2.5 and NO2) were modelled according to a standardized exposure assessment protocol and assigned to the birth addresses and those where study participants resided at the time of blood sampling.
The prevalence of sensitization to any of the tested inhalant and/or food allergen extracts ranged between 24% - 40% at the age of 4-6 years, 35% - 48% at the age of 8-10 years, and 42% - 51% at 15-16 years across the studies. The combined results indicated that air pollution exposure was generally not associated with IgE sensitization. However, analyses based on specific IgE to allergen extracts suggested increased risks of sensitization to birch in relation to several air pollution indicators. Further, higher air pollution exposure at birth address was associated with elevated IgE levels of the grass allergen molecule Phl p 1, as well as the cat allergen molecule Fel d 1.
This study is one of the first to assess effects of air pollution on the development of allergic sensitization throughout childhood up to adolescent age based on combined analyses of prospective studies with a large sample size, using a meta-analytic approach. The authors’ findings provide new insights into the role of early-life air pollution exposure for sensitization to specific allergen molecules later in life.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.