Air Pollution Is Associated With Persistent Peanut Allergy in the First 10 Years

To assess whether exposure to air pollution is associated with eczema and food allergies in the first 10 years of life.This was a substudy of the HealthNuts study, a longitudinal, population-based cohort study focused on understanding the prevalence, risk factors, natural history, and burden of food allergy and other allergic diseases in children. For the HealthNuts study, 5276 patients were recruited in infancy from 2007 to 2011 from immunization sessions in Australia. All participants underwent skin prick testing (SPT) and blood ImmunoCAP testing for common food allergens and, when positive, oral food challenge (OFC) to confirm clinical food allergy. Follow-up visits occurred when the participants were aged 4, 6, and 10 years.For this part of the HealthNuts study, 4668 infants were enrolled at age 1 year. Those with SPT greater than or equal to 1 mm to peanut or egg were offered OFC to confirm clinical food allergy, defined as positive OFC and SPT greater than or equal to 2 mm and/or specific immunoglobulin E greater than or equal to 0.35 KU/L. Positive OFC was defined to have at least 1 of the following: (1) 3 or more noncontact hives simultaneously that continued for at least 5 minutes, (2) perioral or periorbital or angioedema, (3) vomiting, or (4) anaphylaxis (circulatory or respiratory involvement) occurring within 2 hours of ingestion of a dose during food challenge or home-based introduction. SPT and OFC were repeated at age 4, 6, and 10 years. Annual average fine particulate matter (PM2.5-diamater of ≤2.5 μm) and nitrogen dioxide (NO2) levels were measured at geocoded residential addresses of the participants. High levels of NO2 were defined as greater than or equal to 10 ppb. Increased PM2.5 was defined per 1.2-μg/m3 increase. At age 1 year, eczema was defined by parent report of physician’s diagnosis of eczema or rash with topical steroid prescription.Infants exposed to high concentrations of NO2 at age 1 year had higher peanut allergy prevalence at ages 1 (adjusted odds ratio [95% CI], 2.21 [1.40–3.48]) and 4 years (2.29 [1.28–4.11]). High exposure to NO2 at age 6 years was associated with higher peanut allergy prevalence at 6 years (1.34 [1.00–1.82] per 2.7-ppb NO2 increase). Similarly, increased PM2.5 at age 1 year was associated with peanut allergy at ages 4, 6, and 10 years (respectively, 1.27 [1.01–1.60], 1.27 [1.01–1.56], and 1.46 [1.05–2.04] per 1.2-μg/m3 PM2.5 increase).Exposure to higher concentrations of air pollution, as defined by PM2.5 and NO2 in early life, was associated with the presence and persistence of OFC-proven peanut allergy. There was little evidence of association between air pollution and egg allergy or eczema in this cohort. Previous animal models had suggested that air pollution may act as an adjuvant to airborne peanut allergens to promote peanut allergy.This evidence highlights the importance of early-life interventions aimed at reducing exposure to air pollutants, which could potentially decrease or prevent peanut allergies. Further studies could provide important information that may aid in our understanding about the impact of pollution on the development atopy.