Food and airborne allergies among children (not in daycare) increased by 61% for each 10 μg/m3 increase in nitrogen dioxide. 2,477 children were included and assessed for inhaled or food allergies at approximately one year of age. Researchers determined the mother's exposure during pregnancy to traffic related air pollution. While no increase in child allergy was noted from the pregnant mother's air pollution exposure, it was found infants exposed to elevated nitrogen dioxide after birth experienced higher rates of allergy. Nitrogen dioxide is an inflammatory gas produced during combustion of gasoline vehicles and known for its irritation and damage potential in the lungs.
ABSTRACT
Background
The role of traffic-related air pollution (TRAP) exposure in the development of allergic sensitization in children is unclear, and few birth cohort studies have incorporated spatiotemporal exposure assessment.
Objectives
We aimed to examine the association between TRAP and atopy in 1-year-old children from an ongoing national birth cohort study in four Canadian cities.
Methods
We identified 2,477 children of approximately 1 year of age with assessment of atopy for inhalant (Alternaria, Der p, Der f, cat, dog, cockroach) and food-related (milk, eggs, peanuts, soy) allergens. Exposure to nitrogen dioxide (NO2) was estimated from city-specific land use regression models accounting for residential mobility and temporal variability in ambient concentrations. We used mixed models to examine associations between atopy and exposure during pregnancy and the first year of life, including adjustment for covariates (maternal atopy, socioeconomic status, pets, mold, nutrition). We also conducted analyses stratified by time-location patterns, daycare attendance, and modeled home ventilation.
Results
Following spatiotemporal adjustment, TRAP exposure after birth increased the risk for development of atopy to any allergens [adjusted odds ratio (aOR) per 10 μg/m3 NO2 = 1.16; 95% CI: 1.00, 1.41], but not during pregnancy (aOR = 1.02; 95% CI: 0.86, 1.22). This association was stronger among children not attending daycare (aOR = 1.61; 95% CI: 1.28, 2.01) compared with daycare attendees (aOR = 1.05; 95% CI: 0.81, 1.28). Trends to increased risk were also found for food (aOR = 1.17; 95% CI: 0.95, 1.47) and inhalant allergens (aOR = 1.28; 95% CI: 0.93, 1.76).
Conclusion
Using refined exposure estimates that incorporated temporal variability and residential mobility, we found that traffic-related air pollution during the first year of life was associated with atopy.