Background and aims: Traffic related air pollutants from diesel engine exhaust are found in fine and ultrafine particulates. The Cincinnati Childrens Allergy and Air Pollution Birth Cohort Study was initiated to determine if early exposure to these pollutants increased risk for development of early atopic sensitization and allergic respiratory disease phenotypes in children.
Materials and methods: Over 700 infants born to at least one atopic parent were recruited to participate in a birth cohort study. Participants received annual medical evaluations and skin testing to two foods and 15 aeroallergens from ages 1-4 and again at age seven. Indoor home assessments were conducted at age one. Outdoor traffic related air pollutant exposure was estimated using proximity and land use regression (LUR) modeling. Clinical outcomes were based upon case definitions for wheezing at ages one and three and allergic rhinitis at age three.
Results: At age 1 exposure to stop and go traffic was associated with wheezing during infancy and recurrent wheezing was twice more likely among African-American infants. Exposure to high levels of elemental carbon attributable to traffic (ECAT) estimated with a LUR model predicted recurrent wheezing at age 1 as well as multiple wheezing phenotypes at age 3. Exposure to high levels of endotoxin combined with multiple dogs during the first year reduced risk for recurrent wheezing during the first year of life. Early sensitization to tree pollen aeroallergens in foods (egg white, milk) in infancy increased likelihood of allergic rhinitis during age 3.
Conclusion: High exposure to traffic related air pollutants represent independent risk factors for wheezing during infancy and early childhood. Further studies are needed to explore long-term effects of traffic exposure on development of asthma in childhood. Scientific significance. Reduction and mitigation of exposure to traffic related air pollutants could reduce risk of respiratory illnesses during childhood.