Traffic-related air pollution and incident asthma in a high-risk birth cohort

Area of Science:

• Environmental Health
• Pediatric Respiratory Medicine
• Epidemiology

Background:

• The impact of early-life exposure to traffic-related air pollution (TRAP) on asthma development remains incompletely understood.
• A high-risk birth cohort provides a valuable model for investigating the nuanced relationship between TRAP and childhood respiratory conditions.

Purpose of the Study:

• To investigate the association between birth year exposure to specific traffic-related air pollutants and the incidence of asthma and bronchial hyper-reactivity.
• To test the hypothesis that increased TRAP exposure in early life elevates the risk of new-onset asthma.

Main Methods:

• Recruitment of infants from a high-risk asthma birth cohort.
• Estimation of birth year exposures to nitrogen monoxide (NO), nitrogen dioxide (NO2), black carbon, and fine particulate matter (PM2.5) using land use regression.
• Assessment of asthma and bronchial hyper-reactivity at age 7 via clinical evaluation and methacholine challenge, with statistical analysis adjusted for confounders.

Main Results:

• An interquartile range increase in birth year PM2.5 was significantly associated with a 3.1-fold increased risk of asthma (95% CI 1.3 to 7.4) and a trend towards increased bronchial hyper-reactivity.
• Similar positive associations were observed for nitrogen monoxide (NO) and nitrogen dioxide (NO2) exposures.
• Black carbon exposure did not show a significant association with increased asthma or bronchial hyper-reactivity risk.

Conclusions:

• Elevated exposure to certain traffic-related air pollutants during the first year of life is associated with the development of new-onset asthma by age 7.
• The study's findings underscore the utility of high-risk birth cohorts and precise exposure/outcome data in revealing significant environmental health associations, even with smaller sample sizes.