Air Pollution from Traffic and the Development of Respiratory Infections and Asthmatic and Allergic Symptoms in Children

TLDR

Traffic sources significantly affect urban air quality, yet few studies have examined their impact on childhood asthma and other respiratory diseases. This study investigated the link between traffic‑related air pollution and the development of asthmatic/allergic symptoms and respiratory infections in a Dutch birth cohort of about 4,000 children. Researchers used a validated model to estimate home outdoor concentrations of nitrogen dioxide, PM2.5, and soot, and analyzed questionnaire data on wheezing, cough, ENT infections, skin rash, and physician‑diagnosed asthma, bronchitis, influenza, and eczema at age two. Positive associations were found between traffic‑related pollutants and wheezing, physician‑diagnosed asthma, ear/nose/throat infections, and flu/serious colds, with some borderline significance, while no links were seen for other outcomes; sensitivity analyses suggested stronger effects for early‑diagnosed asthma, though confirmation at older ages is needed.

Abstract

Despite the important contribution of traffic sources to urban air quality, relatively few studies have evaluated the effects of traffic-related air pollution on health, such as its influence on the development of asthma and other childhood respiratory diseases. We examined the relationship between traffic-related air pollution and the development of asthmatic/allergic symptoms and respiratory infections in a birth cohort (n ∼ 4,000) study in The Netherlands. A validated model was used to assign outdoor concentrations of traffic-related air pollutants (nitrogen dioxide, particulate matter less than 2.5 μm in aerodynamic diameter, and “soot”) at the home of each subject of the cohort. Questionnaire-derived data on wheezing, dry nighttime cough, ear, nose, and throat infections, skin rash, and physician-diagnosed asthma, bronchitis, influenza, and eczema at 2 years of age were analyzed in relation to air pollutants. Adjusted odds ratios for wheezing, physician-diagnosed asthma, ear/nose/throat infections, and flu/serious colds indicated positive associations with air pollutants, some of which reached borderline statistical significance. No associations were observed for the other health outcomes analyzed. Sensitivity analyses generally supported these results and suggested somewhat stronger associations with traffic, for asthma that was diagnosed before 1 year of age. These findings are subject to confirmation at older ages, when asthma can be more readily diagnosed.