Effect of Traffic-Related Air Pollution on Allergic Disease: Results of the Children's Health and Environmental Research

PURPOSE This study evaluated the relationship of living near to main roads to allergic diseases, airway hyperresponsiveness (AHR), allergic sensitization, and lung function in Korean children. METHODS A total of 5,443 children aged 6-14 years from 33 elementary schools in 10 cities during 2005-2006 were included in a baseline survey of the Children's Health and Environmental Research. We assessed association of traffic-related air pollution (TAP) exposure with the distance to the nearest main road, total road length of main roads and the proportion of the main road area within the 200-m home area. RESULTS Positive exposure-response relationships were found between the length of the main road within the 200-m home area and lifetime wheeze (adjusted prevalence ratio [PR] for comparison of the longest to the shortest length categories=1.24; 95% CIs, 1.04-1.47; P for trend=0.022) and diagnosed asthma (PR=1.42; 95% CIs, 1.08-1.86; P for trend=0.011). Living less than 75 m from the main road was significantly associated with lifetime allergic rhinitis (AR), past-year AR symptoms, diagnosed AR, and treated AR. The distance to the main road (P for trend=0.001), the length of the main road (P for trend=0.041), and the proportion of the main road area (P for trend=0.006) had an exposure-response relationship with allergic sensitization. A strong inverse association was observed between residential proximity to the main load and lung function, especially FEV1, FEV1/FVC, and FEF₂₅₋₇₅. The length of the main road and the proportion of the main road area were associated with reduced FEV1 in schoolchildren. CONCLUSIONS The results of this study suggest that exposure to traffic-related air pollution may be associated with increased risk of asthma, AR, and allergic sensitization, and with reduced lung function in schoolchildren.