Methodological lessons and pilot data on the effect of proximity of homes and schools to highways on pediatric asthma and lung function

Abstract

Numerous studies have found that either living or attending school near highways or exposure to pollutants associated with heavy motor vehicle traffic are associated with a high prevalence of asthma and reduced lung function. Yet, few investigations have assessed school and home exposure in the same study. We recruited children aged 5-19 years from a pediatric clinic in an urban center (Boston Chinatown) for many of whom housing and school were located immediately adjacent to two major highways. A questionnaire was used to assess self-report of diagnosis of asthma and the proximity of schools and homes to highways, as well as basic demographic information. Spirometric lung function data were obtained and reviewed by a pediatric pulmonologist blinded to survey responses. During this review, we excluded lung function tests of low quality. The analyses did not demonstrate any associations or mean differences between near-highway exposure at school, at home, or both with diagnosed asthma (p>0.10, n=124). For the lung function data (n=87), neither direct measures (FEV1, FVC, and FEF(25-75)) nor ratio measures (FEV1/FVC and FEF(25-75)/FVC) had a significant association with near-highway exposure (p>0.10). Certain predisposing factors, such as diagnosed allergies and family history of asthma, were strongly associated with diagnosed asthma (p<0.05 and p=0.001, respectively), findings we have seen consistently in other work with children recruited from the same clinic. We also found that exposure to pests was significantly correlated with a smaller FEF(25-75)/FVC ratio (p=0.02). Our findings suggest that either limitations in our study design restricted our ability to see the associations reported by others or that such associations do not exist in this population. One possibility is that in this community, with heavy street traffic and many street canyons, the gradient of exposure next to the highway is not very well delineated by simple proximity.