Association of traffic-related pollution and stress on childhood lung function

UnrestrictedBackground: Studies have shown that decreased lung function is predictive of various health outcomes including asthma, heart disease, and death. Although there are some inconsistencies in the literature, many studies have shown that exposure to various types of air pollutants negatively impact lung growth in children and adults. Furthermore, there is some evidence that social stress may also be of importance in the understanding of respiratory health; however, no studies have explored the joint relationship between lung function, air pollution, and stress. The aims of this study are to further explore the relationship between childhood lung function and air pollution, specifically traffic-related pollutants (TRPs), and to assess the potential modifying effects of parental stress.; Methods: A total of 1,811 children from a new southern Californian Children’s Health Study cohort participated in lung function testing during the sixth year of the study. Forced vital capacity (FVC), forced expiratory volume during the first second (FEV1), maximal mid-expiratory flow (MMEF) and peak expiratory flow rates (PEFR) were measured at each of the 44 participating schools. Various metrics of TRP were used including distance to road and two different types of model-based estimates of pollutant concentration. The first set of modeled TRP estimates were based on the CALINE4 line-source air-quality dispersion model, which took into account local traffic information and meteorological conditions. The other set of TRP are predicted residential exposures of NO2, NO, and NOx that incorporated population demographics and topography in addition to local traffic information. Parental perceived stress and other covariates were collected through questionnaire.; Results: Close proximity to a major road was found to be negatively associated with both FEV1 and FVC, while close proximity to a freeway was negatively associated with only FVC. Among all children, no observed associations were found with CALINE4 predicted exposures. However with respect to the 10th-90th percent distribution, predicted residential NO was associated with a 1.4% deficit in FEV1 and a 2% deficit in FVC (per 7.6 ppb). Similarly, predicted residential NOx was associated with a 1.3% deficit in FEV1 and a 1.9% deficit in FVC (per 21.9 ppb), while residential NO2 was associated with a 1.7% deficit in FVC (per 14.5 ppb). The impact of various TRPs was more pronounced among children whose parents were classified as being highly stressed. Over the same distribution of predicted residential exposures to NO, NOx, and NO2, these children experienced a 3.3%, 3.6%, and 3.6% deficit in FEV1, respectively, while for children in lower stress homes, these pollutants had little impact. Similar findings were also observed with respect to the non-freeway component of CALINE4-modeled TRP and distance to a major road as well as when FVC was chosen as the outcome. Effect modification by parental stress was statistically significant in all of these examples. No statistically significant associations of TRP were found with MMEF and PEFR.; Discussion: These findings suggest that exposure to traffic-related pollutants negatively impacts the development of children’s lungs. Furthermore, living in a high stress household potentiates the adverse effects of these residential traffic-related pollutants