Environment & Health Seminar: Environmental Factors Affecting Stress in Children: Interrelationships Between Traffic-Related Noise, Air Pollution, and Built Environment.

Meredith Franklin, Associate Professor, University of Southern California

Abstract: A growing body of research suggests that stressors such as traffic-related noise, air pollution and artificial light at night may be directly and indirectly associated with decrements in children’s mental health. On the other hand, living near greenspace can reduce stress and provide other health benefits for children. When aged 13-14 and 15-16 years, participants in the Southern California Children’s Health Study cohort participants residing in eight densely populated urban communities responded to detailed questionnaires regarding perceived stress. Exposures of artificial light at night (ALAN) derived from satellite observations, near-roadway air pollution (NRP) from a dispersion model, noise from the U.S. Traffic Noise Model, and greenspace from satellite observations of Enhanced Vegetation Index (EVI) were linked to each participant’s geocoded residence. Among the 2290 children in this study, girls (50% [n=1149]) had significantly higher perceived stress measured by PSS-4 (mean [SD]) (5.7 [3.34) than boys (4.9 [3.2]). With increasing age (13.5 [0.6] to 15.3 [0.6] years), stress rose from 5.6 [3.3] to 6.0 ([3.4]) in girls but decreased for boys from 5.0 [3.2] to 4.7 ([3.1]). Multivariate mixed effects models examining multiple exposures indicated that exposure to secondhand smoke in the home was associated with a 0.85 (95% CI 0.46, 1.24) increase in PSS-4, and of factors related to the physical environment, an interquartile range (IQR) increase in ALAN was associated with a 0.57 (95% CI 0.05, 1.09) unit increase in PSS-4, together with a 0.16 increase (95% CI 0.02, 0.30) and a -0.24 decrease (95% CI -0.45, -0.04) per IQR of NRP and EVI, respectively. Income modified the ALAN effect estimate; participants in households earning <$48,000 had significantly greater stress per IQR increase in ALAN. Sleep duration partially mediated the associations between stress and both EVI and ALAN by 17% and 18%, respectively. Perceived stress increased most with exposure to smoke at home in addition to residential exposure to artificial light at night and near-roadway air pollution. These associations were partially dampened by more residential greenspace. Our findings support the promotion of increased residential green spaces in order to reduce pollution associated with the built environment as it could have significant mental health benefits for children.

Brief Bio: Meredith Franklin is an Associate Professor of Biostatistics at the University of Southern California. She holds a BSc in Mathematics from McGill University and a PhD in Environmental Science and Statistics from Harvard University. Broadly, her research straddles the fields environmental statistics and epidemiology. She specializes in statistical methods for exposure assessment with a focus on modeling multiple pollutants characterizing the built environment. She has conducted several seminal studies of the association between air pollution and mortality and morbidity, and recently has been focused on characterizing complex multipollutant mixtures to examine their joint roles on a variety of health outcomes.

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