In new work published in the Annals of the American Thoracic Society we analyzed the links between where children are physically active and their exposure to air pollution and lung function. Physical activity is associated with increased ventilation because of rapid and deeper breathing. Thus, being active while being exposed to high air pollution could lead to increased inhalation of pollutant particles and gases. In urban communities features of the built environment, including locations where children engaging in physical activity, could put individuals at risk for harmful inhaled exposures leading to lung function decrements. Thus, we conducted a study to investigate locations throughout New York City where children engaged in moderate-vigorous activity. Our hypothesis was that being physically active outdoors, particularly near high sources of traffic pollution, would be associated with increased air pollution exposure and decreased lung function.
Our study was conducted as part of a longitudinal birth cohort study in affiliation with the Columbia Center for Children’s Environmental Health that recruited pregnant, non-smoking mothers who lived in Northern Manhattan and the Bronx. At the time of enrollment in this secondary study, children were 9-14 years of age and still lived in NYC. The 151 children enrolled in the study wore global positioning system (GPS) devices in a vest to identify their locations and accelerometers on their wrists that measured physical activity level. Devices were worn for 24-hours with repeated measures after 5 days. We paired the GPS and accelerometer data and mapped the data using ArcGIS to determine where children engaged in moderate-vigorous activity. We also used data from the New York City Community Air Survey (NYCCAS) to determine annual average air pollution concentrations in the locations where children were physically active. To account for daily fluctuations in pollution we adjusted our analysis for daily NYC pollution measured at a single site as well as daily temperature and humidity. Lastly, we measured lung function at the end of each 24-hour physical activity monitoring period.
On average, children spent more time physically active indoors (71.9 ±74.7 min/day) compared to outdoors (38.2 ±39.6 min/day). However, the majority of outdoor physical activity was along sidewalks and roadbeds (30.2 ±33.3 min/day) where nitrogen dioxide (NO2) pollution was relatively high. More time spent in outdoor activity was associated with higher exposure to NO2. In warmer months, more time spent in outdoor activity was associated with lower lung function even after adjusting for air pollution exposure. This finding suggests that in addition to air pollution there may be other environmental factors that contribute to decreased lung function when children are active outdoors.
Because physical activity leads to increased ventilation, the ability to identify specific locations of activity especially near sources of high pollution can improve risk assessment for lung function impairment. Our findings of a positive association between outdoor active time in warmer weather months and both elevated NO2 exposure and reduced lung function demonstrate a need to inform individuals in urban communities about location specific exposure risks. Our findings also support the need for continued attention towards improving air quality especially in urban communities.