Black carbon reduces the beneficial effect of physical activity on lung function

Introduction: When physical activity is promoted in urban outdoor settings (e.g., walking and cycling), individuals are also exposed to air pollution. It has been reported that short-term lung function increases as a response to physical activity, but this beneficial effect is hampered when elevated air pollution concentrations are observed. Our study assessed the long-term impact of air pollution on the pulmonary health benefit of physical activity. Methods: Wearable sensors were used to monitor physical activity levels (SenseWear) and exposure to black carbon (microAeth) of 115 healthy adults during 1 wk in three European cities (Antwerp, Barcelona, London). The experiment was repeated in three different seasons to approximate long-term behavior. Spirometry tests were performed at the beginning and end of each measurement week. All results were averaged on a participant level as a proxy for long-term lung function. Mixed effect regression models were used to analyze the long-term impact of physical activity, black carbon and their interaction on lung function parameters, forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), FEV1/FVC, forced expiratory flow (FEF)25–75, and peak expiratory flow. Interaction plots were used to interpret the significant interaction effects. Results: Negative interaction effects of physical activity and black carbon exposure on FEV1 (P = 0.07), FEV1/FVC (P = 0.03), and FEF25–75 (P = 0.03) were observed. For black carbon concentrations up to approximately 1 µg·m-3, an additional MET·h-1·wk-1 resulted in a trend toward lung function increases (FEV1, FEV1/FVC, and FEF25–75 increased 5.6 mL, 0.1% and 14.5 mL·s-1, respectively). Conclusions: We found that lung function improved with physical activity at low black carbon levels. This beneficial effect decreased in higher air pollution concentrations. Our results suggest a greater need to reduce air pollution exposures during physical activity.