Impacts of Multi-Modal Commuting on Personal Air and Noise Exposures and Airway Inflammation

Abstract

Background: Modern mobility can include mixtures of transportation options, which potentially impact pollution exposures and health.Objectives: To investigate variations in traffic-related air and noise pollution exposures and cardiorespiratory effects in different microenvironments in Chengdu, China.Methods: Three sections of a city were chosen as locations for a scripted exposure study: the urban core, a developing neighborhood, and a suburb. Exposures for four commuting modes (car, bus, subway, and shared bike) with overlapping routes were measured using portable instruments (measuring PM2.5, Black Carbon, and noise) in summer and winter (5 repeats in each season). We assessed the feasibility of collecting health measures (ECG, breathing rate, respiratory minute ventilation, fractional exhaled nitric oxide, and spirometry measurements) in winter for four healthy, non-smoking young adults. Health measures on commute days were compared to a control measurement collected two days after the last commute.Results: Air pollutant measures showed large seasonal variance, with winter medians more than three times higher than those in summer (PM2.5: 33 vs 123 ug/m3, BC: 2395 vs 9125 ng/m3). The highest PM2.5 and BC levels were measured in the urban core (both p<0.0001). Noise tended to be higher in the summer, and was higher in the suburb than other neighborhoods (p<0.0001). In summer, riding the subway had the highest pollution levels, while riding a car was found to be the least polluted mode (p<0.0001). In winter, the highest air pollution levels were found for shared bike use (p<0.0001); subway and bus trips had the lowest PM2.5 and BC level respectively (p<0.0001). Preliminary linear mixed modeling suggested that riding a car may be associated with increased airway inflammation (p=0.004).Conclusion: Results from this study suggest that mode, location and season of transportation impact personal traffic-related pollution exposure and airway inflammation.