Air pollutant exposure and inhaled dose during urban commuting: a comparison between cycling and motorized modes

Active commuting has great health, environment, economic, and social benefits. However, cyclists are at risk for exposure to vehicle-related air pollutants due to their proximity to vehicle traffic and elevated respiratory rates. Consequently, more information on differences in inhaled doses between different transport modes is needed. The aim of this study is to assess and map the exposure of travelers to air pollutants using different transportation modes and to consider minute ventilation variablity and travel duration for the calculation of inhaled dose. Particulate matter (PM10, PM4, PM2.5 and PM1), CO, volatile organic compound (VOC), CO₂, and O₃ were measured between December 2013 and March 2014 in a total of 75 travels performed by bus, metro, car, bicycle, and motorcycle at five periods of the day (8, 11, 14, 17:30, and 21 h). Results showed that car drivers and bus passengers in urban streets may be exposed to higher pollutant levels than cyclists traveling in the same streets. However, this enhanced air pollution exposure is compensated by the higher ventilation rates of cyclists, which presented the highest inhaled doses. To reduce exposure concentrations, spatial and temporal separation of cyclists from motorized vehicle traffic should be achieved with separated bicycle facilities, low volume routes, and off-peak travel.