![]() ![]() ![]() Complicating the issue, walking and cycling take longer and increase individuals’ breathing rates, potentially exposing active commuters to higher inhaled doses of PM 2.5 compared to automobile or public transit. ![]() Some studies show higher PM 2.5 exposures for cyclists and walkers compared with automobile commuters, whereas others report no difference or lower exposures for active commuters compared to those using automobiles or public transit. However, to date there are relatively few studies on PM 2.5 exposures by type of commuting in the United States. One strategy to reduce daily PM 2.5 exposure is to encourage a shift in modal transportation toward increased use of public transit and active commuting (walking and cycling). American commuters spend approximately 26 minutes commuting one direction to work each day, making long-term and acute health effects from exposure a concern. Thus, for commuters, traffic-related air pollution can significantly contribute to daily PM 2.5 exposures, especially on arterial roads during high-traffic “rush hour” time windows. There is extensive spatial and temporal variation in intra-urban air pollution exposures, with PM 2.5 often occurring at higher concentrations near major roadways due to gasoline and diesel engine exhaust. In urban areas, motor vehicle exhaust contributes significantly to PM 2.5 air pollution. Our findings also support previous studies showing that driving with windows closed is protective against traffic-related PM 2.5 exposure.Įxposure to fine particulate matter (PM 2.5) in ambient air is associated with multiple adverse health outcomes in adults and children. Our findings support previous studies showing that active commuters receive a greater PM 2.5 dose and have higher rates of exposure than commuters using automobiles or public transportation. Similarly, the exposure rates were highest for cycling (18.0 μg/hr) and walking (16.8 μg/hr), and lowest for driving with windows closed (3.7 μg/hr). The estimated inhaled doses over the 2.7 km route were 6.83 μg for walking, 2.78 μg for cycling, 1.28 μg for light-rail train, 1.24 μg for driving with windows open, 1.23 μg for bus, and 0.32 μg for driving with windows closed. Mean PM 2.5 concentrations ranged from 5.20 μg/m 3 for driving with windows closed to 15.21 μg/m 3 for driving with windows open. Using previously published minute ventilation rates, we estimated the inhaled dose and exposure rate for each mode of commuting. In this study, we examined breathing zone PM 2.5 exposures for six different modes of commuting (bicycle, walking, driving with windows open and closed, bus, and light-rail train) simultaneously on a single 2.7 km (1.68 mile) arterial urban route in Salt Lake City, Utah (USA) during peak “rush hour” times. To date, studies show conflicting results for PM 2.5 exposures based on mode of commuting, and few studies compare multiple modes of transportation simultaneously along a common route, making inter-modal comparisons difficult. Traffic-related air pollution in urban areas contributes significantly to commuters’ daily PM 2.5 exposures, but varies widely depending on mode of commuting. ![]()
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