Student commute mode and route choice are important in determining commute safety as well asinfluencing student health, as recognized by the Safe Routes to School program. Little has been done,however, to examine the air pollution exposure impacts of student mode choice as students movethroughout the roadway environment. This study examines differences in air pollutant exposure alongthree different routes for students commuting to school via auto, transit bus, and walking. Three pollutanttypes are included: PM2.5, ultrafine particles, and carbon monoxide. The route recommended by SafeRoutes to School is inconsistently observed to have the lowest pollutant concentrations. Results indicatetraveling along lower-volume roadways reduces walking exposure, while traveling along busier roadwaysresults in exposure to greater pollutant concentrations. Walking exposure is found to be greater thandriving exposure, but less than bus exposure. The maximum concentration for each pollutant was locatedalong the most congested roadway. Pollutant concentrations for the walking mode are mapped to givevisual representation of exposure fluctuations during a commute. This research reinforces the importanceof selecting low-volume roadways for safety, but also to minimize exposure, and demonstrates a need forfurther research examining the factors that determine exposure along different street types ranging fromarterial to neighborhood roadways. These results serve as a link to existing environmental justice airquality research between exposure at the home and exposure at the school in urban areas.
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