Evaluation of Bicyclists Exposure to Traffic-Related Air Pollution along Distinct Facility Types

While bicyclists and other active travelers obtain health benefits from increased physical activity, they also risk an uptake of traffic-related air pollution. But pollution exposure for urban bicyclists is not well understood due to a lack of direct measurements and insufficient analysis of the determinants of exposure. This knowledge gap impedes pollution-conscious transportation planning, design, and health impact assessment. The research presented in this report generates new connections between transportation system characteristics and pollution exposure for bicyclists. The primary research questions are: 1) How does urban bicyclists’ exposure to air pollution vary with roadway and travel characteristics? and 2) To what extent can transportation-related strategies reduce exposure? Novel methods to collect and integrate bicycle, rider, traffic, and environmental data are also introduced. Bicyclist exposure concentrations and travel characteristics were collected on a wide range of facilities in Portland, Oregon. High-resolution trajectory and pollution data were then integrated with roadway and traffic data. Models of exposure were estimated from the on-road data. Important new quantifications in the models include the effects of facility type, average daily traffic (ADT), stop-and-go conditions, and industrial corridors on multi-pollutant exposure. Findings from this research and the literature are distilled so that they can be incorporated into bicycle network design guidelines.