Inhalation of air pollution during transport is an important exposure pathway, especially for certain modes of travel and types of particles. We measured concentrations of particulate air pollution (particle number [PN], black carbon [BC], fine particles [PM2.5], particle size) using a mobile, bicycle-based monitoring platform during morning and afternoon rush-hour to explore patterns of exposure while cycling (34 days between August 14 and October 16, 2012 in Minneapolis, MN). Measurements were geo-located at 1 s intervals along 3 prescribed monitoring routes totaling 85 h (1426 km) of monitoring. Mean morning [afternoon] on-road concentrations were 32,500 [16,600] pt cm-3, 2.5 [0.7] μg m-3 BC, 8.7 [8.3] μg m-3 PM2.5, and 42  nm particle diameter. Concentrations were correlated with street functional class and declined within small distances from a major road (e.g., for PN and BC, mean concentration decreased ~20% by moving 1 block away from major roads to adjacent local roads). We estimate the share of on-bicycle exposure attributable to near-traffic emissions (vs. regional pollution) is ~50% for PN and BC; ~25% for PM2.5. Regression models of instantaneous traffic volumes, derived from on-bicycle video recordings of nearby traffic, quantify the increase in particle-concentrations associated with each passing vehicle; for example, trucks were associated with acute, high concentration exposure events (average concentration-increase per truck: 31,000 pt cm-3, 1.0 μg m-3 PM2.5, 1.6 μg m-3 BC). Our findings could be used to inform design of low-exposure bicycle networks in urban areas.
- Active travel
- Non-motorized travel
- Traffic mix
- Traffic-related air pollution