Should traffic-related air pollution and noise be considered when designing urban bicycle networks?

This study was motivated by an interest in capturing the factors affecting the exposure of cyclists to ambient Ultrafine Particles (UFP), Black Carbon (BC), and noise (LA_eq) across the entire bicycle network of the City of Toronto. Measurements were conducted along 270 km of unique roads, and we developed land use regression models and exposure surfaces. Median UFP, BC and noise levels recorded were 19,848 part/cm³, 1224 ng/m³, and 72.9 dB respectively. The average UFP and BC exposures along the biking routes (18,900 part/cm³ and 1130 ng/m³) were higher than the average levels measured at a fixed station located in downtown Toronto (13,300 part/cm³ and 809 ng/m³). The highest UFP and BC levels were experienced on dedicated bicycle tracks (30,000 part/cm³ and 1600 ng/m³ as median concentrations), while the highest noise levels occurred on major roads (median of 74 dB). In contrast, median levels on trails were 13,200 part/cm³, 535 ng/m³ and 70.2 dB, for UFP, BC, and noise. The exposure surfaces developed for the air pollutants and noise were intersected with the planned extensions to the bicycle network in the City of Toronto to evaluate the distributions of exposures expected across the future cycling network. We observe that the mean and median UFP, BC, and noise levels across planned facilities are equal to or significantly higher than the levels across the current network.