Exposure to fine particulate, black carbon, and particle number concentration in transportation microenvironments: Fid-Bau Portal

Exposure to fine particulate, black carbon, and particle number concentration in transportation microenvironments

Morales Betancourt, R. / Galvis, B. / Balachandran, S. / Ramos-Bonilla, J.P. / Sarmiento, O.L. / Gallo-Murcia, S.M. / Contreras, Y.

Abstract

AbstractThis research determined intake dose of fine particulate matter (PM2.5), equivalent black carbon ( $e BC$ ), and number of sub-micron particles ( $N_{p}$ ) for commuters in Bogotá, Colombia. Doses were estimated through measurements of exposure concentration, a surrogate of physical activity, as well as travel times and speeds. Impacts of travel mode, traffic load, and street configuration on dose and exposure were explored. Three road segments were selected because of their different traffic loads and composition, and dissimilar street configuration. The transport modes considered include active modes (walking and cycling) and motorized modes (bus, car, taxi, and motorcycle). Measurements were performed simultaneously in the available modes at each road segment. High average $e BC$ concentrations were observed throughout the campaign, ranging from 20 to 120 $μ g m^{- 3}$ . Commuters in motorized modes experienced significantly higher exposure concentrations than pedestrians and bicyclists. The highest average concentrations of PM2.5, $e BC$ , and $N_{p}$ were measured inside the city's Bus Rapid Transit (BRT) system vehicles. Pedestrians and bicycle users in an open street configuration were exposed to the lowest average concentrations of PM2.5 and $e BC$ , six times lower than those experienced by commuters using the BRT in the same street segment. Pedestrians experienced the highest particulate matter intake dose in the road segments studied, despite being exposed to lower concentrations than commuters in motorized modes. Average potential dose of PM2.5 and $e BC$ per unit length traveled were nearly three times higher for pedestrians in a street canyon configuration compared to commuters in public transport. Slower travel speed and elevated inhalation rates dominate PM dose for pedestrians. The presence of dedicated bike lanes on sidewalks has a significant impact on reducing the exposure concentration for bicyclists compared to those riding in mixed traffic lanes. This study proposes a simple method to perform loading effect correction for measurements of black carbon using multiple portable aethalometers.

Highlights•Dose of commuters to PM2.5, black carbon, and ultrafine particles was measured.•Exposures were 6 times higher in public buses than for pedestrians, and 10 times background level.•Street geometry had great impact on exposure with twice as large PM pollution in street canyons.•Presence of dedicated bike lanes was shown to reduce exposure of cyclists to PM pollution.•Car passengers were exposed to the lowest inhaled dose.