10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Fine Paritculate and Black Carbon Exposure for Users of a Bus Rapid Transit System: Role of Vehicle Age and Impact of Fleet Renewal
RICARDO MORALES BETANCOURT, Boris Galvis, Juan Manuel Rincón, Maria Alejandra Rincón, Yadert Contreras Barbosa, Universidad de los Andes
Abstract Number: 1021 Working Group: Aerosol Exposure
Abstract This research documents the extremely high exposure concentration to fine aerosol particles (PM2.5), black carbon (BC), and carbon monoxide, CO, experienced by users of one of the world largest Bus Rapid Transit (BRT) systems, located in Bogota, Colombia. Extensive sampling of the system was performed over a span of 12 months covering all branches of the system and a significant fraction of the system stations. Sampling of PM, BC, and CO was performed on-line using portable devices at a 10 second resolution. The particle size distribution was determined using an optical particle sizer. Gravimetric samples were collected to determine average trip concentration. Physical activity was determined in real time using portable accelerometers. Average ratio of in-bus to background concentration was 9:1 for PM2.5 and 5:1 for CO. Nearly 50% of in-bus fine particulate mass was found to be BC, suggesting most of the particulate pollution in the system comes from diesel combustion. In-bus exposure level is shown to be strongly correlated with vehicle emission standard and vehicle kilometers traveled. The contribution of a typical round trip in the BRT system was estimated to account for 60% of PM2.5 daily dose, and between 75% to 85% of BC daily dose. Exposure levels where twice as large for passengers inside BRT buses with Euro II and III emission standard compared to those in Euro IV or V vehicles. The significantly lower exposure to PM2.5, BC, and CO observed for commuters in bus models with stricter emissions standards suggests that a renewal of the older portion of the fleet could have a disproportionately large effect on reducing population exposure to air pollutants. This large benefit is shown to be only possible in cities with moderate air pollution levels and a marked gradient of in-bus to background pollution levels. The results of our observations are likely to be relevant to many cities given the rapidly growing number of BRT systems being implemented in large urban centers around the globe.