Abstract Number: 230 Working Group: Carbonaceous Aerosol
Abstract The road transportation sector contributes largely to air pollution in urban areas, and accurate knowledge of vehicle emission factors (EF) is crucial to prepare reliable emission inventories which, in turn, are strategic tools for air quality management. Curbside and rooftop concentrations of several traffic-related species were measured within a busy street canyon in Londrina (Brazil) and EF for NOx, black carbon (BC), fine particles (PM2.5) and particle number (N) were calculated based on these measurements and inverse modeling using the Operational Street Pollution Model (OSPM). We highlight the importance of this work in quantifying the effects of possible off-cycle BC, PM2.5, NOx and N emissions in urban areas by measuring emissions in real driving conditions in a continent-sized country where there is a lack of EF studies. On average, one heavy-duty vehicle (HDV) emitted more pollutants than one light-duty vehicle (LDV) with EFHDV/EFLDV ratios of 27, 12, 10 and 4 for BC, NOx, PM2.5 and N, respectively. Our results are consistent with literature values reported by other studies conducted also under real-world driving conditions in Brazil (São Paulo city). As far as we know, we report the first EFN ever measured in Brazil and when compared to other works carried out in street canyons in Europe, they were similar for the HDV fleet but much higher for the LDV fleet. Our EF are much higher than laboratory measurements conducted in Brazil and Europe, especially for particles. This finding suggests that the EF derived from laboratory tests should be revised for all vehicle categories in Brazil, since they are used to compile official national inventories for the road transportation sector and also to assess their associated health and climate (in the case of BC) impacts. Finally, Brazilian regulators should incorporate certification procedures that more closely resemble real-world conditions. For example, adopting certification tests in laboratory that consider cold-start and low-speed driving and also real drive emission (RDE) testing already in place in the European Union. There is also a need of quantifying the non-exhaust EF for particulate matter and determine mileage deterioration for all pollutants and vehicle categories, which are missing in all official inventory calculations.