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We report on commuters' exposure to black carbon (BC), PM 2.5 and particle number (PN, with aerodynamic diameter, d a , in the range 0.01 −3 and 3.9 ± 26.0 μg m−3 on diesel- and biodiesel-fuelled buses, respectively. Mean PM 2.5 concentrations were similar (31.6 ± 28.5 μg m−3 and 29.0 ± 17.8 μg m−3), whilst mean PN concentrations were larger on the biodiesel buses (56,697 ± 26,800 # cm−3 vs. 43,322 ± 32,243 # cm−3). The results are in line with studies on biodiesel emission factors that reported lower BC mass but more particles with smaller diameters. Our hypothesis is that different emission factors of diesel and biodiesel engines reflected in differences of in-cabin particulate concentrations. We found that the passenger exposure during the bus commutes was affected not only by the fuel used but also by the street geometry along the route, with segments with canyon configurations resulting in peak exposure to particulates. The results suggest that i) switching from diesel to biodiesel may help abate commuters' exposure to BC particles on-board buses of the BRT system, whilst it would need to be complemented with after-treatment technologies to reduce emissions; ii) further reductions in exposure (to peaks in particular) could be achieved by changing bus routes to ones that avoid passing through narrow urban street canyons. Image 1 • In-cabin PM concentrations were linked to type of fuel and street geometry. • Mean black carbon concentration was lower on biodiesel than on diesel buses. • Mean particle number concentration was higher on biodiesel than on diesel buses. • Mean in-cabin PM 2.5 concentration showed no statistically significant differences. • Peak in-cabin PM concentrations persisted in canyons regardless of the fuel used. [ABSTRACT FROM AUTHOR]

The open burning of municipal solid waste (MSW) –frequently observed in developing countries– emits harmful pollutants, including fine particulate matter (PM 2.5) and black carbon (BC), and deteriorates the air quality in urban areas. This work reports on PM 2.5 and BC measurements (fixed and mobile) conducted in a residential neighborhood on the outskirts of a Brazilian city (Londrina), complemented by a public opinion survey to understand the open burning in the context of waste management. Mean (± standard deviation) BC concentration (1.48 ± 1.40 μg m−3) at the fixed sites of the neighborhood was lower than downtown, while PM 2.5 (9.68 ± 8.40 μg m−3) concentration was higher. The mobile monitoring showed higher mean PM 2.5 concentrations but lower BC/PM 2.5 ratios than downtown, with sharp and fast spikes (up to 317.87 and 565.21 μg m−3 for BC and PM 2.5, respectively). The large spatial heterogeneity of particulate concentrations was associated with the occurrence of MSW burning events. Our observations were verified by the survey respondents who identified poor waste management practices: garbage in streets, waste burning, and illegal dump sites. Even though the area has a municipal waste collection service, the majority of the respondents (87%) had seen waste burning close to their homes on a weekly basis, and think that people burn waste out of habit (54%) and because they are not patient to wait for the collection services (67%). To combat this illegal practice, we suggest raising the public awareness through campaigns at local level, adopting education initiatives and economic incentives for correct waste segregation, and enforcing regular inspection of burning events by the authorities. Our research method proved to be a time- and cost-effective approach for mapping particulate concentrations and for identifying undesirable waste practices, and could be effectively applied to other global cities. Unlabelled Image • Open waste burning raises BC and PM 2.5 concentrations at the neighborhood level. • PM 2.5 concentrations reach values higher than in heavily trafficked roads. • Combined mobile and fixed-site monitoring unveiled air quality features at fine-scale resolution. • A public opinion survey indicated that open waste burning occurs frequently in the area. • Most people do not sort their waste properly, but dump and burn them in vacant lots. [ABSTRACT FROM AUTHOR]