10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Exploring the Socio-Economic Inequalities in the Exposure to Air Pollutants during Commuting by Different Travel Modes
IOAR RIVAS, Prashant Kumar, Alex Hagen-Zanker, University of Surrey
Abstract Number: 1491 Working Group: Aerosol Exposure
Abstract Commuters usually remain in close proximity to the main source of air pollution in urban areas: road traffic emissions (Dons et al., 2011). These emissions from combustion processes, mainly in a particulate form, are suspected to be particularly harmful (WHO, 2013). Previous studies suggest inequalities in exposure, with people residing in the most deprived areas generally experiencing higher concentrations of air pollutants (Fecht et al., 2015). The objective of this work is to determine differences between transport mode in the exposure during commuting to different fractions of Particulate Matter (PM), Black Carbon (BC) and ultrafine particle number concentrations (PNC) in London. Moreover, we investigated the determinants of the concentrations through linear regression models, as well as the presence of possible inequalities related to income deprivation. We monitored the previously mentioned pollutants in typical commutes from four London areas with different levels of income deprivation (G1 to G4, from most to least deprived) by car, underground and bus (the most popular transport modes) at three different times of the day (morning peak, afternoon off-peak and evening peak). The highest BC and PM concentrations were found in the G1 route while the highest PNC was observed in G3. G2 showed the lowest concentrations of all pollutants. We did not observe a direct relationship between income deprivation and pollutant concentrations, suggesting that differences between transport modes were more important. The underground showed the highest PM concentrations, followed by buses and, with much lower concentrations, cars. BC concentrations were also higher in buses than cars due to a higher infiltration of outside pollutants into bus. BC could not be measured in the underground due to interferences with iron in the measuring system. PNCs were highest in buses, closely followed by cars and lowest in underground due to the absence of combustion sources. Regression models indicated that the variation in the concentrations for each transport mode was mainly explained by wind speed or ambient concentrations (evaluated in separate models) and, to a lower degree, by route and period of the day. In multivariate models, wind speed was the common significant predictor for all pollutants in car and bus; and the only significant predictor for the different PM fractions. For the underground, wind speed was not a determinant. However, line and type of windows on the train explained 42% of the variation of PNC and 90% of all PM fractions. Statistics from Census data revealed that people from less deprived areas have a predominant use of car, and therefore receive the lowest doses (Respiratory Deposition Dose, RDD <1 µg·h-1) during commute while producing the largest emissions per commuter. Conversely, commuters residing at higher income deprivation areas have a major dependence on the bus, receiving higher exposures (RDD between 1.52-3.49 µg·h-1) while generating less emissions per person. This situation falls within the core principle of environmental justice as reviewed by Brulle and Pellow (2006). Therefore, there is a need to include the socioeconomic dimension in exposure assessment to account for the environmental injustice that may affect the exposure levels.
This work is carried out within the ASTRID project, funded by ESRC-NWO-FAPESP (ES/N011481/1).
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