Smog and Socio-economics: an Evaluation of Equity in Traffic- Related Air Pollution Generation and Exposure

How traffic-related air pollution generation and exposure is distributed among different population groups is an important environmental justice concern. From a social equity perspective, many questions arise at the metropolitan scale: Do socially disadvantaged communities have higher exposure levels to traffic-related air pollution? Do discrepancies exist wherein neighborhoods are not exposed to similar levels of pollution than they themselves generate? And, is there a relationship between this discrepancy and social disadvantage? These questions are examined for the Montreal metropolitan region through the development of an integrated transport and emission model. Two measures of traffic-related air pollution are estimated at the traffic analysis zone level: (1) generation (average emissions per household), and (2) exposure (average residential zone concentration). A social disadvantage index is also calculated that incorporates elements of social and material deprivation. Three levels of inequity exist regarding emissions, exposure and socioeconomics. Firstly, social disadvantage was found to have a positive relationship with exposure, meaning that the most socially disadvantaged communities tend to experience the highest levels of traffic-related air pollution. Spatial discrepancies in emission generation versus exposure are also present for most of the metropolitan region. Furthermore, the communities that face a double-burden of greater disadvantage and higher exposure also tend to create the lowest quantities of pollution.