The exposure of disadvantaged populations in freeway air-pollution sheds: a case study of the Seattle and Portland regions

Abstract

Freeway-related air pollution and its harmful health risks have been observed in recent research in the environmental-health sciences. In this study we investigate the impact of freeway and arterial-road air pollution on vulnerable populations—for example, the poor, minorities, children, and the elderly—whose housing options are limited. Because many mobile-source emissions decay rapidly with distance, approaching background concentrations at 330 ft from the freeway, populations living near limited access roads are most at risk from exposure. Furthermore, microscale air monitoring systems are rarely in place at these locations in the United States. In this research we will define freeway air-pollution sheds with the aid of a geographic information system analysis and determine populations that may be at risk from exposure to mobile-source pollutants in two West Coast metropolitan areas (Seattle and Portland). We then use cluster analysis to identify key neighborhoods at risk in Seattle. Subsequently, we apply a hedonic pricing model to understand the extent to which house price values in Seattle are related to freeway proximity. Finally, we discuss policy options, planning implications, and mitigation measures, including an assessment of air-quality monitoring needs and land-use prescriptions.

Spatial planning procedures and property prices: The role of expectations

“…There is a growing body of evidence indicating that those who live in close proximity to a highway are at increased risk of suffering from serious health effects (Bae et al, 2007). Noise is another nuisance to those living close to highways .…”

Valuing Environmental Quality: A Space-Based Strategy*

“…This specification is very similar, though not identical to, a specification developed independently by Bae et al (2007) for a hedonic analysis also focused on the central Puget Sound region.…”

The application of three methods to measure the statistical association between different social groups and the concentration of air pollutants in Montreal: A case of environmental equity

“…First among these is proximity to sources that generate air pollutants, an approach that has often involved defining "buffer zones" ranging from 0 to 300 metres (m) around major roads (Amram et al, 2011;Bae et al, 2007;Cesaroni et al, 2010;Chakraborty, 2006;Chakraborty et al, 1999;Green et al, 2004;Gunier et al, 2003;Houston et al, 2006;Jacobson et al, 2005) or creating density indices based on road network hierarchy (Houston et al, 2004). To evaluate environmental equity, logistic regression is often modelled with a binary dependent variable indicating whether a census tract or city block is located at least n metres from a section of highway (200 m, for example), and with independent variables describing the proportions of targeted groups (e.g., ethnic minorities) within buffers of various radii.…”