A multi–pollutant, risk–based approach to air quality management: Case study for Detroit

In response to the need to further explore and understand the technical needs and challenges presented by implementing a multi–pollutant, risk–based approach to air quality management, a case study was performed for the urban area of Detroit. As part of this case study, two contrasting air quality control strategies were assessed and compared. One strategy mimicked the “status quo”, where controls were selected separately to address ozone (O3) and fine particulate matter (PM2.5) nonattainment at monitor locations, while the other strategy reflected a “multi– pollutant, risk–based” approach aimed at further reducing population risk from exposure to ozone, PM2.5 and selected air toxics while still addressing ozone and PM2.5 nonattainment. This paper describes the technical framework used to apply and evaluate the two contrasting air quality control strategies and describes the relative benefits of each. Based on this case study, we found that the “multi–pollutant, risk–based” approach was able to: (1) achieve the same or greater reductions of PM2.5 and O3 at monitors; (2) improve air quality regionally and across the Detroit urban core for multiple pollutants; (3) produce approximately two times greater monetized benefits for PM2.5 and O3; (4) reduce non–cancer risk; and (5) result in greater net benefits and be more cost effective.