Scope Study for Expanding the Great Lakes Toxic Emission Regional Inventory to include Estimated Emissions from Mobile Sources

Introduction

The eight Great Lakes states and Ontario province working together through the Great Lakes Commission are currently in the process of developing a regional emission inventory for airborne toxic pollutants. This regional emission inventory is focused on 49 toxic air pollutants which have been identified as significant contributors to the contamination of the Great Lakes. The development of the regional emission inventory has included the development of technical specifications for a regional air toxic database (Phase I); the development of an automated Regional Air Pollutant Inventory Development System (RAPIDS), an emission factor database, and an emission inventory protocol for inventorying hazardous air pollutants (Phase II); and the full implementation of the protocol and emission inventory software to complete an eight state point and area source toxic air emission inventory (Phase III). To date, this inventory system has been developed to estimate emissions from point and area sources only.

The contribution of the automobile to air pollution has been recognized since the 1950s. Emissions from motor vehicles have been estimated to contribute 61 percent of the cancer risk from pollutants that are released into the air by various sources in the Twin Cites metropolitan area. Deposition of airborne toxic contaminants to the Great Lakes increases burden of toxic chemicals in the food chain. Therefore, the compilation of data on toxic emissions from mobile sources as well as from point and area sources in the Great Lakes states is a key component of any strategy to reduce toxic loading to the lakes.

The Great Lakes regional emission inventory started Phase IV in October 1995 to expand the inventory to include emissions from mobile sources. The first step in Phase IV was to conduct a scope study that first clarified the significance of toxic air emissions that are emitted from mobile sources to the Great Lakes. This scope study then identified the toxic air pollutants that are emitted by mobile sources and are significant contributors to the contamination of the Great Lakes. The study also determined the level of detail needed in the estimation of the mobile source emissions. Research was also conducted in the scope study to develop the emission estimation methodologies for the toxic compounds of concern from mobile sources. Finally, this study outlined tasks for software development.

Under the guidance of this scope study, software will be developed to estimate the emissions of targeted toxic compounds from mobile sources. These emissions can then be aggregated with emission estimates from point and area sources to provide a more comprehensive estimate of toxic air emissions in the region.