Summary of Results of the Duwamish Valley Regional Modeling and Health Risk Assessment, Seattle, Washington

Gary Palcisko (1), Elmer Diaz (2), Lenford O'Garro (2)

(1) Washington State Department of Ecology, Washington (2) Washington State Department of Health, Washington

     Abstract Number: 176
     Last modified: November 7, 2009

Abstract
The Duwamish Valley is an industrialized area in south Seattle. Residents from two communities in the area, Georgetown and South Park, asked the Washington State Department of Health (DOH) to conduct an assessment of the impacts that air pollution may have on their health. The objectives of this study were to identify which air pollutants are key contributors to acute and/or chronic health risk, what sources are the key contributors to acute and/or chronic health risk, and to what degree are different geographic areas of south Seattle impacted by air emissions in the Duwamish Valley. The Air Toxics Hotspots Analysis and Reporting Program (HARP) developed by California Environmental Protection Agency (EPA) was the primary tool used to model air emissions from multiple sources (e.g., stationary and mobile emissions) in south Seattle. Air emission sources in the Duwamish Valley include point, mobile and wood stove sources. The dispersion and ground level impact of these emissions were then modeled using local meteorological and terrain conditions. Non-cancer hazards and cancer risks were calculated based on modeled ground level pollutant concentrations at many locations throughout the project area. Modeling results indicated diesel soot and wood smoke are the main contaminants that raise the pollution levels in the area and increase potential health risks for residents. Diesel soot presents the biggest health threat. Potential health risks are higher for people who live near major pollution sources. This study reaffirms findings of an earlier Puget Sound air toxic evaluation conducted in Seattle by the Puget Sound Clean Air Agency in 2003, and is consistence with National Air Toxics (NATA), Portland Air Toxics Assessment (PATA), South Coast, California Air Toxics Resources Board (CARB), and Vancouver Metro.