PSCAA 2003 - "Final Report: Puget Sound Air Toxics Evaluation"

Keill, Leslie; Maykut, Naydene
"Final Report: Puget Sound Air Toxics Evaluation"
Puget Sound Clean Air Agency and Washington State Department of Ecology
October 2003
On the Web
Relevance: high

In this preliminary study, PSCAA measured and modeled exposure to outdoor air toxics in 6 locations around western King County, including Beacon Hill, Lake Sammamish, and Seatac. They estimated cancer risk using several methods, including one that takes into account commuting. They also seem to suggest that it may not matter much what macroenvironment you live in (i.e., Beacon Hill vs. Lake Sammammish): "Concentrations, and corresponding risks, were relatively consistent among areas measured and modeled throughout the Puget Sound region. Although some differences were apparent, overall it is clear that the sites and the region as a whole have similar emission sources of concern (e.g., diesel particulate matter, mobile-source-related VOCs, and probably woodsmoke)." Smaller geographical scale factors (busy road, factory, cleaning products) are not accounted for.

Cancer risks from the toxics other than diesel and woodsmoke range from 57 in a million (Lake Sammamish) to 100 in a million (Georgetown)

Other key points from the study:

• "Mobile sources are likely to account for approximately 85% to 95 % of the potential cancer risks among outdoor sources"
• "The majority of cancer risk estimated ... is due to diesel soot." (78%)
  • But they appear to have measured diesel only at Beacon Hill
• The study does not evaluate indoor sources, and while in one model it accounts for commuting, I'm not sure if it accounts for different commutes from different locations.
• Table for chemical cancer and non-cancer risks

Questions:

• Q: In what manner did they account for commuting?
• Q: Did they measure diesel soot any place other than Beacon Hill? Do they know how it varies around the Sound?
  • A: So they do not directly measure for diesel particulate matter or for woodsmoke, but they do have estimated source apportionment and use an aethelometer to measure black carbon in 5 places including Lake Forest Park, Beacon Hill, and Duwamish.