Click on this link Auto Body Rule Tool - Local Hazardous Waste Management Program in King County
, then click on the paint booth, then click on the yellow marker on the intake stack. It states filters containing HOC's are hazardous waste. Then Click on the Filters heading for more info.
It appears that Spokane County is following King County's lead in this area of discussion.
Spokane Regional Clean Air Agency - Industry - Surface Coaters