"Smoke is severely impacting air quality today", the Spokane Regional Clean Air Agency said in a tweet Sunday morning.
The poor air quality has also been affecting air travel in the province's interior.
"The millions of vehicles on Bay Area roads during these hot summer months create unhealthy air quality and make breathing more hard for many", said Jack Broadbent, executive officer of the air district.
"Thursday and Friday look a lot fresher as a westerly flow kicks in and steers the smoke to the east", he said.
Over the last week, all three Prairie provinces have been under special air quality statements for high smoke concentrations.
The National Weather Service has issued air quality alerts for much of Washington state.
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The smoke is expected to move south on Monday and persist through the night.
A new mobile app from The Oregon Department of Environmental Quality allows you to have information about your area's air quality conditions at your fingertips.
"Local smoke levels may vary based on wind direction and fire characteristics but, until a significant change in the provincial weather pattern occurs, widespread air quality improvements are not expected".
About 2,200 evacuees have ended up in Prince George, where some people said they were sleeping in their vehicles until other shelter could be found.
The north end of Vancouver Island is covered by the advisory as well.