"It may be short-lived, but we expect at least a couple days of cleaner air coming up", a multiagency update said.
Sunday's weather sees the continuation of the a special air quality statement for Metro Vancouver.
Smoke from Canadian wildfires are drifting towards the Inland Northwest.
That's Dr. Coralynn Sack, a pulmonologist and specialist in environmental health at the University of Washington, who notes that with an air quality index above 100 - it's mostly sensitive populations at risk.
"You probably want to reduce the level of exercise you're doing outside", Dr. Sack said.
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The limited visibility has also created delays at Seattle-Tacoma Airport, according to the Federal Aviation Administration, with greater aircraft separation in place.
It's a rare occurrence that also happened a year ago, raising concerns for many locals that it may become normal during wildfire season. "We now have an air quality reading of "Very Unhealthy/Purple". Those with heart disease may experience chest pain, irregular heartbeats, shortness of breath and fatigue.
According to Environment Canada, local smoke levels will vary depending on wind direction and fire characteristics, but improvement is not expected until the weather changes significantly across the province.
The Department of Ecology has advised that children, the elderly and those with respiratory illnesses stay indoors, or limit outside activity in areas classified as hazardous.
In Portland, six tourists from Lincoln, Nebraska, posed for a photo in front of the Willamette River with the usual Mount Hood backdrop shrouded in haze.
Dr. Sack says that ultimately, short-term exposure shouldn't worry most of us - our lungs typically expel the type of particles now smothering the Sound.