The skies began to clear Monday, allowing residents and visitors to begin to breathe easy again after a plume of smoke from several large wildfires in Canada drifted across the Strait of Juan de Fuca and spread over the North Olympic Peninsula.
But that could change Tuesday.
Wind patterns that helped clear the smoke on Monday may reverse as the wind shifts again, said Allen Kam, meteorologist for the National Weather Service in Seattle.
Kam said the severity of Tuesday’s possible smoke inundation depends on how actively the Canadian fires burn.
On Sunday, heavy smoke choked off the sun and created a dark orange-hued afternoon sky that reduced Peninsula air quality from its normal “good” rating to “unhealthy” in many areas — and even to “unhealthy” in the Neah Bay area, according to the Olympic Region Clean Air Agency’s air quality monitoring stations.
Air quality on the Peninsula usually registers well into the “good” category on the air quality advisory scale of the Olympic Region Clean Air Agency (ORCAA), said Odelle Hadley, the agency’s senior air monitoring specialist.
ORCAA has air quality monitoring stations at Cheeka Peak near Neah Bay, in Port Angeles and in Port Townsend that measure air-borne particulate matter 2.5 microns in diameter or larger.
In the summer, a typical air quality advisory score for the North Olympic Peninsula is lower than 30, representing a rate of only 2 to 6 particles per hour, Hadley said.
Air quality advisory categories are:
■ Good — 0-49.
■ Moderate — 50-99.
■ Unhealthy for sensitive groups — 100-149.
■ Unhealthy — 150-199.
■ Very unhealthy — 200-249.
■ Hazardous — 250 and above.
On Sunday evening, the Cheeka Peak air monitoring station reached a score of 186 — categorized as “unhealthy” on the ORCAA scale.
Under an “unhealthy” air advisory, everyone should limit time spent outdoors, avoid exercising outdoors, including sports teams, and choose non-strenuous indoor activities.
People with asthma, respiratory infection, diabetes, lung or heart disease, those who have had a stroke, infants, children, pregnant women and those older than 65 should stay indoors.
In Port Angeles, the score reached 113, and in Port Townsend the score topped out at 107, representing air that was “unhealthy for sensitive groups.”
Under an “unhealthy for sensitive groups” advisory, people than average may have breathing problems or have worsened symptoms of existing asthma or lung disease.
People with heart or lung disease, asthma, diabetes, infants, children, adults older than 65, pregnant women, or who have had a stroke should limit time spent outdoors, according to the advisory.
Hadley noted that the Port Angeles monitor showed a score of 167 on Saturday night, during the height of fireworks, and dropped back to “good” levels by 3 a.m. Sunday morning.
Current ORCAA air quality scores can be monitored online at www.orcaa.org.
Five major fires have been burning on Vancouver Island.
According to the British Columbia Wildfire Service website, the two largest fires were uncontained on Monday, with three others alo remaining active.
■ Boulder Creek Fire, 14 miles northwest of Pemberton, exceeded 12,000 acres and was zero percent contained.
■ Elaho Fire, 42 miles west of Pemberton, has burned more than 49,000 acres, and was zero percent contained.
■ Dog Mountain Fire at Sproat Lake, was 237 acres and burning aggressively on a mountaintop on a peninsula almost entirely surrounded by the lake.
■ Old Sechelt Mine Fire, 1 mile west of Sechelt, was 197 acres, 40 percent contained.
■ Tsulquate River Fire, 1 mile west of Port Hardy, was about 40 acres, 20 percent contained, and was showing extreme fire behavior.
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Reporter Arwyn Rice can be reached at 360-452-2345, ext. 5070, or at arice@peninsuladailynews.com.