Smoke from the Williams Flats Fire near Grand Coulee Dam was drifting south over the Tri-Cities on Sunday afternoon.
Skies had turned hazy and the air quality in the Tri-Cities had deteriorated to a level considered unhealthy for some people by late Sunday afternoon, according to the Benton Clean Air Agency in Kennewick..
They include children, seniors, pregnant women, people who smoke and those with health conditions such as asthma, diabetes, lung disease, heart disease or a history of stroke.
Those people were urged to limit their time outdoors.
The air quality also had deteriorated in Sunnyside to the west of the Tri-Cities and Ritzville to the north.
The Williams Flat Fire started Friday from lighting strikes as thunderstorms moved across the Colville Indian Reservation. Sunday afternoon it had burned nearly 10,500 acres.
Steep slopes, limited access and primitive conditions were hampering work to contain the fire. None of the fire had been contained Sunday morning.