Air pollution in Yakima and elsewhere in Central Washington is forecast to worsen into the weekend, prompting the National Weather Service to issue an air stagnation advisory.

The advisory, issued Friday, will remain in effect until Monday.

North central Oregon also is being affected by the rising pollution.

Small children and the elderly are especially at risk during air pollution episodes.

The Yakima Regional Clean Air Authority imposed the strictest burn ban possible Thursday afternoon because of the worsening pollution.

The Stage 2 ban prohibits all outdoor burning and use of wood-burning home heating appliances unless they are the sole source of heat.

An inversion is trapping pollutants near the surface. Without sufficient wind to scour out the pollutants, air quality will continue to worsen, the weather service said.