Northern Health and the environment ministry have expanded a road dust advisory in northwest BC.
Officials say air pollution caused by road dust, which first popped up in Burns Lake, has now been extended to Houston and Smithers.
Gravel left over from winter sanding activities is getting the blame for elevated levels of coarse particulate in the air.
People with chronic underlying medical conditions are being advised to postpone strenuous exercise near busy roads until the advisory is lifted.
Poor air quality is likely to stick around some precipitation hits the ground or the winter sand material is swept up.