Dr. Cheema says that what you see is what you breathe. "Especially with these particles and smoke, you know, they can sometimes embed in your lungs, and then it irritates the lungs, and then you start coughing. You start coughing up all that stuff," Dr. Cheema said.

Smoke from Canadian wildfires is once again blanketing the skies of Western Pennsylvania. More smoke is forecast to blow in Tuesday through early Wednesday. Lofted wildfire smoke is nothing new. Several plumes have tracked across our region over the past few summers.

The National Weather Service has issued a "hazardous weather outlook" for the Pittsburgh area beginning Tuesday, due to the chance of haze and poor air quality from Canadian wildfire smoke.