As the colder weather sets in across southern Quebec, wood heating is being blamed for a smog warning in the Greater Montreal area and parts of the Laurentians, Montérégie, Lanaudière, Mauricie and Quebec City regions. …”High concentrations of fine particulates are expected and will result in poor air quality,” the warning says.  Wood heating is the main source of those fine particles that contribute to smog in the winter — more even than industrial activities and transportation, according to Environment Canada. “Montreal residents — stop using your wood-burning stove or fireplace until the smog warning has been lifted,” the warning reads. It’s a bylaw in Montreal to do so.