Environment Canada issued a smog warning Sunday evening for the greater Montreal area, including Châteauguay Longueuil and Laval, as well as for Quebec’s Mauricie region.

The agency is warning people with respiratory problems, such as asthma, to avoid intense physical activities until it lifts the warning.

“High concentrations of fine particulates are expected and will result in poor air quality,” the warning, posted to Environment Canada’s website, said.

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The warning noted wood heating is the main source of those fine particles contributing to smog in the winter — more even than industrial activities and transportation.

“Montréal residents – Stop using your wood-burning stove or fireplace until the smog warning has been lifted,” the agency wrote.

It’s a bylaw in Montreal to do so.

“We can all help improve air quality by doing simple things, such as limiting the use of fireplaces and wood-burning stoves, opting to use public transit, reducing our driving speed and not letting our car engines idle unnecessarily,” Environment Canada said.

The agency did not say when it would be able to lift the warning.

The areas affected by the warning in Mauricie include:

• Lac-aux-Sables
• Louiseville
• Matawin and the Mauricie National Park
• Sainte-Anne-de-la-Pérade
• Shawinigan
• Trois-Rivières.