A smog warning for Greater Montreal, triggered by a record-number of raging forest fires, ended Wednesday afternoon.

Environment Canada still considers air quality in the region "high risk." It expects conditions to improve throughout the day, bringing it to "low risk" by Thursday.

Quebec's forest fire prevention agency reports over 150 forest fires burning in the province, with just under 100 deemed out of control.

That leads to a high concentration of fine particles in the air.

Normally, the fine particle concentration in Montreal is around seven micrograms per cubic metre, according to David Kaiser, associate medical director at Montreal Public Health.

On Tuesday, levels hit between 70 and 80.

The situation is even worse in Ottawa, where concentrations are ten times higher than that, said Kaiser.


High concentrations of fine particles can cause itchy eyes, runny nose, sore throat, headache and a cough.

In serious cases, you can experience shortness of breath, wheezing, dizziness, chest pain and heart palpitations.

On Wednesday, Montreal's health department advised people to avoid strenuous outdoor activities. Those with heart and lung conditions, children and the elderly are especially urged to take it easy.

"When the air quality is poor, I would not exercise outdoors, quite frankly," said Montreal epidemiologist Dr. Christopher Labos.

"You're going to be breathing in that smoke, and that particulate matter, and that is going to damage the lungs. You'll be ok in the sense that nothing is going to happen to you in the next 24 hours, but that repetitive damage to your lungs is setting you up for long-term dysfunction," he said.

To minimize risk, you can turn off your air exchange system or put it into circulation mode, stay inside and close windows and doors.

N95 masks can also help limit your exposure to particles, said Dr. Labos.

Anyone concerned about their symptoms is advised to call Quebec's 8-1-1 medical service line.


Laval commuters can take the bus at a discounted rate Wednesday in an effort to reduce the number of cars on the road.

Laval's transit authority (STL) has reduced its bus rate from $3.50 to $1 for the day.

"The STL's Smog Alert is a unique initiative in Canada. It aims to promote the use of public transit rather than the car when the air quality deteriorates to the point of falling below acceptable standards," a release from the agency reads.

Laval has offered reduced bus fares on hazy days since 2008.