Montreal has worst air quality of any large city

Quebec province's most populous city had 'unhealthy' air quality according to IQAir, which tracks pollution around the globe, as hundreds of wildfires burned across the country.

Environment Canada issued smog warnings in several Quebec regions due to the fires, saying, "high concentrations of fine particulate matter are causing poor air quality and reduced visibilities," with conditions to persist until Monday morning.

The agency urged residents to avoid outdoor activities and wear face masks if they must go outside.

Outdoor pools and sports areas have been closed and multiple outside events, including concerts and sports competitions, have been cancelled due to the unhealthy smog.

"It's really like a fog, except it's smoke from the forest fires. It's really hard to breathe, and it stings the eyes a bit too," said 18-year-old Fauve Lepage Vallee, lamenting that a festival she was due to attend had been cancelled.

There are 80 active forest fires in Quebec, according to Quebec's forest fire protection agency, SOPFEU, with several growing over the weekend due to dry weather and high temperatures.

"The extent of the smoke is making it particularly difficult for air tankers and helicopters to be effective," SOPFEU said.

However, "significant amounts" of rain are expected on Monday or Tuesday in the northwest of the province, it added.

On Wednesday, 119 French firefighters are due arrive in Quebec to relieve a contingent of their compatriots in the field since early June.

"They will also be deployed to Roberval," 250 kilometers (150 miles) north of Quebec City, for a 21 day mission, said Stephane Caron, a spokesman for SOPFEU.

Across the country, the Canadian Interagency Forest Fire Centre (CIFFC) lists more than 450 active fires, some 240 of which are deemed out of control.

Canada is experiencing an unprecedented year of fires, with more than 7.4 million hectares burned since the beginning of January.