The Big Smoke is living up to its name on Monday evening.

A milky haze has enveloped Toronto, prompting Environment Canada to issue a special air quality statement for the city.

Smoke from forest fires in the northwestern part of the province is now hanging over southern Ontario, and it has lowered air quality and reduced visibility.

"High levels of air pollution due to smoke from ongoing forest fires are possible," Environment Canada said.

Several weather stations have reported elevated particulate matter levels and hazy conditions. When the smoke descends to ground level, air quality can deteriorate and visibility can be reduced, the federal agency added.

But there is relief in sight. Air quality is expected to improve on Tuesday when a cold front passes over the region.

Anyone exposed to wildfire smoke is urged to take extra precautions to reduce exposure.

"Wildfire smoke is a constantly-changing mixture of particles and gases, which includes many chemicals that can be harmful to your health," Environment Canada says.

Toronto residents may suffer increased coughing, throat irritation, headaches or shortness of breath.

Children, seniors and those with cardiovascular or lung disease, such as asthma, are said to be especially at risk.