With Toronto's heat wave in its third day, the city's chief medical officer of health says the high temperatures are definitely a health risk.

Dr. David McKeown told CTV News on Tuesday that the elderly, those with chronic health problems and those who live alone are at particular risk.

He asked people, particularly landlords, to check on those who might be vulnerable.

"Make sure they're safe, make sure they don't need water, take them to a cool place if they need help," he said.

Toronto's temperature reached 33 degrees Celsius at the Pearson International airport weather station. With the humidity figured in, it felt like 41 C. All of southern Ontario is under a humidex advisory, and all except the eastern-most fringe is under a smog advisory.

Paul Raftis, deputy chief of Toronto EMS, said that the service's call volume has increased by about 20 per cent with the advent of the heat.

"Our breathing related emergencies are up by 50 per cent," as are fainting incidents, he said.

Cases of heat exposure are up by 100 per cent, he said.

Raftis had the following advice:

  • drink lots of water
  • avoid alcohol
  • stay cool
  • avoid strenuous outdoors activity between 11 a.m. and 4 p.m.
  • never leave the elderly, pets or children unattended in a vehicle

In an emergency, don't hesitate to call 911, he said.

Elaine Smyer, the city official in charge of cooling centres, said they have seven cooling centres, but have opened an eighth specifically to provide services to those with mobility issues or are elderly.

Here are the cooling centres:

  • Metro Hall - 55 John St. (24 hours)
  • East York Civic Centre - 850 Coxwell Ave. (11 a.m. to 7 p.m.)
  • North York Civic Centre - 5100 Yonge St. (11 a.m. to 7 p.m.)
  • Driftwood Community Centre - 4401 Jane St. (11 a.m. to 7 p.m.)
  • Etobicoke Olympium - 590 Rathburn Rd. (11 a.m. to 7 p.m.)
  • McGregor Community Centre - 2231 Lawrence Ave. E. (11 a.m. to 7 p.m.)
  • Centennial Park Community Centre - 1967 Ellesmere Rd. (11 a.m. to 7 p.m.)

Smyer said it you can't get to one of the designated centres, go to any air-conditioned public building.

"When an alert is declared, those who need assistance or have heat-related inquiries may call the Canadian Red Cross Heat Information Line at 416-480-2615 between 9 a.m. and 9 p.m." the city said.

For those who want a late-night dip, the city has extended closing time until 11:45 p.m.

  • Monarch Park Pool, 115 Felstead Ave.
  • Regent Park Pool, 450 Gerrard St. E.
  • Alex Duff Memorial Pool, 779 Crawford Ave.
  • Alexandra Park Pool, 275 Bathurst St.
  • MacGregor Park Pool, 2231 Lawrence Ave. E.
  • Smithfield Pool, 175 Mount Olive Dr.
  • Cummer Park (indoor pool), 6000 Leslie St.

High Park outdoor pool is open until 9 p.m., and the Weston Lions outdoor pools is open until 8 p.m.