More than 30 people have died during a heatwave in Canada, with most victims being men living alone in private apartments without air conditioning.

Montreal’s public health department spokesman Dr David Kaiser said
 the social aspect – living alone and not having another place to go to cool down – typically plays a major role in heat-related deaths in the city.

“Montreal is [a] gigantic heat island,” he said, referring to an environmental phenomenon caused by a lack of vegetation and an abundance of concrete.

Dr Kaiser said many of the victims were men aged over 50, living alone in private apartments and seniors’ residences.

Health authorities in the Canadian province of Quebec said on Thursday that 33 people have died from heat-related complications in the last few days.

Eighteen of those deaths have come in Montreal, where humid temperatures climbed past 43 degrees Celsius.

“It’s not surprising,” Dr Kaiser said.

“Heat risk in an urban setting is a combination of medical, social and environmental exposures.”

“The elderly, people with chronic diseases and people with mental health problems are more at risk.”

Dr Kaiser said there were “micro heat islands” throughout the city, particularly in some of the poorer areas.

Canadian Prime Minister Justin Trudeau tweeted a warning to families to protect themselves and their loved ones during the record heatwave.

My thoughts are with the loved ones of those who have died in Quebec during this heat wave. The record temperatures are expected to continue in central & eastern Canada, so make sure you know how to protect yourself & your family: https://t.co/JSPPsU80x9

— Justin Trudeau (@JustinTrudeau) July 4, 2018

-with AAP