Montreal public health officials have released a preliminary report looking at the factors that they believe contributed to 53 heat-related deaths around Canada Day.

The majority of those who died during the June 30 to July 5 heatwave – the city’s deadliest since 2010 – were men older than 50 who lived alone, according to the preliminary report.

Other risk factors included mental health problems, alcohol and drug dependency, cardiovascular and respiratory conditions and a lack of access to air conditioning.

In fact, none of those who died had air conditioning.

About three quarters of those who died lived in a private residences while four lived in rooming houses and eight lived in seniors homes. The statistics do not include deaths that may have occurred in hospitals.

Daily highs ranged from 31.7 C and 35.3 C during the heatwave and the humidity made it feel as warm as 45 C.

The report also says that deaths were clustered in neighbourhoods known as “heat islands” where temperatures can be up to 10 degrees higher.

Dr. David Kaiser from Montreal Public Health said that heat islands are dense areas with a lot of concrete and not much vegetation.

Montreal city councilor Mindy Pollak said that expanding greenery and removing asphalt are two ways that the city could reduce the risk of heat islands.

With a report from CTV Montreal’s Kelly Greig