Officials in Montreal and the Eastern Townships are urging people to check on their neighbours and loved ones, especially those without access to air conditioning, as the heat wave gripping the regions peaks and is being blamed for 18 deaths. The toll of heat-related deaths in the province rose by eight in total between Tuesday and Wednesday. Twelve have been confirmed in the Montreal area, five in the Eastern Townships and one in Laval. The wave started last Friday and is the worst to hit Quebec in decades. Montreal Mayor Valerie Plante said at a news conference that, "we're doing everything we can." She pointed to the city's response, which includes opening swimming pools and air-conditioned areas to the public, distributing water to those in need and having first responders checking in on vulnerable citizens. Plante said 15,000 people were visited by firefighters and police yesterday to make sure they could cope with the heat. She also called on the public for help responding to the heatwave. "I'm counting on Montrealers to knock on doors, maybe of a neighbour, just to find out if the person is OK. It's a team effort," Plante said. "Think about your neighbours; think about your family members, grandpa, grandma; think about your kids, your friends," said Melissa Genereux, the director of public health in the Eastern Townships. "Why not give them a call, a visit, take them out of the house ... a bit of cool air could do some good and save lives." Genereux and David Kaiser, of Montreal's public health department, have said those who died in both regions didn't have air conditioning in their homes and had health issues. Speaking on CBC's The Current, Kaiser said temperatures recorded by paramedics in these cases reached the high 30s inside the victims' apartments. "What we know about why heat kills people is that people with underlying medical problems are more vulnerable to accumulating heat," Kaiser said. "So, after a couple days of being hot and living in a place with no air conditioning, the heat just overwhelms the body's capacity to adapt." Kaiser said city workers are knocking on doors to identify people in similar situations and get them medical help, or to a cooling shelter. The hot and humid air mass over southern Quebec will persist through Thursday, but lift by Friday, when a cooler 24 C is expected to settle in, according to Environment Canada. "Humidex values will reach near 40," states Environment Canada's heat warning for the Greater Montreal area. "However, conditions will grow even more uncomfortable on Thursday with humidex values reaching 43." Today, temperatures are expected to reach a high of 34 C with a very high UV index. Thursday should be more of the same. Urgences-Sante said it had received more than 1,200 calls a day since the heat began, representing a 30 per cent increase to its busiest days. The ambulance service urges people to first seek help from friends and family or to call 811 first for tips on how to handle minor health issues where life is not at risk.