In Canada, at least 130 people have died since last Friday following the extreme heat that hit the west of the country where the mercury is around 50 degrees.
- The heat dome is the result of the arrival of subtropical air which remains motionless for lack of strong winds and whose intensity is reinforced by an anticyclone.
- In all, 233 death reports have been recorded in Vancouver compared to an average of approximately 130 for the same period in normal times.
- In 2019, a study identified 27 reasons why heat can kill.
Absolute records have been shattered in Canada. For almost a week, an extreme heat wave has brought extreme temperatures which reached 49.5 degrees on Tuesday. In the Vancouver area, dozens of people have died suddenly in recent days due to the heat wave.
Air that stagnates and heats up on the ground
Normally, at this time, the Canadian city of Vancouver has temperatures around 21 degrees. For a week, the mercury has easily risen above 30 degrees and climbs above 40 degrees a few hundred kilometers away. For the third day in a row, the village of Lytton, some 260 km northeast of Vancouver, set a new all-time heat record for Canada, with 49.5 degrees, according to the Canadian weather service. The mercury also reached 42 degrees in the ski resort of Whistler, north of Vancouver, according to this service. Similar temperatures have been recorded in the northwest of the United States, in Portland or Seattle.
This sudden and brutal arrival of a heat wave is the consequence of a “heat dome”. This term, which is not a meteorological term, refers to a large mass of very hot air. Coming from Mexico thanks to depressions and anti-cyclones, the subtropical air now remains motionless above the western part of Canada and the United States due to the absence of strong enough winds at altitude. Added to this, in Canada, is an anticyclone that presses down on the ground and acts like a kind of bicycle pump that compresses the air and heats it up.
Older people most at risk
The Royal Canadian Mounted Police (RCMP, federal policing) and Vancouver City Police have separately announced that at least 134 people have died suddenly since Friday in the metropolitan area of Canada’s Pacific Coast. “Vancouver has never experienced such heat and, sadly, dozens of people have died from it“Vancouver police spokesman Steve Addison said in a statement. The province’s medical examiner services said they had “recorded a significant increase in the number of reported deaths” for a week. They received 233 death reports compared to around 130 on average for the same period in normal times.
The heat wave is directly responsible for this sudden increase in the number of deaths. “We believe the heat contributed to the majority of deaths”, confirms the federal police, adding that the majority of the victims are elderly people. “This weather can be deadly for vulnerable members of our community, especially the elderly and those with underlying health conditions.”, added an RCMP spokesperson, Mike Kalanj.
27 ways to die of hot
This episode confirms the deadly effect of heat. During the heat wave of 2003, 70,000 people died in Europe. Our body has mechanisms that allow it to adapt to temperature variations. This internal “thermostat” is regulated by the hypothalamus, the area at the base of the brain. But this mechanism only works up to a certain limit and past 40 degrees, the body loses its ability to self-regulate the temperature. From there to lead to death, there is still a gap.
In 2019, researchers at the University of Hawaii have identified 27 ways people die of heat, according to five mechanisms affecting seven organs. “Dying of Hot is akin to a horror movie where you have to choose between 27 terrifying endings”, concluded Camilo Mora, the lead author of the study. This is particularly due to the body’s defense mechanisms to cool the body which end up racing and turning against ourselves, endangering several organs.
When the body is racing
The cardiovascular system is then the first to fail. Blood pressure drops and the heart speeds up in an attempt to compensate for the lack of oxygen due to shifting blood flow. This phenomenon explains why people with heart disease are among the first victims during heat waves. The kidneys are also in danger because of dehydration which increases the reabsorption of water and salts, and damages kidney tissue. The brain is also put to the test because of an increase in blood pH which endangers cellular functions.
Ischemia and cytotoxicity are two other fatal phenomena caused by heat peaks. The first refers to an increase in blood flow in the periphery which is to the detriment of the central organs, which suffer from insufficient blood supply and therefore from a lack of oxygenation. The second explains a degradation of cell membranes which become permeable to toxins and pathogens. Finally, hyperthermia, or overheating of the body, is another consequence of heat that can kill. To avoid it, it is necessary at all costs to cool the body when the first symptoms appear, that is to say red skin, headaches or stomach pains, a weak or too fast heart rate.
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