Temperatures in western Europe are soaring and while they may not reach the record highs set in 2022, experts are warning this heatwave could be even more dangerous.
The reason is high humidity, which makes the heat much harder to cope with.
Dr Heather Massey from the Extreme Environments Laboratory at the University of Portsmouth told the Science Media Center (SMC) that while the human body has ways of coping with the heat, this becomes less effective when humidity is elevated.
“Higher moisture levels in the air reduce the effectiveness of sweating that would cool the body,” she said.
Hugh Montgomery, professor of intensive care medicine at University College London said in a SMC briefing on Tuesday that sweat will evaporate really quickly in dry air, cooling down the skin.
“If you are in a very humid atmosphere, let’s say 100% humidity, or close to, then it’s impossible to evaporate that water. So, there can be no cooling effect, and sweat will just drip off you, and dripping sweat has no cooling benefit at all,” he said.
To illustrate the problem, Montgomery said that temperatures of 36 degrees Celsius (97F) can become dangerous in 65% humidity, while at 42 Celsius (107.6F) 35% humidity can be “pretty lethal.”