“Humid conditions have their own sort of more perceptual limitations, that difficulty breathing, because it feels so claustrophobic,” Dr Cheng says.

“But in the dry environment, so far, the rate at which [their core temperature] is rising can be one-and-a-half to two times what we’re seeing with the more humid conditions.”

“It’s really for a lot of those nations, that don’t have a choice but to actually live in these conditions 24/7 … or for people in circumstances where air conditioning is not an option, or areas of the world where manual labour in the field is just sort of their way of life,” Dr Cheng says.

“A lot of those parts of the world that are most affected by it, are also the ones that have the least resources, I think, to deal with it.”

The researchers will keep testing the conditions on people until the end of the year.

But in the meantime, it’s given both the researchers, and Owen, an important glimpse into where the heat threshold of the human body lies.