Human tolerance to high temperature, humidity, lower than thought

2 July 2022

New research from Pennsylvania State University (PennState) shows human tolerance to temperatures — in situations where humidity is at one hundred percent — isn’t as high as previously thought. And that’s for younger people in good health.

For those not in that category, temperatures of 31°C (wet-bulb) would be far too high. Such temperatures are a regular occurrence in many parts of the world, certainly areas of Australia during the height of summer, so temperatures in the high thirties, or even forties, with one hundred percent humidity, pose a danger for just about everyone.

But in their new study, the researchers found that the actual maximum wet-bulb temperature is lower — about 31°C wet-bulb or 87°F at 100% humidity — even for young, healthy subjects. The temperature for older populations, who are more vulnerable to heat, is likely even lower.