The Conversation – Our lab found heat + humidity gets dangerous faster than many people realize: “Heat waves are becoming supercharged as the climate changes – lasting longer, becoming more frequent and getting just plain hotter. One question a lot of people are asking is: “When will it get too hot for normal daily activity as we know it, even for young, healthy adults?” The answer goes beyond the temperature you see on the thermometer. It’s also about humidity. Our research shows the combination of the two can get dangerous faster than scientists previously believed. Scientists and other observers have become alarmed about the increasing frequency of extreme heat paired with high humidity, measured as “wet-bulb temperature.” During the heat waves that overtook South Asia in May and June 2022, Jacobabad, Pakistan, recorded a maximum wet-bulb temperature of 33.6 C (92.5 F) and Delhi topped that – close to the theorized upper limit of human adaptability to humid heat. People often point to a study published in 2010 that estimated that a wet-bulb temperature of 35 C – equal to 95 F at 100% humidity, or 115 F at 50% humidity – would be the upper limit of safety, beyond which the human body can no longer cool itself by evaporating sweat from the surface of the body to maintain a stable body core temperature. It was not until recently that this limit was tested on humans in laboratory settings. The results of these tests show an even greater cause for concern..”