Hot Weather, Cool Clothes: How Fabrics Combat Heat

Feeling the heat this summer? It could be what you’re wearing.

“We human beings really need to balance heat and moisture to feel good,” Guowen Song told Time.com. He's the head of Iowa State’s Lab for Heat and Thermal Protection Research. “That’s why in different seasons we wear different things. The clothing mediates how much heat dissipates into the environment.”

For humans, beating the heat all boils down to sweat. The hotter it gets, the more we sweat. As that sweat evaporates, it carries away heat. If the sweat can’t evaporate, the skin can't cool as well. Of course, you could go bare-armed and bald-headed, but that’s not always appropriate. So finding clothes made of fabric that lets sweat do its thing is key.   

“If the sweat’s just sitting on you, then it’s not evaporating, and therefore it’s never actually leaving the surface of your body and it’s harder for your body to stay cool,” Kimberly McMahon told Time. She works for the National Weather Service. She recommends looser clothes. Even among the breeziest of blouses, though, certain fabrics rule for keeping cool.

Cotton can be comfy. But at the microscopic level, it’s made of dense, tangled fibers that trap sweat instead of letting it evaporate. Wool is even worse. Linen, though, has straighter fibers that allow sweat to wick through. And some synthetic fibers, like polyester and nylon, have been designed to let sweat pass through. That holds true even if the garment is tighter. Search your closet for clothes labeled “quick drying,” “sweat-wicking,” or “athletic wear.”    

Reflect: How do you choose what to wear when it's really hot outside to stay cool and comfortable?