Unless you live somewhere that’s moderate year round, chances are you’ve relied on a air cooling fan to make an otherwise steamy room more bearable. While fans don’t always add cold air to the mix, they help circulate the air so that our bodies can better cool down. In some cases, though, air conditioning is a much better option. “If a person has allergies, asthma, or eczema that are exacerbated by pollen, then it's best to use air conditioners, which filter out pollen and allow the windows to be closed,” says Hadley King, M.D., NYC-based dermatologist and clinical instructor of dermatology at the Weill Medical College of Cornell University. But the reality is that air conditioning isn’t always available—and in some cases, skin conditions like eczema can be triggered by heat. In these situations, a cooling fan can be helpful, says Hadley, as long as it’s used c...