When Fans Can Help You Beat The Heat

Summer’s not over yet. In case you only have a fan to help you cool off, you should know when it’s likely to help and when it’s likely to well, not. The U.S. Environmental Protection Agency recommends that people not use fans when the heat index temperature– a combo of the temperature and humidity– climbs above 99 degrees Fahrenheit. The World Health Organization and U.S. Centers for Disease Control and Prevention (CDC) warns that fans don’t help people stay cool enough when the temperature hits 90 degrees Fahrenheit or higher. A new study from the University of Sydney found that under hot and humid conditions, fans lowered participant’s core body temperature and reduced the heat-related strain on their heart, as well as improved their thermal comfort. However, in hot and dry conditions fans increased body temperature, the strain on the heart, and thermal discomfort. Researcher Ollie Jay explains, “Fans at any temperature up to 104 degrees Fahrenheit, where there is some kind of humidity, are beneficial. But as the temperature goes higher, if it’s dry then fans are progressively less useful and potentially detrimental.”