Summer in the US regularly pushes past 100°F, and for most of us, the reflex is probably the same: turn on a box fan and hope for relief. According to the EPA guidance on extreme heat and indoor air quality, that reflex has a built-in limit. The agency warns that electric fans stop preventing heat-related illness once a room temperature reaches the mid-90s or higher, because a fan does not cool the air; it simply moves it around. Here's what's really happening inside your body when a fan stops working, and what current research says about it.
Why does your fan have a temperature limit
