Many people hear the word “humidity” and immediately assume it’s something negative. After all, we’re told time and time again that when it comes to feeling uncomfortable in the summer, it’s not the heat so much as the humidity that does the real damage.

While humid places can be uncomfortable when temperatures soar in the summer, the reality is that humidity is needed to keep us safe, comfortable, and in good health. Humidity refers to the amount of water vapor in the air, which affects how we breathe and how we sweat. (For easy reference, a jungle has high humidity; a desert has almost none.)