Humidity is a way to describe how much moisture (water vapor) is present in the air. “Relative humidity” is typically how we refer to levels in a home and it’s expressed as a percentage. The ratio describes the current amount of water vapor in a given area relative to the amount that would be present if the air were saturated.

The more moisture there is in the air, the higher that number will be. Warmer temperatures can hold more moisture, which is why these levels often remain high in many places during the summertime. As mentioned above, that can translate to higher levels of humidity indoors, and that is a situation we want to avoid.

When the humidity is too high, it can cause poor indoor air quality, structural issues, and microbial growth. (Mold can grow at a relative humidity level of 60 percent.)

However, you also don’t want it to be too dry indoors! That can lead to adverse health reactions like respiratory discomfort and structural issues like wood separation.

The ideal humidity level in a home should be between 35 and 50 percent. Ideal humidity should be maintained not only for comfort but also for safety.