What percentage of humidity encourages fungal and dust mite growth?

The correct percentage of humidity that encourages fungal and dust mite growth is 40%. This level of humidity creates an environment conducive to the proliferation of mold and dust mites because both thrive in warm, damp conditions.

When humidity levels rise above 40%, it typically provides enough moisture in the air for mold spores to activate and begin growing, as they require a certain level of moisture for their reproductive cycle. Additionally, dust mites, which feed on organic debris like dead skin cells, also favor environments with higher humidity; they tend to thrive in conditions where the humidity is consistently around or above this threshold.

In contrast, lower levels of humidity, such as 20% or 30%, do not provide sufficient moisture for these organisms to flourish, thereby limiting their growth potential. A humidity level of 50% is often considered too high, but it is at the 40% level where conditions start to become favorable for both mold and dust mites.