The ideal indoor humidity level for a home falls in the range of 35 to 50 percent. This range provides the optimal comfort and health.
Keeping the humidity level below 50 percent in a home helps to prevent the population growth of mold and dust mites, both of which are common indoor allergens. Additionally, high humidity levels attract pests and can cause rot in a home as water condenses inside the walls.
There are dangers, however, in keeping the humidity too low. Humidity much lower than 35 percent dries out the skin, causes static electricity and potentially causes breathing problems.