Using a humidifier, boiling water, adding water sources and hanging clothes to dry are some ways to increase a room's humidity. Humidifiers range in size and capability. Some are made for distributing moisture throughout an entire house, while others are made just for one room. Humidity increases inside a room whenever water evaporates. Low humidity environments include desert areas and artificially-heated rooms. Low humidity can affect a person's health and some objects in the environment, such as wooden furniture.
Humidifiers create moisture in the air through several methods, including evaporation from fans, vaporizing water and ultrasonic vibrations. These devices contain reservoirs of water for this purpose. Adding too much moisture to the air promotes mold and dust mites population. As a result, the relative humidity of a room should not exceed 50 percent. Users may wish to install a hygrostat for monitoring and managing the humidity inside a house or room.
Using tap water in humidifiers causes minerals to be left behind after evaporation. These minerals cause layers of white dust containing calcium and other ions to form in these areas, particularly on devices that produce static electricity. This can be prevented by using soft water, which is water possessing low concentrations of ions.