Because of the reduced humidity levels in the winter, many people suffer health symptoms of dry air. Cold symptoms, allergies, dry skin, and other problems can be the result of dry air. In dry climates, people can suffer these problems year-round. Dry air can also cause problems in the home, such as static electricity, cracked paint, dry furniture, and peeling wallpaper. House humidifiers are used to increase the moisture level of the air and reduce associated problems.

Console models are larger units and are designed for floor use. Usually enclosed in a cabinet, they are made to control the humidity of multiple rooms. These house humidifiers use cool mist, or evaporative technology. This means that water sits in a holding tank and is drawn out by a cloth or foam wick. A fan then blows it into the air through a filter. The filter sifts out bacteria and other impurities. Then the water evaporates into the air. This type of humidifier will slightly cool the air, a plus for warm climates. The filters in these units need to be cleaned or changed regularly, depending on manufacturer instructions. Failure to follow the cleaning and care instructions can lead to the growth of mold and bacteria. When buying a console humidifier, check the prescribed coverage area to determine its appropriateness for your space. All console humidifiers use cool mist, or evaporative, technology. Console humidifiers typically cost $90 to $120.

Room humidifiers, on the other hand, are designed to be used in one room only. Also called tabletop humidifiers, these units are smaller and generally cost $40 to $80. Room humidifiers come in two varieties: cool mist as used in the console models; and warm mist, in which the water is heated before being dispensed into the air. Warm mist humidifiers do not use filters"the heating mechanism kills the bacteria. However, they do require more energy to heat the water. Warm mist humidifiers warm the air slightly, allowing users to lower the setting on their heaters. When picking out a room humidifier, check the prescribed coverage area. Very large rooms may require more than one unit.

Just as low humidity can cause problems, so can high humidity. The U.S. Environmental Protection Agency recommends humidity levels stay between 30 and 50 percent. Excessively high humidity can lead to the growth of mold and bacteria. To control the humidity level, it is important that your humidifier be equipped with a humidistat. This device is designed to keep humidity within acceptable levels.