The purpose of a humidifier is to increase the moisture content of the air in the room or home. Humidifiers are often used in the winter in homes and buildings where heating systems are in heavy use. They can be bought as small room units or whole house units.
Humidity is a measure of how much moisture is in the air compared to the maximum amount possible. This measurement is typically given in terms of a percentage, rarely as a ratio or fraction. Low humidity in the air, otherwise known as dry air, can exacerbate many respiratory conditions. It can lead to dry lips and skin, nose bleeds and even the common cold. A humidifier can increase the humidity of the air to improve comfort and respiratory health.
A humidifier must be cleaned regularly to prevent the growth of mold and bacteria in the device, which will be blown around the house. If moisture is found on windows and other surfaces, the appliance should be turned off to prevent contamination.