In our dry climate, an in home whole house humidifier can be very helpful. The only draw-back to humidifiers is that they require maintenance. Most humidifiers are what is called a bypass humidifier. This means pressurized warm air from the supply plenum is brought through the humidifier and run across a wet pad that introduces moist air into the return plenum. This moist air is then distributed throughout the home. Bypass humidifiers work effectively except they really only work when the furnace is heating. A better (although more expensive) approach is a steam humidifier. A steam humidifier actually converts the water (liquid) to steam (vapor) which is then introduced into the air duct system. With a good steam humidifier a person has to be careful to not over humidify their home since this can create mold. With proper maintenance, a humidifier can help to alleviate many of the health issues that come from living in a dry arid climate. See Pictures of a non-maintained humidifier and new steam humidifier.