Some areas of the country have very dry conditions that may require the use of a humidifier to prevent respiratory infections and other problems associated with breathing air that is too dry. You may find that winter weather in your area is particularly drying. In cases like these, use an air humidifier in the common areas of your home to increase the moisture to between 30 and 50 percent. Remember that when the winter weather gives way to spring and you stop using heat, you should also stop using your home humidifier. Too much moisture in the air is just as bad as not enough!