Maintain the Right Humidity for Health

Maintaining a comfortable level of humidity in your home is important to your good health. If a room is too dry, your nose and throat feel scratchy, and your hair and skin may be dry, too. When the humidity is too high, fungi and mites thrive, and household chemicals like formaldehyde can become respiratory irritants.

Bacteria and viruses can survive whether you have too much or too little humidity. But allergies and asthma afflict people more seriously when the humidity is too low or too high. So the best way to control these problems is to keep the relative humidity between 40 and 60 percent, ideally at about 50 percent.

Keeping the humidity level at around 50 percent also is good for your house. Dry air cracks wood and loosens furniture joints. It makes wooden windows contract, causing them to rattle on windy days and to let in air. Of course, dry air is the culprit behind static electricity, too. When clothes and carpet become dry, they cause electrostatic shock.

And another good thing about keeping the humidity level at about 50 percent is that it’s the ideal level to keep you warm. When it drops below 50 percent, a cold house feels even colder. The human body cools off by releasing moisture from the skin. When the air gets dry, the moisture evaporates faster and people feel cold rather than comfortable. That's why a dry winter draft cools more quickly than a humid winter draft.

Check the humidity level in your house with a humidstat or by looking at your windows. As the temperature outside cools, so do your windows, causing indoor air to condense and fog the glass. If you see only a small amount of moisture, your room probably is too dry. But if the window is so wet that the sill is soaked, the room is too humid.

To reduce humidity, install exhaust fans where humidity is generated, like in your bathroom and kitchen. Adding more vents and installing energy-efficient windows will help, as do dehumidifiers.

When your home is too dry, even a small humidifier helps. Or, set pans of water beside registers so the warm air will pick up water as it circulates.