Do You Need a Humidifier or a Dehumidifier?

A home can be the right temperature and still feel wrong. The missing piece is usually humidity: the amount of moisture in the air.

The number to know

Relative humidity is the moisture in the air as a percentage of what it could hold. For health and for your house, 30 to 50 percent is the target. A cheap digital hygrometer from a hardware store tells you where you are.

Too dry or too damp

• Too dry: itchy skin, chapped lips, static shocks, wood that cracks. This shows up mostly when the heat runs in winter.
• Too damp: musty smells, condensation on windows, mold and mildew, wood that swells, and warps. On the Gulf coast this is the usual problem.

What to do about it

A well-maintained central air conditioner removes a lot of moisture on its own. If the house still reads above 50 percent, a whole-home dehumidifier connected to your HVAC system finishes the job in every room. For one damp space, like a laundry room, a portable unit sized for that room can be enough.

Dry winter air is less common here, but a whole-home humidifier can help if the readings drop below 30 percent.