Most people spend as much as 90 percent of their lives indoors, so the quality of your indoor air is important. You'll feel better — and be healthier — if you can keep the humidity in your house as close to the 50 to 55 percent level as possible. You can measure indoor humidity using a hygrometer, also known as a humidity or moisture meter.

If the humidity is too low, your house may crackle from static electricity and your sinuses, throat and skin feel dry. Dry air can cause sinus membranes to dry out, crack and become vulnerable to inflammation and infection. Dryness can also cause wall paneling, wood trim and hardwood flooring to shrink and joints to open.

The air is generally drier in the winter because cold air holds less humidity than warm air. Winter dryness in houses is frequently due to having too much dry outdoor air exchanged for the more humid indoor air. In cold weather, outdoor air is pulled into the home because of the "stack effect" — warm air rises and leaves through gaps in the upper part of the house and is replaced by cold dry air that enters through cracks in the lower portion. Houses with gas heating can be more susceptible to this effect because leaky ducts and chimneys contribute to accidental ventilation whenever the furnace is running. If the heating and cooling system ducts leak, that can also create negative pressure that pulls outdoor air into your home.

While many homeowners seek to solve the problem of overly dry air by adding a humidifier, the best approach is to improve the home's heating and cooling system and add caulking and insulation.

Leaky, poorly insulated houses can also contribute to excess humidity. In summer, the more humid outdoor air enters the home, and in winter, water condenses on the cold surfaces of uninsulated glass.

Signs of high humidity include condensation on cold surfaces and mold and mildew growth. Excess humidity in your home can lead to mold growth and increase the dust mite population, and both mold and dust mites are powerful allergens. Reducing indoor humidity below 60 percent will reduce mold and cause dust mites (microscopic spiderlike insects that cause many people allergy problems) to go dormant.

The best way to solve a high-humidity problem is to reduce the amount of moisture in the air inside the house.

Here are some of the typical sources of interior moistu

• People. A typical family of four can introduce up to two gallons of moisture per day from normal breathing and perspiration.
• Crawl spaces that do not have 100 percent of the exposed dirt covered with plastic can be a very large source of moisture. 
• Kitchen stoves with recirculating exhaust hoods that blow the moisture from the stove back into the room are a frequent source of problems.
• Bathrooms without ventilation, bath fans that are not used (especially after showers) and bath fans that are poorly ducted, underpowered and not able to properly remove moisture are another possible source.
• Unvented gas appliances pump in a lot of moisture into the home, as well as carbon monoxide.
• Dryers vented to the inside of the house and dryers with a leaky exhaust duct to the outside should be checked.
• Bulk moisture coming into the house from a leaky roof, basement, or from improper outside drainage can be the source of problems.

A state-of-the-art solution to uncovering heating and air conditioning problems is a Right Choice High Tech Audit, designed to help you reduce energy bills, increase comfort and improve air quality. In some cases, the source may be obscure or the remedy costly. During the high tech audit, our technician will perform a series of in-home, patented tests to provide an accurate, computerized, whole-house analysis.