Indoor Humidity
What amount is just right?

(As seen in the Toronto Star, written by Ed Borkowski)

If it took less than two years to figure out how to stop 12:00 from flashing across the VCR, you’re ready to tackle the task of setting the correct level on the furnace humidifier. You can ask the person who performs you fall furnace maintenance to set the humidifier for you, or you can do it yourself.

If you do it yourself, it’s important that you understand just what your current humidity level stands at.

Humidity is simply the amount of moisture or water vapour in the air. Each family member, as well as pets, produced moisture through breathing and perspiration. Even your indoor plants produce moisture. Water is added to indoor air through activities such as cooking, showering or bathing, dishwashing and doing laundry.

Although humidity is needed for our comfort and health, too much or too little humidity can produce problems.

There are two ends of the humidity spectrum. Too much humidity can result in condensation on windows, wet stains of walls and ceilings, mouldy bathrooms, musty smells, breathing problems and allergic reactions. Too little humidity can cause chapped skin and lips, scratchy nose and throat, static and sparks, and problems with electronic equipment.

The time of year is fast approaching when windows and doors will be kept closed to keep the cold out. But the moisture level in the air will remain unchanged. Humidity is usually measured as relative humidity(RH). RH is a percentage that indicates the amount of moisture in the air relative to the maximum amount the air can hold at that temperature. Warm air can hold more moisture than cold air, so that the RH of a sample of air will change as the temperature changes, even though the actual amount of moisture in the sample of air does not change. So as a sample of air cools, the RH will rise.

There are products called hygrometers that you can purchase to accurately measure the humidity level in your home. These instruments are readily available at hardware stores. However, experts have developed rules of thumb to help homeowners make decisions regarding humidity levels in their houses:
•The recommended indoor RH is 30% – 50%
•When the outdoor temperature is below -10C, the recommended indoor RH is 30%.

The limits should be used as guides only. Acceptable or comfortable humidity levels will vary from season to season, from house to house and from room to room in the same house. So take a look at the adjustment setting of your humidifier and see if it’s set properly–if you need to make an adjustment, make them gradually by either increasing or decreasing the desired level day by day. Your comfort level should improve.