Improve indoor air quality

Many of us use humidifiers and dehumidifiers in our homes for various reasons: to add moisture to the air during our cold, dry winters; to eliminate the dampness in our basements; to improve the air for family members with allergies and other health problems.

But when we use these devices, we don't expect them to do more harm than good. With new homes being built more air-tight to save energy, indoor air pollution can be a problem in many homes. According to Mark Salerno, district manager, Greater Toronto Area for the Canada Mortgage and Housing Corporation (CMHC), the air in our home can often be much worse than the air we breathe outdoors.

That's why proper maintenance and use of your humidifier or dehumidifier is important. Since most Canadians spend about 90 per cent of their time indoors, according to Health Canada, you want to ensure the air you and your family breathe is not adversely affecting your health.

How do you control the dampness in your home?
In relation to respiratory effects, the most important indoor contaminants to eliminate are second-hand tobacco smoke and allergens from, for example, dust mites (which thrive in humid conditions) and cats, says Dr. Susan M. Tarlo, a respiratory physician at Toronto Western Hospital, Asthma and Airway Centre. These common indoor allergens have been linked to asthma severity. Other pollutants, like mould resulting from damp conditions can also lead to a number of health problems including asthma or allergic rhinitis.

There are several indications that your home has too much humidity, says Salerno. These include:
• A damp or musty odour, detectable when you enter your home.
• A buildup of white or black spotting on exposed basement foundation -- an indication that mould is growing.
• Condensation on the windows.

"Dehumidifiers can be helpful for humid environments," says Tarlo. However using a dehumidifier for a roof -- or basement leak is an ineffective solution and any traces of mould should be eliminated immediately. "In terms of dealing with humidity, it's important you deal with the cause of the problem," says Salerno. But if your kitchen and bathroom tend to generate a lot of moisture, and your exhaust fans are not eliminating it properly, a dehumidifier can be a good option to control dampness.

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To ensure your dehumidifier does not contribute to indoor air contaminants, empty the tank frequently and wipe surfaces dry. Refer to the original manual for specific maintenance tips.

Salerno suggests purchasing an inexpensive tool called a hygrometer (humidity sensor), found at most hardware stores, to measure the relative humidity of your home. This can help you determine the settings for your dehumidifier. Tarlo recommends a relative humidity of 40 to 50 per cent during the winter months. 

How do you add humidity to your home if it is too dry?
Winter, in particular, can cause a very dry indoor environment. Signs that there is not enough humidity in your home include: static electricity, dry, chapped lips and skin, nose and throat irritation, and breathing problems.

If humidifiers are used for very dry environments, then care should be taken not to over-humidify the area," warns Tarlo. This is an instance where a hygrometer would also come in handy to test relative humidity levels.

It is important to clean your humidifier regularly to prevent fungal or other bio-organism contamination, says Tarlo. Refer to your model's manual for proper cleaning instructions. "Bioaerosols from contaminated humidifiers can cause allergic symptoms and also a condition called humidifier fever, with flu-like symptoms."

For more information on controlling the humidity levels in your home, click on the following links:

• Measuring Humidity In Your Home from the CMHC.
• About Indoor Air from the Canadian Lung Association
• Dampness, Mould and Indoor Air from Health Canada's It's Your Health section.
• Tips for use and care of humidifiers and dehumidifiers from American Lung Association Health House.