In 1980, the Canadian government banned the use of urea formaldehyde foam insulation in houses. Although many in the real estate industry think the government over-reacted to the potential dangers of the insulation, Health Canada has continued to monitor the levels of formaldehyde from other sources in indoor air. It is now proposing new guidelines for short and long-term exposure.

Formaldehyde, a colourless gas, is present at low levels in most houses. It comes from combustion sources such as cigarettes and smoke from indoor wood-burning appliances, as well as engine exhaust that may filter into the house from cars, lawnmowers and snowblowers being operated outside.

It's also used as a disinfectant and a preservative in the manufacturing of building materials and furniture, including wood products such as particle board, medium density fibreboard, moulded plastics, carpeting, drapes, paint, varnish, and wallpaper. Formaldehyde is present in some cleaning materials, cosmetics such as nail polish, and even permanent press clothing and sheets.

At high levels of exposure (thousands of parts per billion or higher), formaldehyde causes cancer of the nasal cavity, says Health Canada. At moderate levels (hundreds of ppb), it can cause temporary burning in the eyes or nose and a sore throat. Heath Canada says some studies show that people exposed to formaldehyde levels from 50 to 100 ppb for long periods of time are more likely to experience asthma-related respiratory symptoms such as coughing and wheezing, but that the studies are not conclusive.

The ministry measured the air quality inside homes in Prince Edward Island and Ottawa in 2002 and 2003 and found that the levels of formaldehyde ranged from about two ppb to 81 ppb. It is proposing that the new air quality guideline for formaldehyde should be set at 100 ppb for short-term (one hour) exposure, and 40 ppb for long-term (eight hour) exposure. This new guideline is intended to assist the work of public health inspectors.

Health Canada says the amount of formaldehyde in Canadian homes is well below a level that would cause concern about cancer, and that studies for other health related problems from the gas have not been conclusive. "However, it is still a good idea to follow some simple steps that will help lower your exposure to formaldehyde," says an updated Health Canada information bulletin.

Here are some of its recommendations:

• Don't let anyone smoke in your house.

• Keep your wood-burning appliances in good repair so no smoke seeps into the house. Consider upgrading to an advanced combustion fireplace or wood stove.

• When buying furniture made out of particleboard or medium density fibreboard, buy items that are covered with plastic laminate or coated on all sides. You can also seal unfinished sides to reduce the amount of formaldehyde released.

• Control moisture levels in the house. Health Canada says products release formaldehyde into the air at a faster rate when humidity levels are high.

• Wash permanent press clothing and sheets before you use them, and air out products like permanent press drapes before you bring them into the house.

• Do not run gas engines in your attached garage. Start your car and drive it out of the garage immediately, so it does not idle in the garage. Close the door so the exhaust doesn't come into the garage. Start snowblowers and lawnmowers outside.

Health Canada says that controls on sources of formaldehyde seem to be working, as recent studies show that concentrations of the gas are lower than they were in the past.

"Health Canada continues to track new science on the health effects and sources of formaldehyde, and takes action to change guidelines, controls or labeling requirements when the science indicates it is needed," says the ministry's information bulletin. It is also conducting a number of new studies to determine the levels and sources of chemicals, including formaldehyde, inside the home.

Canada Mortgage and Housing Corp. (CMHC) also has several indoor air quality research projects on the go. These include studies about the relationship between indoor air quality and respiratory health, methods for dealing with mould problems, and even the health effects of marijuana grow homes and illegal drug laboratories.

Published: August 25, 2005

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Jim Adair is editor of REM: Canada's Real Estate Magazine, a business publication for real estate agents and brokers. He is also consulting editor of Homes & Cottages, Canada's largest building and renovation magazine. Email jimhc@pathcom.com.