It's colorless, odorless, and toxic. It's present in many homes, although the homeowners don't know it. It's radon gas and is the cause of ten percent of all lung cancer deaths in Canada.
The presence and the dangers of radon gas were brought to the attention of the government of Canada way back in 1986.
In spite of the fact that, according to Dr. Fergal Nolan, "radon kills more Canadians every year than fires, drowning, accidental poisonings and air crashes combined", the issue wasn't properly addressed.
The current level for radon gas in a home deemed acceptable is four times higher than the minimum safe limit. Health Canada has finally figured out that many deaths can easily be prevented simply by cutting the exposure to this toxic gas.
Homeowners can do some things to help themselves. Seal cracks in walls and floors. Seal the areas around drains and pipes. Pay special attention to small cracks and holes in the basement. You can also buy a device that tests for radon gas. It will cost you about eighty dollars. You can get one from the Radiation Safety Institute of Canada.
For more information about radon gas and radiation safety, the Institution's website is a good source of information.