Radon gas is invisible, odourless and tasteless in water and air, and we are surrounded by it at all times. It is present in every breath you take, but in very small quantities. Radon becomes a health concern for humans when we are exposed to it in high concentrations, and modern housing practices provide a relatively airtight environment where we are exposed to much higher levels than in the leaky homes of the past.  

Radon gas is a by-product of decomposing uranium, and homes in all regions across the country are at risk.
Health Canada recommends any homeowners with concentrations exceeding 200 Bq / m3 should take action to safeguard interior air quality. Important to note; this threshold does not mean that there is no health risk below 200 Bq / m3. 

Health Canada conducted a nationwide survey of radon concentration in homes, which took place over two years and included 18,000 participants. Their conclusion was that 6.9% of Canadians live in homes where the radon concentration is greater than the maximum guideline of 200 Bq / m3.

The only way to know if a house has a high radon concentration is to have the air in your home tested, and there are two ways to go about that; you can purchase a do-it-yourself test kit online or perhaps through your local municipality, or you could contact a local radon-mitigation expert and have them conduct a test for you. Below are links to help you have your air tested, as well as techniques for radon prevention in new homes and mitigation techniques in existing homes that tested above safe levels.