Have you tested for radon?

Radon is a naturally occurring gas that results from uranium breaking down underground. It gives off radiation and is odourless, colourless and tasteless. Remember your table of elements? Its symbol is Rn.
 
It’s found in homes across Canada and gets in through cracks in foundation walls, floor drains, or anywhere the house contacts the soil. 
 
It’s the second highest cause of lung cancer behind smoking and the number one cause in nonsmokers. This is especially important if you spend a lot of time in the basement, specifically in winter, as our homes are more air tight with all our windows closed.
 
You can buy a do-it-yourself test kit for about $30 and then ship it to a lab to analyze the results. Or you can hire a professional to test it for you (some even do free testing). You can also purchase a radon detector for about $200-300 and monitor it on an ongoing basis.  See  https://www.canada.ca/en/health-canada/services/radon.html for more information and links to where you can find a test kit or professional near you. Regardless of the method you choose, the test should last three months. 
 
The Canadian guideline is 200bq/m3. If it’s over this amount, you should take steps to remediate it. This can be done by venting the gas from under the basement floor to the outside.

For a more comprehensive guide check out Radon - A Guide For Canadian Homeowners.