What are the Canadian guide lines?
• Remedial measures be taken in a dwelling whenever the average annual radon concentration in the normal occupancy area exceeds 200 becquerels per cubic meter. • The higher the radon concentration, the sooner remedial measures should be taken. • When remedial action is taken, the radon level should be reduced to a value as low as practicable (i.e., reduced as much as possible using methods that are cost-effective). • The construction of new dwellings should employ techniques that will minimize radon entry and will facilitate post-construction radon removal, should this subsequently prove necessary.
