Understanding Radon and Its Risks Radon is a naturally occurring radioactive gas that can seep into homes through cracks in the foundation, gaps around pipes, and other openings. It is odorless, colorless, and tasteless, making it undetectable without proper testing. The primary health risk associated with radon exposure is lung cancer. Prolonged exposure to high levels of radon can significantly increase the risk of developing lung cancer, especially for smokers.

Canadian Guidelines for Radon in Residential Dwellings According to the Government of Canada, the current guideline for radon levels in indoor air for residential dwellings is 200 becquerels per cubic metre (200 Bq/m³). This guideline provides a threshold for when remedial action should be taken to reduce radon levels in homes.

Long-Term Radon Measurements & Importance of Long-Term Testin Radon levels can fluctuate significantly over short periods. Variations by a factor of 2 to 3 within a single day and even larger seasonal changes are common. Therefore, long-term measurements, typically lasting between 3 to 12 months, are recommended for an accurate assessment of annual average radon levels. Winter months often show higher radon levels due to homes being sealed against the cold.

Health Canada Recommendations Health Canada advises that radon tests in homes should be long-term measurements conducted during the heating season. Short-term tests of less than 1 month are not recommended as they do not provide a reliable indication of radon levels. A minimum testing duration of 3 months is ideal.

Short-Term Radon Measurements & Limitations of Short-Term Testing Short-term radon measurements are not considered reliable for assessing the need for remedial action. Because radon levels can vary greatly, any short-term test results should be followed up with a long-term test at the same location to make informed decisions about mitigation.

Confirmation with Long-Term Testing Short-term test results must be confirmed with a long-term test to ensure accuracy. This approach helps to account for daily and seasonal fluctuations in radon levels.

Measurement Strategy for Homeowners & Recommended Testing Practices

Health Canada recommends that every homeowner test their home for radon using at least one long-term detector for a minimum of 3 months, ideally during the heating season from October to April. This period tends to have the highest indoor radon levels due to closed windows and increased thermal stack effect.

Considerations for New Homes and Renovations For newly constructed homes, radon measurements should be taken during the first heating season after occupancy. Additionally, homeowners should re-test their homes whenever major renovations are conducted that might alter ventilation or airflow, as these changes can affect radon levels.

Testing in Warm Weather Radon measurements in homes without central air conditioning during warm weather may be misleading due to open windows. Extending the duration of the test can help mitigate this issue, reinforcing the importance of long-term measurements.

Our sellers, based on the above, I recommend not to remediate the radon results based on the comprehensive guidelines provided by Health Canada. The variability in radon levels and the recommendations for long-term testing support this decision. We encourage potential buyers to conduct their own long-term radon tests to obtain an accurate assessment of radon levels in the home.