What is radon?
Radon is a radioactive gas produced naturally as uranium in soil and rock breaks down.
Outdoors, radon is usually diluted to low levels. Indoors, it can build up—especially in lower parts of a home that are in contact with the ground. You cannot see, smell or taste it, so its presence is not a sign of poor housekeeping and cannot be detected by your senses.
How does radon enter a home?
Radon-containing soil gas can be drawn through openings where the home meets the ground.
Air pressure inside a home is often slightly lower than the pressure in the soil around the foundation. That difference can draw soil gas indoors through foundation cracks, construction joints, sump pits, floor drains, gaps around pipes and other openings.
New, old, finished and unfinished homes can all have radon. Foundation details, soil conditions, ventilation and how the home operates all affect the level—which is why one house cannot predict the result next door.
Should I be concerned?
Radon is a legitimate long-term health concern, not an immediate emergency.
Long-term exposure increases the risk of lung cancer. Health Canada identifies radon as the leading cause of lung cancer in people who do not smoke, and the risk is higher for people who smoke or have smoked.
The practical response is to measure calmly and act on a valid result. Knowing the level lets you decide whether any reduction work is needed.
What do radon levels mean?
Canada’s guideline is 200 becquerels per cubic metre (Bq/m³), measured as a long-term average.
Health Canada recommends taking action to reduce radon when a long-term result is above 200 Bq/m³. Below the guideline does not mean zero risk; in general, the lower the long-term level, the better.
Hourly and daily readings can move up and down. Decisions should be based on the average from a properly placed long-term test rather than a single short-term spike.
How do I know the level in my home?
Testing is the only way to know.
Health Canada recommends measuring for at least 91 days, ideally during the heating season, on the lowest level where someone normally spends time. A long-term test smooths out normal day-to-day and seasonal changes.
A neighbour’s result, the age of the house and a regional map cannot replace a test in your own home.
What if the result is elevated?
Radon levels can usually be reduced effectively.
A C-NRPP-certified mitigation professional can assess how radon is entering and design a system for the foundation. The most common approach draws soil gas from beneath the home and vents it safely outdoors, then a post-mitigation test confirms the result.