What Is Radon?
Radon is a naturally occurring radioactive gas that forms from the breakdown of uranium in soil and rock. It is invisible, odourless, and tasteless, which means the only way to know how much is in your home is to test.
Radon is widely recognized as a major health risk indoors. According to Health Canada and other leading health authorities like the EPA and the WHO, long-term exposure to elevated radon is the number one cause of lung cancer in non-smokers and a leading cause overall.
Radon gas breaks down into radioactive particles that can be inhaled into the lungs. Over time, this exposure can damage lung tissue and increase the risk of lung cancer. The risk is much higher for people who smoke because radon and smoking together amplify risk.
How Radon Gets Into Your Home
Radon originates in the ground. Homes can draw in “soil gas” when indoor air pressure is lower than the pressure in the soil around and beneath the foundation. That pressure difference pulls gases upward into the building through openings where the home contacts the ground.
A helpful way to think about it is this: most radon issues are connected to what’s happening under and directly around the foundation. Radon often enters through pathways on the lowest level, including slab openings and below-grade joints.
Common Entry Points
It’s true that homeowners often focus on visible wall cracks, but radon entry is mainly about any opening connected to the soil. In many homes, radon pathways are most significant at the basement floor/slab level, joints, sump areas, and utility penetrations.
Health Canada lists typical entry routes as:
Cracks or flaws in floor slabs and foundation walls, floor/wall joints, exposed soil in crawlspaces, gaps around utility penetrations and support posts, floor drains, and sumps.
A practical note on sealing: sealing cracks can be a worthwhile step for general air leakage and moisture control, but on its own it rarely solves a radon problem because there are often multiple entry pathways. If radon levels are high, the most reliable fix is usually a mitigation system that gives soil gas a better path to the outdoors (instead of into the home).
Does My Home Require Testing?
Health Canada recommends that every homeowner test because radon can be present in any home, regardless of age, style, or how well it’s maintained and because you can’t detect it without a test.
Local context matters too. A large Canadian dataset (including Prairie regions) has found a meaningful portion of homes testing above Health Canada’s guideline, and many more above the World Health Organization’s suggested reference level.
You can explore Canadian results (including Calgary-area context) via the Cross Canada Radon Survey.
How Radon Testing Is Conducted
The best overall approach is long-term testing because radon fluctuates from day to day and season to season. Since radon is a long-term health risk, what matters most is the long-term average.
Step 1: Choose the right type of test
Long-term test (recommended): 91 days to 12 months. This is Health Canada’s preferred method for an accurate home average.
Short-term test: 2 to 7 days. This can be useful for screening, but it’s less reliable and can sometimes create false reassurance or unnecessary worry if interpreted as “the final answer.”
Step 2: Use an accurate, recognized device
Whether you use a lab-based long-term kit or a consumer-grade digital monitor, accuracy matters. Health Canada and the Canadian radon community have warned that some consumer radon detectors sold online have been recalled due to inaccurate readings.
A practical consumer resource is the C-NRPP list of consumer-grade electronic radon monitors (including guidance on device performance).
Step 3: Place it correctly
In general, place the test on the lowest lived-in level of the home (often the basement), away from windows, exterior doors, floor drains, and heat sources. Follow the device instructions carefully so results aren’t skewed.
Understanding Radon Test Results
Health Canada’s guideline is 200 Bq/m³. If your long-term average is above that, Health Canada recommends taking action to lower radon levels within 1 year, and sooner if levels are higher.
Other commonly referenced guidelines include:
The World Health Organization suggests a national reference level of 100 Bq/m³ where possible, and that it should not exceed 300 Bq/m³.
The U.S. Environmental Protection Agency recommends fixing homes at or above 4 pCi/L (about 150 Bq/m³) and also suggests considering action between 2 and 4 pCi/L (about 75–150 Bq/m³).
Don’t Panic if Your Results Are High
Radon is a long-term risk, not an emergency. A high result doesn’t mean immediate danger over weeks or a couple of months. It means it’s wise to plan mitigation so your long-term exposure is reduced.
The good news: radon is fixable. Most homes can be effectively mitigated with proven methods that redirect soil gas safely outdoors.
Optional Local Resource Note
If you’d like help with next steps, Health Canada recognizes C-NRPP certification for radon measurement and mitigation professionals in Canada. One Airdrie, Alberta based company listed through these channels is Radon Care. Their website is www.radoncare.ca
Disclosure: We do not receive compensation for referrals. This information is shared as an educational resource and homeowners can choose any qualified provider.
For more info: Health Canada radon information and guidance: https://www.canada.ca/en/health-canada/services/health-risks-safety/radiation/radon.html
