Radon questions, answered

From the natural breakdown of uranium in soil and rock, which exists in varying amounts nearly everywhere. Uranium decays through several steps into radium and then radon gas, which moves through the soil and escapes into the air.

Through any opening in contact with the ground: cracks in the slab or foundation walls, construction joints, gaps around pipes and wires, floor drains, sump pits and crawl spaces. A heated house in winter acts like a chimney, pulling soil gas in at the bottom.

No. Radon is colourless, odourless and tasteless, and Health Canada describes its health risk as long-term, not immediate. The only way to find out how much is in your home is to measure it.

Yes. A University of Calgary-led study published in 2017 found about 1 in 8 homes tested in Calgary and area at or above Health Canada's guideline, and later research shows newer homes trending higher. Our page on whether radon is a problem in Calgary summarizes the research.

No. Research from the University of Calgary found that radon in newly built Canadian homes has been increasing since around 1980, and new homes in Canada average far more radon than new homes in Sweden. Age doesn't predict your level; a test does.

Yes. Slab-on-grade homes, crawl spaces and even ground-floor apartments can have elevated radon, because any floor in contact with soil can let it in. Levels are often highest in basements simply because they have the most contact with the ground.

Radon can dissolve in groundwater, so homes on private wells can have radon in the water that's released into the air during showers and laundry. Municipal systems supplied by rivers typically carry little. If you're on a well, see our guide to radon in well water.

It can lower levels temporarily, especially on the lowest floor, but it isn't practical in a Calgary winter, wastes heat and stops working the moment windows close. Health Canada lists increased ventilation as having limited effect on its own; a mitigation system is the reliable fix.

Individual radon atoms decay, with a half-life of about 3.8 days, but the soil keeps producing more, so a home with a radon problem stays that way unless something changes how soil gas enters. Levels rise and fall with seasons and weather; they don't trend to zero.

Yes. A long-term kit from a reputable laboratory, placed correctly on the lowest lived-in level for at least 91 days, gives a valid result. Follow the instructions exactly, record the dates and mail it promptly. Our step-by-step testing guide covers each detail.

You can buy a long-term kit, use a program that provides kits when one is running, or hire a C-NRPP certified measurement professional. Our guide to getting radon tested in Alberta compares the three routes, with costs and timelines.

Yes. Health Canada notes that smoking and radon exposure together raise lung cancer risk far more than either alone. For smokers and former smokers, reducing a high radon level matters even more.

Health Canada lists lung cancer as the only known health effect of radon; it does not list headaches, coughs or fatigue. The risk is long-term, not immediate, and it builds with the level and the years of exposure. Our health guide explains what the evidence says.

Radon decays with a half-life of about 3.8 days, but it's constantly replaced from the soil as long as soil gas can enter. That's why the solution is to change the pressure under the house so that soil gas is vented outside, not to wait for radon to clear.