What Is Radon?

Where Radon Comes From

Radon isn't a pollutant that gets released by industry or traffic — it's a natural byproduct of rock and soil. Trace amounts of uranium-238 exist almost everywhere in the Earth's crust. Uranium decays extremely slowly, over billions of years, through a chain of radioactive elements. One link partway down that chain is radium-226, and when radium decays, it produces radon-222 — a gas.

Because radon is a gas rather than a solid, it isn't trapped in the rock the way its parent elements are. It moves freely through pore spaces, cracks, and groundwater, working its way up toward the surface. Some soil and rock types generate more of it than others — granite, shale, and phosphate deposits tend to have higher uranium content, so areas built on those materials generally test higher.

The Science: Why an Invisible Gas Can Hurt You

Radon-222 itself has a half-life of about 3.8 days — meaning half of any given amount decays away within that time. Most of the radon gas you breathe in is simply breathed back out before it decays. What actually causes the health risk isn't the gas passing through — it's what radon leaves behind.

When radon decays, it produces a series of solid, electrically charged radioactive particles known as radon progeny (or radon daughters) — polonium-218, lead-214, bismuth-214, and polonium-214. Unlike radon gas, these are solids. They attach themselves to dust and moisture in the air, get inhaled, and lodge in lung tissue. As they continue to decay, they release alpha particles directly into surrounding cells. Alpha particles are too weak to penetrate skin, but at point-blank range inside lung tissue, they can damage the DNA of the cells lining the airway — repeated damage over years is what raises lung cancer risk.

How Radon Gets Into Your Home

Radon from the soil surrounding and beneath your home is constantly trying to escape upward, and your house makes that easier than the undisturbed ground around it. Warm indoor air rises and leaks out through the upper levels of a house, which pulls in replacement air from wherever it can — including through the foundation. This is sometimes called the stack effect, and it acts like a gentle, constant vacuum that draws soil gas into the lowest levels of your home through:

• Cracks in foundation walls and floor slabs
• Gaps around plumbing, sump pits, and utility penetrations
• Construction joints where the foundation wall meets the floor
• Exposed soil in crawl spaces
• Dissolved radon released from well water during showering or washing (a much smaller contributor for most homes than soil gas)

This is also why radon concentrations are almost always highest in basements and lowest livable levels — they're physically closest to the source and most directly affected by the pressure difference pulling soil gas upward.

Why Radon Levels Change Over Time

Radon levels in the same home can vary significantly day to day and season to season, which is why Health Canada recommends long-term testing over at least 90 days rather than a single snapshot reading. Common causes of variation include:

• Season: levels are typically highest in winter, when homes are sealed up tightly and heating systems strengthen the stack effect
• Weather: barometric pressure drops (like before a storm) can pull more soil gas into a home
• Soil moisture: saturated or frozen ground can temporarily reduce soil gas flow, while dry, porous soil allows more
• How the home is used: open windows, running exhaust fans, and HVAC settings all change the pressure balance

How Radon Is Measured

Radon concentration is measured in becquerels per cubic metre (Bq/m³) in Canada, or picocuries per litre (pCi/L) in the United States. One pCi/L is roughly equal to 37 Bq/m³.

The Health Effects, Explained Accurately

Radon exposure does not cause any noticeable symptoms — no cough, no headache, no shortness of breath. That is precisely what makes it dangerous: there is no early warning system, and the only health effect is a statistically elevated risk of lung cancer that develops after years of exposure. Radon is the second leading cause of lung cancer overall (after smoking) and the leading cause among people who have never smoked.

Critically, radon and smoking don't just add together — they multiply. A smoker living in a home with elevated radon has a dramatically higher combined risk than you'd get from simply adding the risk of smoking to the risk of radon separately. This is one of the main reasons Health Canada recommends every home be tested, regardless of whether anyone in the household smokes.

Radon Geology in the Interior Okanagan

Radon potential depends heavily on the geology beneath a home. Much of British Columbia's southern interior, including the Interior Okanagan, sits on granitic and metamorphic bedrock formed as part of the region's mountain-building history — rock types generally associated with higher uranium content than the sedimentary or coastal rock found elsewhere in the province. That doesn't mean every home in the region has a problem, but it does mean local geology gives homeowners here more reason than average to test, rather than assume their home is fine.