Radon 101: What is it and how does it get into your home?

When it comes to indoor air quality, most homeowners think first about dust, mold, asbestos, but what about the invisible threats? One of the stealthiest is radon, a colourless, odourless, radioactive gas that can accumulate inside homes and buildings and quietly raise the risk of serious health problems.

What is radon and where does it come from?  

Radon is a naturally occurring radioactive gas produced as uranium or thorium decays in soil, and rocks. Because it’s inert, colourless and odourless, you won’t know it’s there without testing. Across Canada, radon is the leading cause of lung cancer in non-smokers, responsible for more than 3,000 deaths each year. Because of the region’s uranium-rich soil and tightly sealed homes built for cold climates, Saskatchewan and Alberta consistently record some of the highest radon levels in the country. According to Canadian data, radon is present in every building, and no region is radon-free. It’s worth noting that while radon is “natural”, natural does not always mean “safe”.

How does radon get into buildings?

Radon enters buildings primarily from the ground beneath them. The gas moves through soil and rock and finds its way into a building through cracks in floors, walls, construction joints, gaps around service pipes and sumps, or through the building materials themselves in rare cases.

Once inside, if the building is relatively sealed, poorly ventilated or has low‐level air exchange, radon can accumulate to elevated levels. Also, buildings with basements or crawlspaces, or those built on slabs with underlying soil, may be at higher risk. For Canada and colder climates, where homes are well sealed in winter, these levels rise significantly.

What are the health effects of radon?

As previously mentioned, radon is linked to lung cancer, especially in non-smokers. The risk is significantly higher for smokers or former smokers; when radon exposure and smoking combine, the risk multiplies. It’s crucial to understand that you won’t feel “symptoms” from radon exposure the way you might for a mold issue. The damage is cumulative, invisible, and unfolds over many years, similar to asbestos exposure.  

Why are radon levels higher in Saskatchewan and Alberta?

In provinces like Saskatchewan and Alberta, there are several factors that drive higher-than-average radon levels:

• Uranium-rich soils: Saskatchewan, in particular, is known for significant uranium deposits. For instance, the province accounts for 22 % of the world’s uranium production. Because radon is the product of uranium decay, higher uranium content in soil/rocks means higher radon potential.

• Building practices and climate: In places with cold winters (like much of the Prairies) houses are built and insulated to be tight, with fewer drafts and lower natural ventilation. This means radon that seeps in has fewer “escape routes”.

How can radon be mitigated or reduced?

The good news? Radon mitigation is well understood and very doable. Here are some common approaches:

• Sub-slab depressurization: Is one of the most effective methods and consists of a system that draws radon from beneath the slab or foundation and vents it safely above the roofline.

• Sealing and blocking entry points: Sealing cracks, service openings, sump pits, gaps can reduce the influx of radon. While not always sufficient on its own, it helps in conjunction with ventilation or active systems.

• Improving ventilation: Increasing fresh air exchange, especially in basements or low-lying rooms, can reduce radon concentrations.

• Testing after mitigation: Once mitigation systems are in place, retesting is essential to ensure they’re working properly and radon levels are safely reduced.  

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What else do you need to know about radon?

If you’ve never tested your home or building for radon before, now’s the time to start, especially during the colder months when windows and doors stay closed. Here are a few key things to know before you begin:

• Long-Term testing: Since radon levels naturally fluctuate as seasons change and temperatures rise and fall, it is recommended to test for at least 91 days (or three months). A long-term test averages out variables (such as humidity, temperature, and ventilation), giving you a more accurate reading of the air you breathe most of the year.

• When to test: For the most accurate results, radon testing should be done during the winter months as that’s when homes are sealed up to conserve heat, resulting in any radon accumulating to give you a truer picture of the problem.  

• Re-testing: Radon levels can change over time due to foundation shifts, renovations, HVAC updates, or even changes in nearby construction. It’s a good idea to retest every two to five years, or sooner if you’ve recently remodeled, added a basement suite, or altered your home’s ventilation. If you had a radon problem in the past and it was mitigated, it’s best to retest the following heating season (when your furnace gets turned back on) to confirm the problem is gone.  

• Where to test and where not to: Radon testing should be done in the lowest lived in level of a building/home, which is typically the basement. Avoid kitchens, bathrooms, laundry rooms, or furnace rooms, since humidity and fluctuating airflow can affect results. Don’t place the test in direct sunlight, on floors, or right beside vents or exterior doors as this can also influence results.

At got mold?™, we know that a safe home starts with the air you breathe. Beyond more known issues like mold and asbestos, radon is one of the most overlooked risks to indoor air quality, even in areas where levels are naturally higher like Saskatchewan and Alberta.

By testing your space, sharing information with others, and working with qualified professionals, you’re helping to build a healthier environment for everyone who lives and breathes there.

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