You can’t see it, smell it, or taste it—but radon could be accumulating in your home right now.
Most people associate radon testing with winter—but that’s a misconception. Radon gas can enter homes any time of year, especially in areas with naturally high concentrations in the soil. And many parts of Ontario fall squarely in that category.
If you haven’t tested yet, summer is just as good a time to start as any—and potentially more revealing than you’d expect.
What Is Radon?
Radon is a naturally occurring radioactive gas that forms when uranium breaks down in soil and rock. It’s colourless, odourless, and completely undetectable without specialized testing. Because it originates underground, it seeps into buildings through any opening at or below grade level.
Common entry points include:
- Cracks in the foundation
- Gaps around pipes or sump pumps
- Floor drains or unfinished basements
Once inside, radon can build up—particularly in enclosed, poorly ventilated spaces like basements, crawl spaces, and lower-level rooms.
The Health Risks of Radon Exposure
Radon is the second leading cause of lung cancer in Canada, after smoking. It’s responsible for approximately 3,200 lung cancer deaths in Canada each year—a number that rarely gets the public attention it deserves.
Long-term exposure to elevated radon levels increases your risk significantly, and children and non-smokers who spend more time at home are especially vulnerable. Because there are no immediate symptoms—no coughing, no irritation, no warning signs—many people don’t discover they’ve been exposed until serious damage has already been done.
The only way to know your radon levels is to test.
Why Summer Isn’t “Safe” from Radon
There’s a common assumption that radon is mainly a winter concern—that when you open windows and let fresh air in during summer, the problem goes away. Unfortunately, that’s not the full picture.
Several summer factors can actually contribute to elevated radon levels indoors:
- Air conditioning and closed windows can trap radon inside just as effectively as winter heating
- Dry summer soil around the foundation can still release significant amounts of radon gas
- Changed living patterns — basement offices, home gyms, or guest rooms used more in summer — can increase the amount of time people spend in the highest-radon areas of a home
Testing across different seasons also gives you a more complete and accurate picture of your true year-round average exposure—which is what matters most for long-term health.
How Radon Testing Works
Radon testing is more accessible than most people realize. There are two main approaches:
- Short-term tests (2–7 days) — provide a quick snapshot of current radon levels, useful as a starting point
- Long-term tests (90+ days) — recommended for the most accurate picture of your year-round average exposure
DIY test kits are affordable and easy to use—you place a small detector in the lowest livable area of your home, leave it for the required period, and mail it to a certified lab for analysis. Alternatively, a professional can handle the entire process, from placement to results and next steps.
If results come back above 200 Bq/m³—Health Canada’s action level—a radon mitigation system can reduce indoor levels dramatically, often by more than 80%. It’s one of the most effective and straightforward home health upgrades available.
When Did You Last Test?
If you’ve never tested your home for radon—or only did so years ago before any renovations or structural changes—it’s worth a fresh look. Radon levels can shift as homes settle, as landscaping changes, or as you begin using different parts of your home more regularly.
Radon doesn’t care what season it is. And protecting your home’s air quality starts with simply knowing what’s there.
Ready to find out? Learn more about radon testing and book a professional assessment with ISG.