Key Takeaways
- Radon is a radioactive gas that seeps in from the soil — invisible, odourless, and the #2 cause of lung cancer in Canada.
- Nova Scotia has elevated radon risk in many areas due to granite geology.
- Testing is easy and inexpensive (~$30–$60 mail-in kit); Health Canada’s action level is 200 Bq/m³.
- Mitigation (sub-slab depressurization) runs $1,500–$3,000 and is highly effective.
You can't see radon. You can't smell it. You can't taste it. It enters your home silently through cracks in the foundation, gaps around pipes, and through the soil beneath a crawlspace. And yet the Nova Scotia Lung Association estimates it kills around 120 Nova Scotians from lung cancer every year.
This isn't a fringe concern. Radon is the second-leading cause of lung cancer in Canada, after smoking. And Nova Scotia has some of the highest measured radon levels in the country, largely due to the province's granite-rich geology.
What is radon?
Radon is a naturally occurring radioactive gas produced when uranium in soil, rock, and water breaks down. Outdoors, it disperses instantly into the atmosphere and poses no health risk. In an enclosed space — a basement, a crawlspace, a tightly sealed house — it can accumulate to concentrations that significantly increase cancer risk with long-term exposure.
When radon is inhaled, it decays and releases alpha particles inside the lung tissue. These particles damage lung cells. When damaged cells replicate, cancer can develop. The risk increases with both the concentration of radon and the length of exposure. Health Canada's guideline is a maximum of 200 Bq/m³ (becquerels per cubic metre); mitigation is strongly recommended above that level.
Testing your home
Testing is the only way to know. You cannot estimate your radon level based on neighbourhood geology, home age, foundation type, or any other visible factor. A home with a poured concrete foundation can have high radon. A home with a block foundation can have low radon. The only way to know is to measure.
Long-term tests (90 days or more) are more accurate than short-term tests and are preferred. The most practical option for most homeowners is an alpha-track detector — a small passive device that you place in the lowest occupied area of the home and mail to a certified lab after the test period. Health Canada, the Nova Scotia Lung Association, and licensed measurement professionals can all provide guidance.
What to do if your levels are high
If your test comes back above 200 Bq/m³, mitigation is the answer — and it works. The most effective approach is active soil depressurization (ASD): a pipe is installed through the foundation slab or into the crawlspace, connected to a small fan that continuously draws radon-laden soil gas from beneath the home and vents it harmlessly outside. It's a well-established, highly effective technique that typically reduces radon levels by 80–99%.
Since 2010, the National Building Code of Canada has required new homes to include a rough-in for future radon mitigation and a vapour barrier to reduce radon entry. Older homes have no such protection and are more likely to have elevated levels.
The cost of not testing can be measured in something more than money. A test costs around $30–50 and takes three months. Mitigation, if needed, typically runs $1,500–3,000. Lung cancer costs considerably more.
Is your area at risk?
Nova Scotia has published an Interactive Radon Risk Map that shows measured radon levels across the province, overlaid on geological data. It’s a useful starting point — you can look up your municipality or neighbourhood and get a sense of whether your area has a history of elevated readings. That said, the map shows risk patterns, not your specific home. A house two doors down can have a completely different radon level than yours, depending on foundation type, soil conditions, and how tightly the building is sealed. The map is a reason to test, not a substitute for it.
Finding help in Nova Scotia
Health Canada maintains a directory of certified radon measurement and mitigation professionals. The Nova Scotia Lung Association is also a useful starting point for local resources. If you're buying a home, request a radon test as part of your home inspection process — a standard inspection doesn't include radon measurement, but it can be arranged concurrently.