Radon in New Brunswick Homes: What Every Owner Should Know

What is radon?

Radon is a naturally occurring radioactive gas produced when uranium in soil and bedrock breaks down over time. It is invisible, odourless, and tasteless, which means nothing about a home's age, condition, or location can tell you how much radon is inside it. The only way to know is to test.

Outdoors, radon disperses into the atmosphere and is quickly diluted to very low concentrations. Indoors is a different story. Because a house sits directly on or in the ground, soil gas can seep in and accumulate, particularly in basements and lower levels where air exchange is limited. Concentrations indoors can build to levels many times higher than outdoor air without anyone noticing.

The health context matters. According to Health Canada, radon is the second-leading cause of lung cancer after smoking. The risk comes from long-term exposure — breathing elevated radon levels over many years — not from brief contact. That is worth taking seriously, but it is also worth keeping in perspective: radon is one of the few household hazards that can be measured accurately and fixed reliably, usually in a single day of work.

Why New Brunswick is a higher-radon region

Radon potential is driven largely by geology, and New Brunswick's geology works against us. Much of the province sits on uranium-bearing bedrock — granites, shales, and other formations that naturally release radon as their minerals decay. Combined with soils that allow soil gas to move freely toward foundations, this places New Brunswick among the higher-radon regions in Canada.

That said, geology only sets the stage. Radon levels vary enormously from one house to the next, even between neighbouring properties on the same street. The amount of radon in a particular home depends on the soil directly beneath it, how the foundation was built, how airtight the lower level is, and how the house is heated and ventilated. Two similar homes side by side can test at very different levels.

The practical consequence is simple: you cannot rely on a neighbour's test result, a regional map, or the age of your home to judge your own risk. Every home in the Fredericton, Oromocto, and New Maryland area — old or new, with or without a basement — should be tested at least once.

How radon gets into a home

Radon moves through the ground as a gas and enters buildings because of air-pressure differences. During the heating season, warm air rising through the house creates a slight vacuum in the lower levels — often called the stack effect — which actively draws soil gas indoors through any available opening. Common entry points include:

• Cracks in foundation walls and floor slabs, including hairline cracks that seem too small to matter.
• The floor-wall joint, where the concrete slab meets the foundation wall.
• Sump pits without sealed, gasketed lids.
• Floor drains and other openings in the slab.
• Gaps around service penetrations, such as water lines, sewer pipes, and electrical conduits.
• Exposed soil in crawlspaces or unfinished areas.

Many of these openings are the same pathways that let ground moisture into a basement, which is why radon sealing and moisture control often go hand in hand. If your lower level shows signs of dampness as well, our guide to basement moisture and mold is a useful companion to this article.

Testing: the only way to know your number

Health Canada's guideline for radon in indoor air is 200 becquerels per cubic metre (Bq/m³), measured as an annual average. If a long-term test shows your home above that level, Health Canada recommends taking action to reduce it — and the higher the level, the sooner that should happen.

Because radon concentrations swing from day to day and season to season, a long-term test of at least 91 days is the preferred way to measure. A short snapshot taken during a low period can offer false reassurance, while one taken during a spike can cause unnecessary alarm. Winter is the best season to test: windows and doors stay closed, the heating system is running, and levels are typically at their highest, giving you a realistic picture of your exposure.

Testing is inexpensive and simple. You can buy a do-it-yourself long-term test kit from many hardware stores, online retailers, or lung-health organizations. Place the detector in the lowest level of the home where people spend several hours a day, leave it undisturbed for the full test period, then mail it to the laboratory for analysis. If you would rather not handle it yourself, a measurement professional certified under the Canadian National Radon Proficiency Program (C-NRPP) can carry out the testing for you.

What to do if your levels are high

An elevated result is not an emergency, but it is a clear signal to act. The good news is that radon mitigation is a mature, well-proven trade with predictable results.

The most common and most effective fix is a system called sub-slab depressurization. A mitigation contractor drills a small opening through the basement slab, inserts a pipe, and connects it to a quiet, continuously running fan that vents above the roofline or at an approved exterior location. The system reverses the pressure balance beneath the slab so that soil gas is collected and exhausted outdoors before it can enter the house. Most installations are completed in a day and reduce indoor radon levels dramatically.

Sealing entry points — foundation cracks, sump lids, floor drains, and gaps around penetrations — supports the system and improves its efficiency, but sealing alone is rarely enough to fix a genuine radon problem. For any mitigation work, we recommend hiring a professional certified through C-NRPP, the same national program that certifies measurement providers. After installation, run another long-term test to confirm the system is performing, and retest every few years or after any major renovation.

Radon and real estate transactions

Radon comes up more and more often when homes change hands, and for good reason: a buyer is committing to the air their family will breathe for years. The challenge is timing. A proper long-term test takes at least 91 days, which rarely fits within a typical purchase timeline.

There are practical ways to handle this. Sellers can run a long-term test before listing and share the results — a low reading is a genuine selling feature, and a mitigated home with documentation shows the issue has been handled responsibly. Buyers who cannot get a long-term result before closing can plan to test during their first winter in the home, knowing that mitigation is straightforward if the number comes back high. Some parties negotiate based on a short-term screening test with an agreement to follow up with long-term confirmation.

During a residential property inspection, we can point out conditions relevant to radon — an unsealed sump pit, slab cracks, exposed soil in a crawlspace, or an existing mitigation system — although only a test can measure the actual level. If you are buying or selling in the greater Fredericton area and want to talk through your options, get in touch with us.

Key takeaways

Radon is a manageable risk, but only if you measure it. Here is what we want every New Brunswick homeowner to remember:

• Radon is an invisible, odourless radioactive gas that comes from soil and bedrock, and New Brunswick is among the higher-radon regions in Canada.
• Health Canada identifies radon as the second-leading cause of lung cancer after smoking, and its guideline for indoor air is 200 Bq/m³.
• Levels vary house to house — a neighbour's result tells you nothing about your own home.
• A long-term test of at least 91 days, ideally over winter, is the most reliable way to measure.
• Sub-slab depressurization installed by a C-NRPP certified professional is the standard, effective fix, supported by sealing entry points.
• If you are buying or selling, plan for radon early — test before listing, or budget to test soon after moving in.