What are the current radon levels in different regions of New Brunswick and which areas are highest risk for basements?

New Brunswick has some of the highest radon levels in Canada, and every homeowner finishing a basement should test before starting any renovation work. Radon is a naturally occurring radioactive gas that seeps up through soil and rock into below-grade spaces, and NB's geology creates elevated risk across much of the province.

Health Canada's action level is 200 Bq/m3 (becquerels per cubic metre). Above this threshold, mitigation is recommended. Across New Brunswick, surveys have consistently shown that a significant percentage of homes exceed this guideline, making NB one of the higher-risk provinces nationally.

Regional Risk Levels

The Fredericton area and the upper Saint John River valley consistently show some of the highest radon readings in the province. The underlying granite and metamorphic bedrock in this region produces elevated levels of uranium decay, which generates radon gas. Homes in the Fredericton, Oromocto, and Woodstock corridors frequently test above 200 Bq/m3, with some readings exceeding 600 Bq/m3 or higher.

The Saint John area also shows elevated radon levels, though the readings tend to be somewhat lower on average than the Fredericton region. However, Saint John's heavy clay soils can trap radon gas near foundations, and the combination of older concrete block foundations with poor sealing means the gas has easy entry points into basements.

The Moncton area generally has moderate radon levels compared to Fredericton, but pockets of elevated readings exist throughout the Tri-Community (Moncton, Dieppe, Riverview). The sandy and silty soils in the Moncton region allow radon to migrate more easily through the ground, so even homes with newer poured concrete foundations can show concerning levels.

Northern New Brunswick (Bathurst, Miramichi, Edmundston) shows variable readings depending on local geology. Areas with more granitic bedrock tend to have higher levels, while areas with sedimentary rock tend to be lower. The rocky and glacial till soils common in northern NB can create unpredictable radon pathways.

Coastal areas like Shediac and the Acadian Peninsula generally show lower average readings, but individual homes can still exceed the guideline.

The critical point is that radon levels vary house by house, not just region by region. Two homes on the same street can have dramatically different readings based on foundation type, soil conditions, and how well the slab is sealed. This is why testing your specific home is essential.

Testing is simple and inexpensive. A long-term passive test kit costs $30 to $50 and sits in your basement for 3 months during the heating season (October through March is ideal). Professional short-term testing runs $150 to $300 and gives faster results. If your levels exceed 200 Bq/m3, a sub-slab depressurization system costs $2,000 to $4,000 to install. This system creates negative pressure beneath your basement slab, drawing radon gas out through a pipe and venting it above the roofline.

The key timing issue is that radon mitigation is far easier and cheaper to install before finishing your basement than after. Once walls are framed, insulated, and drywalled, and flooring is laid over the slab, retrofitting a mitigation system means cutting through finished surfaces. Test first, mitigate if needed, then finish. New Brunswick Basements can help you find contractors experienced with radon-aware basement renovations.

---

Looking for experienced contractors? The New Brunswick Construction Network connects homeowners with qualified professionals:

• Gionetterenovations
• Thirty Four Renovations