Radon Levels in the Fraser Valley: What Homeowners Need to Know

The Fraser Valley — encompassing Abbotsford, Chilliwack, Langley, Mission, Hope, and surrounding communities — has a varied radon profile. Some areas carry elevated risk while others sit lower on average, but Health Canada’s advice is clear: every home should test regardless of location. Averages tell you about a region, not your house.

Radon Risk by Community in the Fraser Valley

The BC Centre for Disease Control maintains radon data for communities across BC. In the Fraser Valley, the pattern breaks down roughly as follows.

Chilliwack and Hope are the highest-risk communities in the region. Both sit closer to BC Interior geology — a transition zone where granite-bearing bedrock releases more radon than the marine sediments of the Lower Mainland coast. A higher proportion of homes in these communities exceed Health Canada’s 200 Bq/m³ action level compared to communities further west. If your home is in Chilliwack or Hope, testing is especially urgent.

Abbotsford shows moderate risk, consistent with the broader Fraser Valley pattern. The variety in Abbotsford’s housing stock matters here. Older homes in Clearbrook and Matsqui, built before radon-resistant construction existed, carry more risk than newer slab builds further east. Moderate city-wide risk still produces individual homes with high readings — averages are not ceilings.

Mission shares a similar risk profile to Abbotsford, with a mix of older and newer housing. Homes with full basements along the Fraser River benchlands are worth prioritizing for testing given their greater soil contact and older construction dates.

Langley and Maple Ridge generally trend lower than the eastern Fraser Valley communities, but exceptions are common. Geology varies block-to-block — particularly in older agricultural areas of the Langley City core and along the riverside benchlands in Maple Ridge. Lower average risk does not mean zero risk.

White Rock and Aldergrove sit at the lower end of the regional risk range, influenced by coastal geography and predominantly marine sediment soils. Neither is risk-free, but the baseline is lower than in communities closer to the Interior transition zone.

Which Homes Are Most at Risk?

Regardless of community, certain home characteristics increase radon exposure:

• Homes built before 2000 were not required to include radon mitigation features. Most pre-2000 homes in BC have no radon rough-in or soil gas barrier.
• Homes with full basements have the most soil contact. Basements are typically at the lowest air pressure in the home, which pulls radon upward from the ground.
• Crawlspace homes, especially those with exposed soil rather than a concrete floor, can have high concentrations — soil gases rise freely without a slab barrier.
• Slab-on-grade homes are not immune. Radon enters through cracks, pipe penetrations, and the junction where the slab meets the wall.

Foundation type alone doesn’t determine risk. An older Langley City home on a crawlspace can exceed 200 Bq/m³, while a Chilliwack basement can test below 100 Bq/m³. The only reliable answer is a test.

When to Test — and How

Test during the heating season: October through April. In BC’s climate, homes are sealed for much of this period — windows closed, fresh air exchange reduced. Radon accumulates faster and reaches higher concentrations than in summer when homes are regularly ventilated.

For an accurate result, BC Radon Control uses long-term alpha track tests placed for 91 days or more. This is the method required by C-NRPP standards, accepted by Health Canada, and recognized for real estate transactions. Short-term tests (under 7 days) can serve real estate transactions when time is limited, but a long-term test gives a more accurate picture of annual average exposure.

Learn about BC Radon Control’s certified testing services →

Understanding Your Results

Once you receive your radon test report, here is how to read the number:

Result	Health Canada Guidance	Recommended Action
Under 100 Bq/m³	Below reference level	No action needed. Retest in 2–5 years.
100–200 Bq/m³	Elevated but below action level	Consider mitigation, especially with children in the home.
200–600 Bq/m³	Above action level	Mitigation recommended within 2 years.
Over 600 Bq/m³	Significantly elevated	Mitigation recommended within 1 year.

What to Do If Your Result Is Above 200 Bq/m³

Sub-slab depressurization is the standard mitigation method used by certified contractors in BC. A C-NRPP technician drills through the foundation slab, installs a vent pipe routed to the exterior, and connects a low-power fan that draws radon out from beneath the home before it can enter the living space.

BC Radon Control installs mitigation systems in a single day throughout the Fraser Valley — Abbotsford, Chilliwack, Langley, Mission, Hope, Maple Ridge, Aldergrove, and White Rock. Every installation is guaranteed to reduce radon below 200 Bq/m³ and includes a one-year labour warranty and five-year fan warranty.

Learn more about the mitigation process →

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Ready to test your Fraser Valley home? BC Radon Control offers free quotes for certified radon testing and mitigation across the region. Contact us →