Lambton
Radon testing and mitigation in Sarnia, Ontario
Sarnia sits where Lake Huron drains into the St. Clair River, across from Port Huron, Michigan. Here’s what’s known about radon in Sarnia, and how to find out about your home.
- Region
- Lambton
- Population
- about 72,000
- Public health
- Lambton Public Health
- Local factors
- 5 reasons to test
Is radon a problem in Sarnia?
Radon can exceed Health Canada’s 200 Bq/m³ guideline in any Sarnia home. Health Canada survey data tabulated by Cancer Care Ontario put Lambton at 8.4% of homes at or above the guideline. Across Ontario, about 1 in 8 homes tested at or above the guideline in the 2024 national survey. Locally, nearby uranium-bearing shale, cracking clay soils and converted cottages and crawlspaces are reasons to test. A 91-day test is the only way to know your home’s level.
Radon in Sarnia
Sarnia sits where Lake Huron drains into the St. Clair River, across from Port Huron, Michigan. In the Health Canada survey data that Cancer Care Ontario tabulated by public health unit, 8.4% of the homes tested in Lambton County were at or above Health Canada’s 200 Bq/m³ guideline. That is the county figure and not a Sarnia-only one, and it sits alongside a geology story that makes this part of Ontario worth taking seriously.
The ground under Sarnia
Sarnia is built on glacial clay plain and moraine ridges, with sandy beach and dune deposits toward Lake Huron. Underneath, the bedrock includes the Kettle Point Formation, a black shale that Ontario Geological Survey drill core puts at over 30 ppm uranium on average, roughly ten times a typical rock. It crops out on the lakeshore at Kettle Point and lies beneath a cover of glacial deposits across Lambton, so how much it matters varies from house to house.
Sarnia’s homes
Sarnia grew with the petrochemical industry, and much of its housing is post-war: bungalows and storey-and-a-half homes whose basements have been finished over the decades. Bright’s Grove and the Lake Huron shore mix older cottages with newer year-round homes. Rural Lambton is farmhouses and acreage properties, mostly on private wells.
What the data says
Of homes tested in the Lambton health unit area were at or above 200 Bq/m³ in the Health Canada survey data tabulated by Cancer Care Ontario (2009 to 2013).Source: Cancer Care Ontario — Risk of Residential Radon Exposure Varies Geographically (results by public health unit, Health Canada survey data 2009–2013)
Ontario homes at or above Health Canada’s 200 Bq/m³ guideline in the 2024 Cross-Canada Survey, more than double the share found a decade earlier.Source: Cross-Canada Survey of Radon Exposure in the Residential Buildings of Urban and Rural Communities (2024)
Higher average radon exposure for rural residents than urban residents in a 2024 national study of 42,051 homes, mostly linked to drilled wells.Source: Goodarzi et al., Scientific Reports (2024) — rural communities and drilled-well annuli
Local results
Building a real radon picture for Sarnia
Public radon data for Southern Ontario towns is thin. The national surveys tested only a handful of homes per area. So we’re building our own: anonymized long-term results from homes we test, published by area once there are at least 30, so no single home can be identified and small samples can’t mislead.
Sarnia: collecting results. Already tested? Check your number and share it anonymously when you book.
Local factors
What can push radon up in Sarnia
Not a prediction for any single home, just the reasons a test is worth it here.
Uranium-bearing shale nearby
Black shale is the most common uranium source rock in southern Ontario. The Kettle Point shale that runs under Lambton and western Middlesex and Elgin averages over 30 ppm uranium in Ontario Geological Survey drill core, roughly ten times a typical rock.
Clay plains
Dense clay slows soil gas, but it cracks in dry spells. Gas then follows the easiest route: the gravel backfill, weeping tile and utility trenches that lead straight to a basement.
Cottages and crawlspaces
Lakeshore cottages converted to year-round homes often sit on crawlspaces, piers or patched slabs. Once winterized and heated, they can start pulling in soil gas they never did as summer places.
Rural homes on drilled wells
A 2024 national study of over 42,000 homes found rural residents were exposed to about 30% more radon than urban residents, with most of the gap linked to drilled wells. Researchers suspect gas travels up the gap around the well casing.
Century homes
Fieldstone, rubble and early concrete foundations, earth-floor cellars and open sumps give radon many ways in. Older doesn’t mean safer: these homes still need a test.
Where we work
Sarnia neighbourhoods and nearby communities
- Downtown Sarnia
- Point Edward
- Bright’s Grove
- Sarnia North
- Corunna
- Mooretown
- Courtright
- Petrolia
- Forest
- Kettle Point
- Grand Bend
- Port Franks
Nearby: Radon in Strathroy · Radon in Chatham · Radon in Goderich
How it works
From test to fix
- Book
Tell us about your Sarnia home. We reply within one business day.
- Test for 91+ days
A certified technician places long-term detectors on your lowest lived-in floor. You get an early reading at 2 weeks.
- Get your result
Lab-verified average, explained against Health Canada’s guideline.
- Fix it if it’s high
A sub-slab system designed for your foundation, at a fixed price, with results guaranteed.
Questions
Radon in Sarnia: FAQ
Is radon a problem in Sarnia?
Radon can exceed Health Canada’s 200 Bq/m³ guideline in any Sarnia home. Health Canada survey data tabulated by Cancer Care Ontario put Lambton at 8.4% of homes at or above the guideline. Across Ontario, about 1 in 8 homes tested at or above the guideline in the 2024 national survey. Locally, nearby uranium-bearing shale, cracking clay soils and converted cottages and crawlspaces are reasons to test. A 91-day test is the only way to know your home’s level.
Is there uranium under Sarnia and Lambton County?
The Kettle Point Formation, a black shale that Ontario Geological Survey core samples measured at over 30 ppm uranium on average, runs beneath Lambton under thick glacial deposits. How much that matters at a given house varies a lot. Testing tells you what actually reaches your basement.
Do you serve Grand Bend, Petrolia and the Lake Huron shore?
Yes. We test and mitigate across Lambton County, including Point Edward, Bright’s Grove, Corunna, Petrolia, Forest, Kettle Point, Port Franks and Grand Bend.
Do you offer radon testing and mitigation in Sarnia?
Yes. We test and mitigate homes throughout Sarnia, including Downtown Sarnia, Point Edward, Bright’s Grove, Sarnia North, Corunna and nearby. Call (226) 271-4667 or book online.
Radon is fixable. First, know your number.
Serving Sarnia, Strathroy, Chatham and Goderich.