London & Middlesex
Radon testing and mitigation in Dorchester & Thames Centre, Ontario
Thames Centre covers the country just east of London: Dorchester, Thorndale, Mossley, Putnam and the farmland between them. Here’s what’s known about radon in Dorchester, and how to find out about your home.
- Region
- London & Middlesex
- Population
- about 14,000 (Thames Centre)
- Public health
- Middlesex-London Health Unit
- Local factors
- 5 reasons to test
Is radon a problem in Dorchester?
Radon can exceed Health Canada’s 200 Bq/m³ guideline in any Dorchester home. No published local data rules any neighbourhood in or out. Across Ontario, about 1 in 8 homes tested at or above the guideline in the 2024 national survey. Locally, sandy or gravelly soils, Shield-derived glacial soils and rural drilled wells are reasons to test. A 91-day test is the only way to know your home’s level.
Radon in Dorchester
Thames Centre covers the country just east of London: Dorchester, Thorndale, Mossley, Putnam and the farmland between them. Dorchester in particular has added a lot of new family homes in the past decade.
The ground under Dorchester
The south branch of the Thames and its old meltwater channels left sand and gravel through much of the township, with till plain and moraine on the higher ground. It’s a classic southwestern Ontario mix: permeable valleys with glacial soils that carry Shield-derived uranium.
Dorchester’s homes
New subdivisions in Dorchester sit next to century farmhouses with stone foundations. Rural homes throughout Thames Centre rely on private wells. Both groups are worth a long-term test; they just tend to need different fixes when results are high.
What the data says
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)
Roughly how many homes per health region the first national survey (2009–2011) could test. Too few to clear any neighbourhood, which is why public maps can’t tell you about your house.Source: Health Canada — Cross-Canada Survey of Radon Concentrations in Homes, Final Report (2012)
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 Dorchester
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.
Dorchester: collecting results. Already tested? Check your number and share it anonymously when you book.
Local factors
What can push radon up in Dorchester
Not a prediction for any single home, just the reasons a test is worth it here.
Sandy or gravelly soils
Sand and gravel let soil gas move freely and over longer distances. More of the radon formed in the ground can reach the air around your foundation instead of decaying in place.
Glacial soils with Shield debris
The till and gravel left by glaciers here includes ground-up rock carried south from the Canadian Shield. Uranium travels with it, so radon can form close to your footings even where the bedrock itself is low in uranium.
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.
New, airtight construction
Canadian research shows newer homes have tended to test higher than older ones. Bigger, taller and tighter homes create a stronger stack effect that draws soil gas in through the slab.
Where we work
Dorchester neighbourhoods and nearby communities
- Dorchester
- Thorndale
- Mossley
- Putnam
Nearby: Radon in London · Radon in Ingersoll · Radon in St. Thomas
How it works
From test to fix
- Book
Tell us about your Dorchester 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 Dorchester: FAQ
Is radon a problem in Dorchester?
Radon can exceed Health Canada’s 200 Bq/m³ guideline in any Dorchester home. No published local data rules any neighbourhood in or out. Across Ontario, about 1 in 8 homes tested at or above the guideline in the 2024 national survey. Locally, sandy or gravelly soils, Shield-derived glacial soils and rural drilled wells are reasons to test. A 91-day test is the only way to know your home’s level.
How long does a radon test take in Dorchester?
A long-term test runs at least 91 days, ideally between October and April when windows are closed and radon is usually highest. Setup takes about 30 minutes. We retrieve the detector and send it to an accredited lab.
What does a radon system cost for a Thames Centre farmhouse?
Older farmhouses sometimes need extra sealing or a second suction point, especially with fieldstone walls or a partial earth-floor cellar. We quote after a site assessment. Most single-family systems in Ontario fall in the low-to-mid thousands of dollars.
Do you offer radon testing and mitigation in Dorchester?
Yes. We test and mitigate homes throughout Dorchester & Thames Centre, including Dorchester, Thorndale, Mossley, Putnam. Call (226) 271-4667 or book online.
Radon is fixable. First, know your number.
Serving Dorchester, London, Ingersoll and St. Thomas.