Different homes, different counts
They tested different homes, and different numbers of them: 2,364 for the health unit, 100 to 199 for the survey.
How much radon is in Windsor-Essex homes?
The health unit tested 2,364 Windsor-Essex homes from 2015 to 2018. Of those, 11% had radon above Health Canada's guideline of 200 Bq/m³. Homes in the county outside the city ran about three times the city's rate: about 18% against about 6%.
A national survey found 14.5% at or above 200 Bq/m³ for the Windsor census metropolitan area, from a smaller and different set of homes. Both studies are below, with their sources. Only a test can tell you your own home's number.
2,364 homes
Tested by the health unit, 2015 to 2018
11%
of those homes tested above 200 Bq/m³
18% vs 6%
Essex County vs the City of Windsor, above 200 Bq/m³
14.5%
Windsor CMA homes at or above 200 Bq/m³, national survey
Sources: WECHU, Radon: Know Your Level 2015 to 2018 (opens in a new tab); home count from the WECHU February 2019 board resolution (opens in a new tab); 2024 Cross-Canada Survey of Radon (opens in a new tab), Table 1, p. 43, via the Canadian Radon Services Index (opens in a new tab); Health Canada (opens in a new tab).
What the health unit found, town by town
The Windsor-Essex County Health Unit (WECHU) ran its study over three winters, from 2015 to 2018. In all, 2,364 homes were tested.
The study tested detached and semi-detached homes. The person applying had to own the home. Each home was asked to test for at least 91 days on the lowest lived-in level.
In WECHU's figures, "Essex County" means the county outside the City of Windsor.
| Area | Above 200 Bq/m³ |
|---|---|
| Windsor-Essex, all homes tested | 11% |
| Essex County (outside the City of Windsor) | 17.9% |
| City of Windsor | 5.6% |
Source: WECHU, Radon: Know Your Level 2015 to 2018, p. 5 and Appendix D. The report's text rounds the county and city figures to 18% and 6%.
| Town | Average (Bq/m³) |
|---|---|
| Amherstburg | 119.8 |
| Kingsville | 118.7 |
| Leamington | 107.2 |
| Tecumseh | 105.6 |
| Essex | 98.2 |
| Lakeshore | 96.9 |
| LaSalle | 94.7 |
| City of Windsor | 86.4 |
| Windsor-Essex, all homes tested | 94.1 |
Source: WECHU, Radon: Know Your Level 2015 to 2018, Table 3, p. 12.
WECHU doesn't report a share above 200 for each town, so we don't show one.
The report flags one thing about its own numbers. Levels in year three came out 37% lower than in year two, and the report says where people put their kits may explain it.
Sources: WECHU, Radon: Know Your Level 2015 to 2018, pp. 5, 8 to 9, 18 and 20; home count from the February 2019 board resolution.
What the national survey found for the Windsor area
The 2024 Cross-Canada Survey of Radon also reports figures for Windsor. Its "Windsor" is the Windsor census metropolitan area: the City of Windsor plus Amherstburg, Essex, Kingsville, Lakeshore, LaSalle, Leamington and Tecumseh. That's all of Essex County except Pelee Island.
| Measure | Figure |
|---|---|
| Homes at or above 200 Bq/m³ | 14.5% |
| Homes from 100 to 199 Bq/m³ | 33.1% |
| Geometric mean (unweighted) | 99.3 Bq/m³ |
| Highest reading | 548 Bq/m³ |
| Homes in the sample | 100 to 199 |
Source: 2024 Cross-Canada Survey of Radon, Table 1, pp. 42 to 43, via the Canadian Radon Services Index. Area: Windsor census metropolitan area (Statistics Canada, 2021 Census (opens in a new tab)). Figures quoted as printed.
A geometric mean is a type of average used for radon, because readings can range widely (CRSI glossary (opens in a new tab)). The survey says it didn't have enough data to weight Windsor's figures, and that unweighted figures may move once they're weighted.
The survey used long-term tests of 90 days or more. Each one sat on the lowest floor where someone spends 4 or more hours a day. Its results cover houses (single-detached, semi-detached and row), not apartments.
The Windsor sample was small: 100 to 199 homes. Canada's figures in the same survey are weighted and Windsor's aren't, so we don't set them side by side.
Sources: 2024 Cross-Canada Survey of Radon, pp. 17, 22, 24 and 42 to 43, via the Canadian Radon Services Index.
Why the two studies give different numbers
Different areas
The areas differ. WECHU splits the City of Windsor from the rest of Essex County. The survey gives one figure for the Windsor census metropolitan area.
Different years
We can't line up the years. WECHU ran from 2015 to 2018. The survey doesn't say when Windsor's tests were done. Across Canada, 99.7% of its tests ran from 2009 to 2024.
Different ways of counting
And they count in different ways. The survey counts homes at or above 200 and includes row houses. WECHU counts homes above 200 and tested only detached and semi-detached homes.
That's why they don't land on the same number. We show both, with their sources.
Sources: 2024 Cross-Canada Survey of Radon, pp. 9 and 24, via the Canadian Radon Services Index; WECHU, Radon: Know Your Level 2015 to 2018.
What these numbers mean for your home
An area number is a share of homes. It can't tell you what's in yours. Health Canada says radon levels "will vary from one house to another, even if they are similar designs and next door to each other."
What your number means
For what a reading means, see what your radon number means.
Short or long test
For which test to use, see short and long radon tests.
Already got a high result?
Already holding a high number? Here's what to do with a high result.
The Canadian Radon Services Index has pages for Windsor (opens in a new tab) and Tecumseh (opens in a new tab). Each shows the 2024 survey result for the area, certified providers nearby and census housing numbers.
Essex County Library lends a digital radon monitor for up to 3 weeks, usually in the colder months. It's a short look, not a long-term test. We haven't confirmed whether City of Windsor residents can borrow one. More on radon test kits and library loans.
Sources: Health Canada, About radon (opens in a new tab); WECHU, Information about radon testing (opens in a new tab); Kingsville Times, October 2025 (opens in a new tab).
The only way to know your number is to test. See your testing options.
How many radon mitigation businesses have an office nearby?
Two, in the Canadian Radon Services Index data for census division 3537. That division is the City of Windsor plus all of Essex County. Windsor Radon is one of the two.
In the same data, 81.2% of people in the division live within 25 km of a certified radon mitigator's office.
This area is bigger than WECHU's "Essex County", which leaves out the city.
Source: Canadian Radon Services Index, Contractor Coverage (opens in a new tab), C-NRPP registry pull of 21 October 2026.
Where every number on this page comes from
- WECHU, Radon: Know Your Level 2015 to 2018, the report page and the report PDF it links. Checked 30 October 2026.
- WECHU February 2019 board resolution, for the 2,364 home count. Checked 30 October 2026.
- 2024 Cross-Canada Survey of Radon, the copy the Canadian Radon Services Index cites, Table 1, pp. 42 to 43. Checked 30 October 2026.
- Canadian Radon Services Index, for the survey figures (radon levels), the contractor count and the geometric mean. Records checked 18 to 27 October 2026. Its radon map explorer (opens in a new tab) was checked 30 October 2026.
- Health Canada's radon guideline, for the 200 Bq/m³ guideline, and About radon, for how homes next door can differ. Checked 30 October 2026 and 2 November 2026.
- Statistics Canada, 2021 Census, for the towns in the Windsor census metropolitan area.
- WECHU, Information about radon testing and the Kingsville Times, October 2025, for the library loan.
You're welcome to link to this page or cite it. If you use the survey's figures, quote them as printed and credit the survey.
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