Every radon measurement Health Canada has published, mapped, with the 2024 national survey set against it. Free, independent, and nothing on it is for sale.
Health Canada long-term tested homes in 33 metropolitan areas. Each circle is one of them, sized by how many homes were tested and coloured by the share that came back at or above Canada's action level.
Tap any city for its numbers. Between 68 and 107 homes were tested in each, which is enough to describe a city and nowhere near enough to describe a street.
By the share of tested homes at or above 200 Bq/m³.
| Metropolitan area | Homes tested | Median Bq/m³ | At or above 200 | |
|---|---|---|---|---|
| Regina · SK | 96 | 216 | 56% | |
| Winnipeg · MB | 99 | 194 | 47% | |
| Halifax · NS | 96 | 100 | 31% | |
| Thunder Bay · ON | 92 | 110 | 30% | |
| Kingston · ON | 95 | 128 | 26% | |
| Sherbrooke · QC | 104 | 90 | 24% | |
| Windsor · ON | 92 | 120 | 24% | |
| Saskatoon · SK | 104 | 140 | 21% | |
| Guelph · ON | 101 | 73 | 20% | |
| Québec · QC | 94 | 65 | 17% | |
| Saint John · NB | 107 | 74 | 17% | |
| Greater Sudbury · ON | 94 | 99 | 16% | |
| Calgary · AB | 99 | 112 | 15% | |
| Kelowna · BC | 106 | 88 | 15% | |
| Montréal · QC | 92 | 76 | 14% | |
| Brantford · ON | 85 | 72 | 14% | |
| Saguenay · QC | 90 | 59 | 13% | |
| Ottawa - Gatineau · QC | 105 | 84 | 10% | |
| Edmonton · AB | 96 | 108 | 8% | |
| London · ON | 80 | 65 | 8% | |
| St. John's · NL | 89 | 78 | 7% | |
| Moncton · NB | 90 | 62 | 7% | |
| Peterborough · ON | 100 | 84 | 6% | |
| Hamilton · ON | 87 | 62 | 6% | |
| Barrie · ON | 83 | 69 | 5% | |
| Vancouver · BC | 68 | 27 | 1% | |
| Abbotsford · BC | 84 | 48 | 1% | |
| Oshawa · ON | 92 | 46 | 1% | |
| Kitchener · ON | 101 | 57 | 1% | |
| Victoria · BC | 89 | 32 | 0% | |
| St. Catharines - Niagara · ON | 84 | 46 | 0% | |
| Toronto · ON | 86 | 48 | 0% | |
| Trois-Rivières · QC | 89 | 41 | 0% |
Source: Health Canada, Radon and Thoron Data From Canadian Homes. Medians are used rather than averages because one very high reading distorts an average in a small sample.
The Prairies are the problem. Regina and Winnipeg sit far above everywhere else, with 56% and 47% of tested homes at or above the guideline and medians of 216 and 194 Bq/m³. Saskatoon follows at 21%. The 2024 national survey reaches the same conclusion from a much larger sample.
Atlantic Canada is higher than people expect. Halifax has 31% of tested homes over the line, Saint John 17%, St John's 7%. The 2024 survey adds Bathurst to the list of towns where a quarter to a half of homes are over.
Ontario splits sharply. Thunder Bay is at 30% and Kingston at 26%, while Toronto, Oshawa, Kitchener and St Catharines are at or near zero. Being in Ontario tells you almost nothing; being in Thunder Bay tells you a lot.
Alberta is middling, and its small towns are not. Calgary is at 15% and Edmonton at 8%. But the 2024 survey names High River, Okotoks and Strathmore among the towns where a quarter to a half of homes are over the guideline. The countryside around the cities is considerably worse than the cities.
British Columbia is two provinces. Vancouver, Victoria and Abbotsford are among the lowest readings in the country. The interior is not: Kelowna, Prince George, Nelson, Vernon, Penticton and Trail all appear in the 2024 survey's list of the worst affected.
Quebec is mostly low with exceptions. Trois-Rivières and Saguenay are low, Montreal is at 14%, and Sherbrooke is at 24%.
Two patterns hold across all of it. Rural beats urban for high radon, and single-detached houses beat semi-detached, which beat row housing. Both come from the 2024 survey.
The 2024 Cross-Canada Survey of Radon found that about 17.8% of people in Canada live in buildings at or above the 200 Bq/m3 guideline, up from 6.9% in the previous survey. A further 24.2% live between 100 and 199. There is no radon-free part of Canada.
There is no safe level. Health Canada acts at 200 Bq/m3, the US EPA at about 148, and the World Health Organization sets a reference level of 100. These are action levels, not safety guarantees.
On the measurements mapped here, Regina and Winnipeg are the worst of the 33 metropolitan areas, with 56% and 47% of tested homes at or above the guideline. Vancouver, Victoria and Toronto are the lowest. The 2024 survey also names High River, Okotoks, Strathmore, Kelowna, Prince George and Whitehorse among towns where a quarter to a half of homes are over the line.
No. Radon varies enormously between neighbouring houses, because it depends on how each building sits on and draws air from the ground beneath it. A map shows where measurements were taken and what they read. Only a test in your home describes your home.
More questions, answered properly.
Sources. Health Canada, Radon and Thoron Data From Canadian Homes and Cross-Canada Survey of Radon Concentrations in Homes, both on the federal open data portal under the Open Government Licence. Cross-Canada Survey of Radon working group (Evict Radon National Study, BC Centre for Disease Control, Health Canada), Cross-Canada Survey of Radon Exposure in the Residential Buildings of Urban and Rural Communities, 2024, Version 1, at crosscanadaradon.ca. Certification data from the Canadian National Radon Proficiency Program.