Canada Radon Map

Methodology & sources

Data: 2024 Cross-Canada Survey of Radon (69,478 long-term tests, 2009–2024) + Health Canada 2009–11 survey + NRCan airborne uranium (GSC Open File 7402, doi:10.4095/293359) — including ~10-km ground readings for 429 postal areas (FSA). Page updated July 2026.

This map lets you compare two independent national surveys. The default is the 2024 Cross-Canada Survey of Radon — the largest residential radon dataset in Canada (69,478 long-term tests, 2009–2024), assembled by a working group of the Evict Radon National Study, the BC Centre for Disease Control, and Health Canada.

• The map. Every one of Canada’s 293 census divisions is shaded by its measured radon; the survey publishes 190 reporting areas (each n≥25) covering 278 divisions, and 15 divisions are shown grey as “not enough data.” Participants chose to test, so area rates can run higher than a random-sample survey would show. Boundaries are Statistics Canada’s 2021 cartographic files, simplified by us; the shading and design are our own rendering of the survey’s published figures. Cities and metros are marked as points with their own weighted numbers.
• What the colours mean. Each census division, city and metro is shaded by the share of tested homes at or above your chosen level — the WHO reference (100 Bq/m³), the US EPA action level (148 Bq/m³ = 4 pCi/L), or Health Canada’s guideline (200 Bq/m³). By default this map shows the WHO reference level (100 Bq/m³) — the most protective benchmark; switch to the US EPA (148) or Health Canada (200 Bq/m³) levels anytime.
• Typical level is the geometric mean — the middle of the range for that area. Radon is log-normally distributed, so a minority of homes sit far above the average; that is why testing your own home is the only way to know.
• The EPA figure (148 Bq/m³) falls between the survey’s published 100 and 200 bands, so we estimate it with a log-normal fit to each area’s own reported percentages — no survey figure is altered. Where an area reported 0% above 200, the 148 figure is estimated conservatively from its 100 figure.
• Health risk. At the EPA action level, the US EPA projects about 7 in 1,000 lifetime lung-cancer cases among people who never smoked and 62 in 1,000 among smokers; the WHO estimates risk rises ~16% per 100 Bq/m³.
• The ground layer. Each area result also shows the uranium measured in the ground by NRCan’s airborne gamma-ray surveys (Radioactivity Map of Canada, GSC Open File 7402, Open Government Licence, doi:10.4095/293359), shown as an area mean — the source material radon comes from, and a measurement, not a model. Our calibration against the 2024 survey: it tracks how often areas exceed 100 Bq/m³ (r ≈ 0.6, n = 57 regions) but is weak at 200+ (r ≈ 0.3); housing, soils and winters decide the rest. Where the survey never flew — including most of BC, southern Ontario and the Montréal region — we say so instead of guessing. Ground data can flag an area; it can never clear one. Research & analysis: RadonTest.ca, 2026 — to our knowledge, the first Canadian map (as of July 2026) to pair measured indoor radon with geological source potential in one view.