About Canada Radon

Canada Radon publishes community-level indoor radon context from Health Canada's Cross-Canada Survey of Radon Concentrations in Homes and related open releases. City pages show survey-based average concentration, the share of tested homes at or above the 200 Bq/m³ guideline where published, and a risk category derived from those aggregates.

Guideline and testing

Health Canada's indoor radon guideline is 200 Bq/m³ in the normal occupancy area (lowest lived-in level). Remedial measures are recommended within a reasonable time frame at 200–600 Bq/m³, and within about one year above 600 Bq/m³. Long-term testing (minimum three months, ideally including heating season) on the lowest lived-in level is the reference method. Measurement and mitigation professionals are certified through the Canadian National Radon Proficiency Program (C-NRPP).

Methodology notes

Survey geographies are summaries of participating long-term tests, not a measurement of every dwelling and not an annual retest calendar. When a municipality lacks its own breakout, pages use the nearest regional or provincial survey geography and label the tier. Multi-year rankings may carry a survey vintage forward only when labeled static; pages do not invent yearly municipal retests. A city average never replaces a test of a specific home. Primer: Indoor Radon in Canada: Guideline, Testing, and Geology.

Limitations

Figures are for informational and comparative use. For decisions with health, tax, or construction consequences, rely on the issuing municipality or agency, a licensed professional, or Health Canada guidance where applicable. Corrections: [email protected].

Topic-specific ingest rules live on this atlas methodology and data sources pages. Plain-language primers for all topics are collected under guides.