Canada Radon
Atlas of Radon Levels

Radon Levels in Toronto

Ontario · Cross-Canada Radon Survey · 2025 data

By Canadian Radon Data Team · Sourced from official open data

Direct municipal data
157Bq/m³Guideline watch
0600+Guideline200 Bq/m³
Mean indoor radon
157 Bq/m³
Ontario avg: 163 Bq/m³
Homes above 200 Bq/m³
17%
Provincial avg: 22%
Risk category
Moderate
Reference: 200 Bq/m³

Community summary

Average radon in Toronto is 157 Bq/m³; 17% of homes exceed 200 Bq/m³.

Figure 1 · Geology

Limestone beneath Toronto

Toronto sits on Limestone bedrock or surficial deposits. Radon enters homes through cracks in foundations, sump pits, and utility penetrations. Geology explains regional averages, but individual home levels depend on construction, ventilation, and soil contact.

Toronto vs Ontario

Toronto mean radon157 Bq/m³
Ontario provincial average163 Bq/m³
Health Canada reference level200 Bq/m³
Homes above 200 Bq/m³17%

Testing strongly advised

17% of tested homes in this area exceed 200 Bq/m³. Individual homes vary — the only way to know your level is to test.

  • 1Order a Health Canada approved long-term test kit
  • 2Place the detector on the lowest occupied level for 3+ months
  • 3Send the kit to the lab and compare results to 200 Bq/m³
  • 4Retest every 2 years or after major renovations

Sponsored

Order a long-term radon test kit

Health Canada recommends a minimum 3-month test during heating season. Long-term kits give a more accurate picture than short 2-day charcoal tests.

Browse test kits on Amazon.ca →
Source · Health Canada Cross-Canada Radon Survey (seed). Last updated 2025. Refreshed on the site's automated schedule.