
Ontario’s Radon Risk: Is Your Home Affected?
According to Canada Radon’s Ontario Radon Map, some regions have significantly higher-than-average radon levels, with many homes testing above the Health Canada safety guideline of 200 Bq/m³. The only way to know if your home in Ontario is affected is to conduct a professional radon test.
High-Risk Radon Areas in Ontario
Homeowners in the following areas should be especially vigilant about radon testing:
- Greater Sudbury & Northern Ontario – Many homes test well above 200 Bq/m³.
- Ottawa & Eastern Ontario – Documented high levels in basements and crawl spaces.
- Hamilton, Niagara, and Southwestern Ontario – Mixed radon levels, with certain pockets exceeding safe limits.
- Toronto & the GTA – While lower on average, individual homes still test above safe limits.
Since radon exposure is cumulative, even moderate levels over long periods can significantly increase lung cancer risk. A professional radon test in Ontario can determine if mitigation is necessary.

