# Ontario Radon Gas Testing and Mitigation: Health Risk, Testing Methods & Costs 2026

**URL:** <https://home.renovation.reviews/t/ontario-radon-gas-testing-and-mitigation-health-risk-testing-methods-costs-2026/46889>\
**Category:** Ontario\
**Created:** [April 26, 2026, 6:49pm UTC](https://home.renovation.reviews/t/ontario-radon-gas-testing-and-mitigation-health-risk-testing-methods-costs-2026/46889 "2026-04-26T18:49:02Z")\
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**Post date:** [April 26, 2026, 6:49pm UTC](https://home.renovation.reviews/t/ontario-radon-gas-testing-and-mitigation-health-risk-testing-methods-costs-2026/46889/1 "2026-04-26T18:49:02Z")

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Radon is the second leading cause of lung cancer in Canada after smoking. Ontario has significant radon risk zones. Here is what homeowners need to know in 2026.

**What Is Radon?**  
Radon is a naturally occurring radioactive gas that forms from uranium decay in soil and rock. It enters homes through foundation cracks, sump pits, floor drains, and construction joints. Odourless and colourless — only testable, not detectable by senses.

**Ontario Risk Areas**  
Notable elevated radon areas: parts of Ottawa, Bancroft, Sudbury, and scattered locations across GTA and cottage country. Health Canada action level: 200 Bq/m3. Approximately 7% of Canadian homes exceed this level.

**How to Test**  
Long-term alpha track test (90-day minimum): most accurate. Place detector in lowest liveable area. Send to certified lab. Cost: $30-$60 DIY kit. Recommended for all Ontario homes — especially those with finished basements.

**Mitigation: Active Soil Depressurization (ASD)**  
ASD is the standard Ontario mitigation method. A pipe and fan draws radon from under the foundation slab and exhausts it outside. Installed by C-NRPP certified contractor. Cost: $1,500-$3,000. Reduces radon by 80-99%.

**When to Test**  
Test any home before purchasing. Test after significant air sealing work. Test periodically (every 2-5 years) as radon levels can change.

Discuss radon testing results and find Ontario mitigation contractors at home.renovation.reviews.