Summary
Receiving high radon test results in a workplace can feel overwhelming—but the path forward is clear and manageable. This guide walks Ontario business owners through exactly what happens after a high radon reading, from confirmation testing to mitigation and follow-up.
Step 1 – Confirm the Test Results
If a radon test shows levels above 200 Bq/m³, Health Canada considers action necessary.
Short-Term vs. Long-Term Results
- Short-term tests (less than 90 days) can flag potential issues quickly
- Long-term tests (90+ days) confirm average exposure and guide next steps
If a short-term test is high, a long-term test is often recommended before mitigation—unless levels are significantly elevated.
Step 2 – Assess Exposure Risk in the Workplace
Not all elevated radon readings carry the same risk. A professional assessment considers:
- How long employees spend in affected areas
- Whether workspaces are at or below ground level
- Airflow patterns and ventilation systems
- Building construction and foundation design
This ensures mitigation is targeted and effective, rather than over- or under-correcting.
Step 3 – Contact a Certified Radon Professional
Commercial radon mitigation should always be handled by a C-NRPP-certified radon professional.
What a Professional Will Do
- Review test data and building layout
- Identify radon entry points
- Design a mitigation system suited to commercial use
- Coordinate installation to minimize business disruption
Professional systems are engineered to meet Health Canada guidelines and workplace safety expectations.
Step 4 – Install a Radon Mitigation System
Common Commercial Mitigation Solutions
- Sub-slab depressurization systems
- Sealing foundation cracks and penetrations
- HVAC pressure balancing where appropriate
Most commercial installations are completed with little to no downtime, depending on building size and complexity.
Step 5 – Post-Mitigation Testing
After mitigation, follow-up testing is essential.
Why Retesting Matters
- Confirms radon levels have been reduced below 200 Bq/m³
- Provides documentation for health and safety records
- Demonstrates due diligence under Ontario workplace safety expectations
Many businesses choose to retest periodically as part of their ongoing indoor air quality strategy.
Step 6 – Communicate With Employees
Transparency builds trust.
Business owners should:
- Share that testing was conducted
- Explain what the results meant
- Outline steps taken to address radon
- Provide reassurance backed by post-mitigation results
Clear communication reduces concern and reinforces a commitment to employee well-being.
High Radon Levels Are Fixable
A high radon test is not a failure—it’s an opportunity to correct a hidden issue before it becomes a serious health risk. With proper testing, professional mitigation, and follow-up, businesses can create safer indoor environments and reduce long-term liability.
Not sure when to test for Radon? Check out our post on Radon Testing for Commercial Properties.