Summary
Radon testing in commercial buildings isn’t one-size-fits-all. Offices, warehouses, retail spaces, and industrial facilities each present different risks. This post explains when commercial properties should test for radon, where tests should be placed, and how often testing should be repeated to protect employees and businesses.
If you haven’t yet, check out our post on Workplace Radon Exposure: What Business Owners Should Know
Why Commercial Radon Testing Requires a Different Approach
Unlike residential homes, commercial buildings often have:
- Larger footprints
- Multiple zones with different airflow patterns
- Slab-on-grade construction or underground parking
- Varying occupancy levels throughout the day
Because of this, radon testing in commercial spaces must be strategic and deliberate to accurately reflect employee exposure.
When Should Commercial Properties Test for Radon?
Business owners in Ontario should consider radon testing:
During Building Acquisition or Leasing
Before purchasing or leasing a commercial property, radon testing helps identify potential health risks and future liabilities early.
After Major Renovations
Changes to flooring, foundations, or HVAC systems can alter pressure dynamics and increase radon infiltration, even if previous tests were acceptable.
During Fall or Winter
As with homes, colder months provide the most reliable test results because buildings are sealed and radon levels tend to peak.
When Employees Work Below Grade
Any workplace with basement offices, storage areas, or workshops should be prioritized for testing.
Where Should Radon Tests Be Placed in Commercial Buildings?
Health Canada recommends testing all regularly occupied spaces at or below ground level.
Priority Areas Include
- Ground-floor offices
- Basements used as workspaces
- Retail units below street level
- Warehouses with slab-on-grade floors
- Mechanical rooms with regular staff access
In larger buildings, multiple tests may be required to account for variations across zones.
How Often Should Commercial Properties Test for Radon?
Radon testing is not a one-time task.
Recommended Testing Frequency
- Every 5 years under normal conditions
- After significant structural or HVAC changes
- After mitigation, to confirm effectiveness
- If occupancy patterns change (e.g., new basement offices)
Regular testing demonstrates due diligence and supports long-term workplace safety.
What Happens If Radon Levels Are Elevated?
If test results exceed 200 Bq/m³, Health Canada recommends mitigation.
Commercial Radon Mitigation May Include
- Sub-slab depressurization systems
- Sealing foundation joints and penetrations
- Pressure balancing through HVAC adjustments
When installed by a C-NRPP-certified radon professional, these systems are highly effective and typically cause minimal disruption to daily operations.
Read more about what to do if your radon levels are elevated.
Radon Testing Is a Smart Business Decision
Beyond compliance and health protection, radon testing helps businesses:
- Reduce long-term liability
- Support employee well-being
- Meet occupational health expectations
- Strengthen ESG and safety policies
Proactive testing signals that a business takes workplace safety seriously.
Protecting Employees Starts with Awareness
Radon exposure in commercial buildings is preventable. By understanding when to test, where to test, and how often, business owners can create safer environments and avoid unnecessary risks.
