Commercial Radon Testing

Radon is a naturally occurring, colorless, and odorless radioactive gas that results from the decay of uranium in soil, rock, and water. When this gas enters a building through cracks in the foundation or other openings, it can become trapped, accumulating to dangerous levels.

The health concern stems from the fact that inhaling radon's radioactive decay products (progeny) can damage the DNA in lung tissue, which is scientifically proven to significantly increase the risk of lung cancer over time.

Most people spend approximately one-third of their lifetime at work (or at school/healthcare facilities). If a commercial building has high radon levels, employees, tenants, or visitors are exposed to those concentrations for many hours each day, leading to significant cumulative lifetime risk. Commercial property owners and managers have a duty of care to ensure a safe environment, making testing an essential liability and health measure.

The U.S. Environmental Protection Agency (EPA) recommends taking action to reduce radon levels in buildings if the concentration is 4.0 picocuries per liter pCi/L of air or higher.

While this level was originally set for residences and schools, it is the most widely adopted guideline and is often used by environmental professionals and many governmental agencies (like the GSA) as the threshold for recommending mitigation in commercial spaces.

Commercial buildings present unique testing challenges compared to homes:

• Size and Structure: Their large slabs and complex foundation features can create multiple entry points for radon.

• HVAC Systems: Powerful, complex ventilation systems, especially those that create strong negative pressure within the building (stack effect), can actually draw more radon gas from the soil into the lower floors.

For this reason, commercial testing requires specialized protocols (like those from ANSI/AARST) and the strategic placement of multiple monitors to get an accurate reading across large, occupied areas.

Radon typically enters a building from the ground, meaning the highest concentrations are almost always found in areas that are in direct contact with the soil. These include:

• Basements
• Ground-floor offices or classrooms
• Crawl spaces
• Rooms above tunnels or underground utility vaults

Any space that is frequently occupied on or below the grade level should be prioritized for testing.

If a commercial property tests at or above the EPA's recommended action level (pCi/L), the owner has both a health and potential legal obligation to act. The next step is to install a radon mitigation system, typically an Active Soil Depressurization (ASD) system.

This system uses a fan and piping to draw the radon gas from beneath the building's slab and safely vent it above the roofline before it can enter the occupied spaces.

The recommendation for retesting varies based on the initial results and any changes to the building:

• After Mitigation: Testing must be performed immediately (24 hours to 30 days) after a mitigation system is installed to confirm its effectiveness, and then every two years thereafter to ensure the system is still functioning correctly.

• Baseline Testing: If the initial levels were low, retesting is still recommended every five years or after any major renovations, HVAC upgrades, or foundation work that could alter the building's internal air pressure or radon entry dynamics.