7 Things That Cause Radon Levels To Fluctuate

Radon can enter a building through cracks, gaps, and other openings near the foundation. Since you cannot see or smell it, testing is the only way to know what your indoor levels look like. However, a single test result may only reflect what was happening during that specific testing window. Storms, pressure changes, HVAC use, and closed-up rooms are among the factors that cause radon levels to fluctuate. Here are seven things that can affect the indoor gas concentration.

Weather Patterns

Weather plays a major role in how radon moves through soil and into a commercial facility. Radon forms underground, then moves as air pressure, moisture, and small openings create paths towards the structure. As outdoor conditions shift, the pressure around your foundation may shift too. That movement can pull more radon indoors during certain periods.

Cold snaps can cause radon readings to rise because businesses often stay closed up, while warm indoor air pulls soil gas toward the foundation. Warm spells may change that pattern as outdoor temperatures shift pressure around the building and affect how much fresh air enters. Wind can also change readings by creating pressure differences around the structure, which may draw more radon through cracks and gaps.

For the most accurate picture, test during normal conditions with windows and doors closed as directed by the test instructions. If you test during unusual weather, follow up with another test later or choose a long-term test to better capture how radon levels change over time.

BarometricPressure

Barometric pressure describes the weight of the air outside your building. When that pressure drops, soil gas—the air in the spaces between soil particles—moves more easily toward the surface. Since radon travels with soil gas, changing pressure can affect indoor readings.

Storm systems, wind shifts, and other pressure changes may create short-term radon spikes. A reading taken during one weather pattern may look different from a reading taken a few days later. Therefore, follow-up testing can determine whether the level remains unchanged or shifts under certain conditions.

Rain and Soil Moisture

Rain can change radon movement by filling the open spaces between soil particles. As the ground becomes saturated, soil gas may move toward drier, more direct pathways rather than spreading through the soil as usual. When that happens, cracks, gaps, and unfinished areas of the foundation may provide radon an easier route into the property.

These conditions may affect radon readings after rain, snowmelt, or long damp periods:

• Saturated soil may push gas toward foundation openings.
• Frozen ground may trap gas below the surface.
• Poor drainage may increase moisture near the foundation.
• Open sump pits may create easier entry points.
• Damp crawl spaces may hold more soil gas near occupied areas.

Changes in the Foundation

Radon can enter through small openings in and around the foundation, including slab cracks, gaps around pipes, sump openings, crawl space soil, and joints where walls meet floors. Foundation conditions may change as a building settles, ages, or goes through repairs.

Settling Over Time

Structures settle as the soil beneath them compresses or shifts. As that movement happens, the foundation may develop small cracks, widen existing gaps, or pull slightly away from nearby materials. Those changes may create new openings where soil gas can move toward the facility.

Repairs and Renovations

Foundation repairs, plumbing work, basement updates, or other renovations can change how air moves beneath the structure. Additionally, new openings may appear near patched areas.

Drainage and Soil Movement

Poor drainage, erosion, or shifting soil may open small gaps or place extra stress on foundation materials. When the ground around the building changes, radon may find new routes indoors.

HVAC Use

Heating, cooling, and fan settings all influence air pressure inside a commercial building. A forced-air system may move air between floors, rooms, and unfinished spaces. If the system creates pressure differences, it may pull air from lower parts of the structure.

Since radon usually enters near the foundation, those pressure changes can affect readings. Leaky return ducts, exhaust fans, and ventilation systems may also pull replacement air through small openings near the foundation. After major HVAC or insulation work, retesting gives a clearer view of current conditions.

Crawl Space Conditions

Crawl spaces can influence radon because they sit close to the soil. Bare soil, torn vapor barriers, damp insulation, and poor sealing may allow soil gas and moisture to collect below the structure. Once that air enters the occupied areas, radon readings may rise.

These crawl space conditions may contribute to changing radon levels:

• Exposed soil may release radon directly below the building.
• Damaged vapor barriers may allow soil gas through.
• Standing moisture may affect soil gas movement.
• Gaps around penetrations may create entry points.
• Poor sealing may let crawl space air reach occupied areas.

Crawl space improvements may support a broader radon reduction plan. After testing and inspecting your commercial building, a certified radon professional can explain which solutions are best for your foundation, crawl space, and radon levels.

Testing Conditions

Testing conditions can make radon numbers look different from one test to the next. Device placement, test length, weather during testing, and closed-building conditions all affect the result. For example, a test placed near drafts or exterior doors may give a less useful reading. Proper setup helps the result reflect the radon levels more accurately.

Affordable Radon Southwest provides professional workplace radon testing services to deliver clearer, more reliable results for businesses. That means the test is placed correctly, run for the right amount of time, and reviewed with your structure’s conditions in mind. With professional testing, you can better understand whether your radon levels call for mitigation or follow-up testing.

Closed-Building Testing

Before and during a radon test, keep exterior doors and windows closed except when someone is coming in or going out. By doing this, the test measures the usual indoor air instead of a temporary change caused by fresh outdoor air. Heating and cooling systems can usually stay on, but window fans or whole-building fans may throw off the reading.

Radon levels can rise and fall in response to shifts in weather, soil moisture, pressure changes, airflow, and foundation conditions. A single test provides helpful information, but follow-up testing may give you a clearer picture. If your results are several years old or if your workplace has changed since the last test, it may be time to retest and confirm your current levels.