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Radon Testing: Closed House Conditions

closed down house due to radon testing

Protocol for short-term radon testing calls for "closed house conditions" to most accurately measure a home's potential for Radon exposure. Under closed house conditions the Radon trapped inside the structure is not diluted by outside air. In a short-term Radon test the closed house condition supports measurement of the maximum Radon level. However, closed house conditions are not required for long-term radon testing because long-term tests are intended to measure Radon levels occupants are exposed to under normal living conditions.

There are many factors that affect Radon levels in a house. Opening windows and exterior doors may cause radon levels to drop as indoor air gets diluted by outside air. But it is not unusual for Radon levels in a house to actually increase due to open windows. For example, an open window on the top floor of a house can cause more radon to be drawn into the basement as a result of the "stack effect." So, the best way to test radon, short-term, is under closed-house conditions.

Before you test, prepare for closed-house conditions:

  1. Testing apparatus should be placed at the lowest livable level
  2. Three feet from doors and windows, away from heat source or humidity
  3. Windows remain closed before and during the test
  4. Maintain regular entry and exit through exterior doors
  5. Maintain normal HVAC operation but no house or window fans
  6. If a mitigation system is in place, keep it running

If you have any questions about short-term testing in your home contact us or call us at (503) 719-6715.

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