What is required before radon sampling regarding doors/windows?

What is required before radon sampling regarding doors/windows?

• A. Open all doors and windows for 12 hours prior
• B. Close all doors and windows for 12 hours prior
• C. No special procedure
• D. Seal all vents

Answer: (B)

Radon readings rely on how much outdoor air is mixing with indoor air. To get a representative indoor radon concentration, the space needs to be in a closed condition before and during the test. Closing all doors and windows for about 12 hours prior eliminates large, short-term changes in ventilation that would dilute radon from the indoors and skew the result. If you were to keep openings open, outdoor air would dilute radon and you’d likely get an artificially low reading. The other options either ignore the need to minimize ventilation or suggest actions that don’t align with obtaining a stable, representative measurement.

Radon readings rely on how much outdoor air is mixing with indoor air. To get a representative indoor radon concentration, the space needs to be in a closed condition before and during the test. Closing all doors and windows for about 12 hours prior eliminates large, short-term changes in ventilation that would dilute radon from the indoors and skew the result. If you were to keep openings open, outdoor air would dilute radon and you’d likely get an artificially low reading. The other options either ignore the need to minimize ventilation or suggest actions that don’t align with obtaining a stable, representative measurement.