Chapter 5 - Quality Assurance & Quality Control
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Measurement Duration

Initial measurements should be short-term in nature and performed under closed-building conditions.  Although multiple short-term and long-term tests give a better estimate of year-round average radon level an initial short-term test, which lasts for 2 to 90 days, ensures that residents are informed quickly should a home contain very high radon levels. Most often, short-term tests are necessary to meet the rigid timeline of a real estate transaction.

Initial Measurement – Initial measurements should be short-term, conducted to quickly identify buildings with elevated radon concentrations and to determine the next best action.

The following protocols must be followed for short-term measurements:

  • 2 – 90 days
  • Closed-building conditions must be initiated at least 12 hours prior to any test lasting less than 96 hours.
  • Closed-building conditions must be met for test duration of less than 7 days and closely adhered to for 7-90 day tests.
  • Unoccupied homes must be tested with the HVAC system set and operating throughout the measurement interval in the normal range such as 65-80 degrees.

Follow-Up Measurement – Short-term or Long-term measurements conducted in order to confirm an initial measurement and characterize elevated radon concentrations over a longer period of time. Best practice is to conduct follow-up measurements during opposite seasons to detect differences induced by mechanicals [HVAC] or changing weather.

The following protocols must be followed for long-term measurements:

  • 91+ days
  • Over multiple seasons or at least during heating season
  • Typically used in tests conducted for concerned homeowners not involvedin a real estate transaction.