MS-QA_06-2019 rev5

ANSI/AARST MS-QA 2019 14 Radon Measurement Systems Quality Assurance Continuous Radon Monitors (CRM) 4.3.3 CRM Calibration—Exposure Conditions The calibration concentration is to be between 10 and 80 pCi/L. Note—Additional calibration concentrations outside this range may be included in calibration operations. The CRM being calibrated is to have a proportional response to radon concentrations in the range of environmental conditions and radon concentrations to which it is exposed during routine use; this proportional response is assumed by the calibration facility. CRMs that meet the proportionality requirements of ANSI/AARST MS-PC meet this requirement. As described in Section 3.4 , if a CRMmanufacturer has documented the lack of effect of temperature or relative humidity on radon concentration in reports available to credentialing authorities (subject to confidentiality agreements), then calibration requirements do not need to include exposures to different temperatures and relative humidities; however, the average temperature, relative humidity and barometric pressure must be recorded during the calibration exposure. 4.3.4 CRM Calibration—Components and Authority CRM calibration shall include the following components, all of which are to be documented: — Verification of the “as received” status. — Device readiness evaluation and operating parameters check, such as replacing batteries and verifying voltages and currents for some methods. — Background assessments, using aged air or nitrogen, for at least 24 hours (including an initial 4 hours to bring the CRM to equilibrium) or as agreed upon between the calibration facility and the CRM provider, such as for 16 hours. Informative advisory —The optimal ratio for background-to- calibration time is a common calculation in radioanalysis (e.g., Wang and Willis 1965) and should be used as guidance for whether longer background counting times are needed. — Adjustment of device response, if necessary, including a second exposure if needed to verify that the adjustment was successful according to the device manufacturer’s instructions. The calibrating facility is responsible to have obtained written authority from the manufacturer or the provider to conduct the calibration , because calibrations may often include adjusting the device response, replacing parts or other procedures indicated by the manufacturer. 4.3.5 CRM Calibration—Documentation For instruments that produce radon concentration values that are retrieved and reported by the field measurement provider, calibration stickers that are visible on the outside of the CRMmust include the facility and date of calibration , due date for recalibration and serial number. If there are factors that are required for the user to calculate concentration, these must be included on the sticker. Note—These may include instrument background value as assessed (or assumed, if necessary) in units applicable to the method (count rate or concentration), and calibration factor (response/concentration). Exception: If instruments offer field results accessible only by the manufacturer or approved third parties, a calibration sticker shall provide field measurement providers with all relevant information that is required by state or other relevant credentialing authorities. Calibration facilities shall provide a calibration certificate or statement with the calibrated CRM that contains the same information that is on the calibration sticker plus the conditions to which the monitor was exposed, average radon concentration, environmental conditions (temperature, relative humidity, barometric pressure) and duration of exposure.