Rn-222 Measurement Performance Criteria Melinda Ronca-Battista ANSI N42.51 Co-chair Phil Jenkins, Co-Chair Phil Jenkins Jim Burkhart Tom Voss Shawn Price Martin Smith Rick Straub Dave Kapturowski Leo Moorman Jani Palmer Dave Wilson Trudy Smith Gary Hodgden and assistants

Performance Criteria and Testing Framework How well devices perform, and How well devices perform, and How to prove it How to prove it

Performance Criteria All terms defined so we speak the same language Definitions: – Standard Test Atmosphere for Radon (STAR) – Device categories Continuous radon monitors – Minimum Detectable Concentration

Only 14 pages! All terms defined, with just a few equations

Criteria: Accuracy and Precision MDC Proportionality Temp Humidity

222Rn Measurement Performance Criteria Are primarily for residential and office environments – Not for special situations (rad materials) Are criteria for total error, imprecision, and MDC in various 222Rn concentrations, temp and humidities – Not a proficiency program, but could be adopted for use

222Rn Measurement Performance Criteria Are criteria that can be satisfied by existing data for calibration and tests already conducted by providers – Not extensive additional testing – Existing data can be used with appropriate documentation Does define method categories – Does not restrict mechanisms, designs

222Rn Measurement Performance Criteria Are explicitly defined statements of sets of conditions under which performance is tested and reported – Not calibration or QA/QC Are criteria for methods used for decisions on need for mitigation – Are not applicable to diagnostic, e.g., < 1 hour duration measurements

Continuous Radon Monitors: – Provides numeric, reviewable values – MDC <= 4 pCi/L for one-hour measurements – CF >= 2 cph per pCi/L May include: Scintillation cells Ion chambers Solid state (CF always = response/concentration)

Integrating Methods: Collects and accumulates an ongoing signal Result represents the average concentration during exposure May include: electrets Alpha track detectors Electronic detectors To comply with standard, device cannot display results for time periods < time for which it has met criteria. Devices that print/store/display results hourly but do not meet CRM definition are electronic integrating devices.

Equilibrating Methods: Not true integrating mechanisms May use adsorption of Rn Equilibrium between Rn adsorbed and in envt May be some dependency on temp and humidity Designs may slow desorption Analysis may include gamma spectroscopy, liquid scintillation

EACH device must be + 25% of avg Rn concentration (Individual Percent Error, or IPE) 6 – 15 pCi/L65 – 75 F10 – 55 %RH

Precision Precision: 5 devices must have COV < + 15% (COV=stdev/mean) 6 – 15 pCi/L65 – 75 F10 – 55 %RH

30-60 pCi/L Or 3 x the lower range 6-15 pCi/L AVG IPE low AVG IPE high Criterion: (AVG IPE low) – (AVG IPE high) < + 15% Proportionality Proportionality:

Calculation based on variability of background Tests not done in chamber Blanks, aged air or nitrogen 95% confident there is a “signal” that is detectable over the “noise” of bkg Criterion for Minimum Detectable Concentration: Min Meas. Duration Recommended by Provider MDC criterion > 1 hour4 pCi/L or less > 2 days1 pCi/L or less

Precision Criterion: 5 devices must have COV < + 15% Keep Rn Conc > 10 pCi/L and 10 – 25% RH Low temp: F High temp: F Temperature Temperature: Total Error Criterion: EACH device must be + 25% of avg Rn concentration (IPE)

Precision Criterion: 5 devices must have COV < + 15% Keep Rn Conc > 10 pCi/L and 65 – 75 F Low RH: 15 – 25 % RH High RH: 70– 80 % RH Relative Humidity Relative Humidity: Total Error Criterion: EACH device must be + 25% of avg Rn concentration (IPE)

Status of Standard: 1st round of many valuable comments already incorporated Now available for 2 nd round of comments Will be evaluated for revisions every 5 years Intent is to encourage more measurements and improve public health!