MS-QA_06-2019 rev5

ANSI/AARST MS-QA 2019 19 Radon Measurement Systems Quality Assurance EIC Analysis 6 ANALYSIS OF EICs 6.1 QA Required The analysis service provider or laboratory shall be responsible for developing, documenting and implementing its own procedures for defensible QC processes and assessments within the context of its own operation’s quality management system. QC records are to be maintained and retained so that QC processes can be reviewed for internal QC improvement and available if needed to auditors or credentialing authorities, subject to confidentiality agreements. Results of QC checks are to be recorded, evaluated and used to improve quality performance when using the EIC method. QC checks that are required when using EIC methods include both: a) QC checks conducted during field operations in accordance with Section 5 ; and b) Additional QC requirements conducted in association with analysis that include: 1. Detector condition (including maintenance, storage and transport) 2. Verification of acceptable analysis environment 6.1.1 EIC Operations and Responsibilities Ensuring that QC checks are conducted, including field operation QC checks for detector condition, blanks , spikes and duplicates , is the responsibility of: a) the QP when engaged in both field operations and detector analyses, or b) the analyst when field operations are conducted by other individuals. These responsibilities include adequate training for individuals for each task required in the EIC chain of custody including both field operations and detector analysis. 6.2 Informative Description of the EIC Method The EIC detector consists of: a) an ion chamber made of an electrically conductive plastic, and b) an electret as the detecting mechanism. The electret is typically an electrically charged disk that is housed in an electrically conductive plastic holder. The surface voltage of the electret is positively charged and, when attached to the ion chamber, ionization that results from the decay of radon and its decay products within the chamber reduces the voltage of the electret. EIC analysis entails measuring the electret surface voltage both before and after field deployment by a special surface voltage measurement device. The loss of surface voltage, duration of the exposure, elevation, ambient gamma exposure rate and configuration-specific calibration factors are used to calculate the average radon concentration. 6.3 EIC Analysis QC—Condition of Detectors Standard operating procedures are to include checks for the integrity of the chambers and the electrets during storage, transport and immediately before and at the end of each measurement. 6.3.1 EIC Analysis—Visual Inspections of Detectors Visual inspections are to include checking the condition and cleanliness of the outside or inside of the chamber, chamber closure, loose cap or spring and debris on the electret surface or other conditions that may affect the measurement. Any concerns encountered are to be logged and relayed to the QP responsible for data validation of test results and measurement systemmaintenance.