MS-QA_06-2019 rev5

ANSI/AARST MS-QA 2019 2 Radon Measurement Systems Quality Assurance Definitions 2 DEFINITIONS Alpha Track Detector (ATD): Radon detector constructed from a piece of plastic, typically of either allyl diglycol carbonate or cellulose nitrate, inside a chamber usually made of electrically conducting plastic. Radon diffuses passively into the chamber, where it subsequently decays. Alpha particles emitted from radon and two of its short-lived progeny, 218 Po and 214 Po, strike the plastic detector and create damaged volumes or “latent tracks.” The plastic is etched in a caustic solution, which produces tracks that are visible with a microscope because the latent tracks are more soluble than the surrounding undamaged material in such a solution. As constant as practicable: This term is defined by agreement between the provider of the device(s) and the operator of the standard test atmosphere for radon ( STAR ) and considers the inherent function of the device(s) and the design limitations and operational requirements of the STAR . Audit : As defined by the U.S. EPA, an audit is a systematic and independent examination to determine whether quality activities and related results comply with planned arrangements and whether these arrangements are implemented effectively and are suitable to achieve objectives (U.S. EPA 2002). Batch: The set of material that is considered to be homogenous regarding characteristics that determine the calibration relationship. For example, activated carbon is prepared and sold in batches, which are then used by laboratories to construct devices with that carbon; a single plastic melt is sold to laboratories who manufacture many ATDs from that batch. Note—For quality control efforts in the field, conducting spikes relative to each batch of manufactured products or lots of products purchased on a specific date can be a useful verification of quality. Blanks: A type of quality control (QC) check that quantifies detector response due to factors other than the measurement itself. Blanks are devices deployed to measure effects on the measurement result from anything other than the environment tested, i.e., effects caused during storage, shipping, handling and transport. The purpose of blanks for in-control operations is to verify and document the lack of influence of factors encountered outside the measured environment; their records are necessary to support data validity. Blind : A type of performance test of the analytical capability of a method in which a sample is not identified as a performance test to the analyst. Note—When QC detectors are processed at an analysis laboratory, best practices dictate that they should be treated and labeled as other routinely returned detectors and should not to be identified as QC detectors. As sometimes required by state regulators or as part of coordinated QC efforts with the laboratory, it may be acceptable to identify QC detectors to the analyst. Calibration: To adjust or determine or both, the response or reading of an instrument or device relative to a series of conventionally true values (U.S. DOE 2011). Calibration Factor: That factor or function that represents the relationship between the method’s response and the concentration to which it is responding. The calibration relationship is the ratio of “rise,” or the response (dependent variable represented on the vertical axis), to the “run” of the concentration being analyzed (independent variable represented on the horizontal axis). In all cases the calibration factor is based on measurement system response divided by the concentration or integrated concentration to which it is responding. Charcoal Adsorption Device (CAD) Methods : This class of device employs a material such as activated charcoal that adsorbs radon from the air. The amount of radon adsorbed depends on the design of the device, the type of charcoal, the exposure time and the radon