MALB_2014 with 1-21 Revisions

Conducting Measurements of Radon and Radon ANSI/AARST MALB-2014 with 1/21 Revisions Decay Products in Schools and Large Buildings 34 9.0 DEFINITION OF TERMS Terms not defined herein shall have their ordinary meaning within the context of their use. Ordinary meaning shall be defined in "Webster's Eleventh New Collegiate Dictionary." 9.1 Action Level A threshold for when mitigation of exposure to harmful elements is recommended or required. 9.2 Active Soil A radon control system involving fan-powered soil depressurization, including Depressurization (ASD) but not limited to sub-slab and sub-membrane depressurization. 9.3 Alpha Track Detector A radon detector constructed from a piece of plastic, typically of either allyl (ATD): 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. 9.4 Basic Heating and A dedicated heating and cooling system that does not supply additional outside Cooling air for ventilation. See Exhibit 6, Group 1. 9.5 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. 9.6 Becquerel per Cubic A unit of radioactivity representing one disintegration per second per cubic meter: Meter (Bq/m ³ ) 1 Bq/m 3 (0.027 pCi/L ). 9.7 Blank Measurements Blanks are detectors deployed to verify and document the absence of effects on the measurement resulting from sources other than the air being tested. Since blanks are not exposed (i.e., not left open to permit radon to enter the detector), their measurement value should be below theminimumdetectable concentration of the measurement system. See field blanks, office blanks and lab-transit blanks . 9.8 Calibration To adjust or determine or both, the response of an instrument or device relative to a series of conventionally true values. 9.9 Charcoal Adsorption This class of device employs a material such as activated charcoal that adsorbs Device (CAD) Methods : 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 concentration, temperature and relative humidity in the surrounding air. This class of device can provide an accurate representation of the average radon concentration during the exposure period if there are no large changes in radon concentration or the environment (e.g., temperature, humidity) during the exposure. Because of the half-life of radon and the time it takes for radon to adsorb, they are typically limited to exposure durations from 2 to 7 days. Calibration of a charcoal adsorption system is accomplished through exposures of representative sets of devices in a STAR for various time periods and different temperatures and humidities.