Three Developments Related to ANSI/HPS Standard N13.56

Three topics related to ANSI/HPS Standard N13.56, Sampling and Monitoring Releases of Airborne Radioactivity in the Workplace, are discussed. First, due to the omission of consideration of the activity's half-life in the standard's continuous particulate air monitor (CPAM) quantitative method, it is possible for concentration estimates produced by that calculation to be underestimated. Second, the concentration estimate found in air grab sampling, as discussed in the standard, is not, as claimed, an average unless the activity is "long-lived" (negligible decay during sampling). It is nonetheless possible for this calculation to produce a concentration estimate that is not significantly different from the average, depending on both the half-life of the activity and the sampling time. Third, the issue of when to change the filter for the CPAM method is addressed.