Field study of indoor average radon-daughter estimation methods

The Technical Measurements Center conducted an Indoor Field Study during January 1984 through April 1985, using 44 sampling stations located in 28 structures in the Grand Junction, Colorado, area. The purpose of the study was to evaluate year-long measurement methods used to estimate the annual average indoor radon-daughter concentration (RDC) in a structure under actual occupancy conditions. The basis for evaluation was whether a method using an instrument could provide reasonable assurance of compliance with RDC standards, and whether the precision represented by the coefficient of variation of the instrument was 15% or less. The instruments evaluated were: Kodak-Pathe alpha-track film, Terradex SF detectors, Terradex type SO detectors, Technical Associates passive environmental radon monitor (PERM), EDA Instruments PERM, EML radon progeny integrating sampling unit (RPISU), EDA Instruments RPISU, and Eberline WLM-1. Conclusions and recommendations are given for each instrument.