PREDICTING THE ANNUAL CONCENTRATION OF INDOOR RN-222 FROM ONE OR MORESHORT-TERM MEASUREMENTS

Long-term and short-term measurements of indoor Rn-222 from 480 houses located in eleven states were used to study the relationship between the annual living area average (ALAA) and 1) a single 2 d measurement and 2) the mean of multiple 2 d measurements (taken in different seaso ns). Of particular interest is the issue of using a short-term measure ment(s) to predict the ALAA in a given house. The results indicate tha t with 95% confidence (approximately): 1) a single 2 d measurement giv es an interval estimate of the true ALAA that is within a factor of 2. 5 of the predicted ALAA; and 2) a mean of two 2 d measurements (taken in different seasons) gives an interval estimate that is within a fact or of 2.2 of the predicted ALAA. If a more precise estimate of the ALA A is needed, then an alternative procedure to using 2 d measurements s hould be employed (e.g., measure the annual concentration directly).