34 unremediated dwellings in a high-radon area were monitored with three types of dose-integrating
radon detector. 20 homes were monitored for 4 consecutive 3-month periods and simultaneously for 12
consecutive 1-month periods; the remainder were monitored for 9 months (4 properties), 6 months
(6 properties) or 3 months (4 properties). In addition, 1-week measurements were made at 1-month
intervals, using co-located Track-Etch, Activated Charcoal and Electret detectors simultaneously.
Calibration of dose-integrating devices against continuous-monitoring systems confirmed good
responsivity and linearity. Although Track-Etch, Activated Charcoal and Electret devices are suitable
in principle for one-week measurements, zero-exposure offset and natural radon variability mean that
many one-week results will be equivocal and will need to be repeated. During the work, the chosen
Track-Etch detector supplier abandoned the market, necessitating identification of a replacement,
raising concerns over equivalence of results from nominally identical products from different sources
and necessitating statistical compensation. Analysis of the data-set permitted derivation of confidence
limits for the estimation of long-term average radon concentrations from short-term measurements.