[en] A study was conducted to evaluate the precision and accuracy of Track-Etch passive radon detectors manufactured by the Terradex Corporation. Four configurations of these detectors were exposed to known radon concentrations in the Eastern Environmental Radiation Facility radon chamber under varying exposure regimines and sent to Terradex for processing and readout. Data reported by Terradex and our own exposure concentrations were used to calculate calibration numbers for each configuration which were then compared to calibration numbers used by Terradex. Results of our study indicate that groups of detectors exposed together and processed together demonstrate similarity in response. Groups of detectors exposed and processed at different times, however, did not always agree with each other nor with published Terradex calibration numbers