[en] A method of measurement of radon concentration in air was developed, based on high-sensitivity LiF:Mg,Cu,P (MCP-N, TLD Poland) thermoluminescent detectors installed in charcoal canisters. The canisters were exposed typically for 72 h in a calibration chamber with a radon concentration ranging from 100 Bq.m-3 to 87 kBq.m^-3. It was found that in these conditions the signal registered by the TL detectors was proportional to the ²²²Rn concentration and the lowest limit of detection (LLD) was at a level of 100 Bq.m^-3. The proposed method can be used in large-scale, multi-site surveys aimed at screening for high levels of indoor radon concentration or for measuring ground radon exhalation rates. (author)