An approach for long-term (either retrospective or prospective) Rn-222 meas
urements is proposed that is based on the combination of the high radon abs
orption ability of some polycarbonates with their alpha track-etch properti
es. The detection limit is projected to be < 10 Bq m(-3) for an exposure ti
me of 20 yr. (C) 2000 Elsevier Science B.V. All rights reserved.