  Using high--sensitivity radon (Rn-222) portable detectors (passive electronic
devices of the type RADIM3), the airborne Rn-222 concentration in the interior
of various Cypriot buildings and dwellings was measured. For each preselected
building and dwelling, a calibrated detector was put into a closed room, and
the Rn-222 concentration was registered in sampling intervals of 2 to 4 hours
for a total counting time of typically 48 hours. Rn-222 activity concentrations
were found to be in the range of 6.2 to 102.8 Bq/m**3, with an overall
arithmetic mean value of (19.3 +- 14.7) Bq/m**3. This value is by a factor of
two below the world average (population-weighted) value of 39 Bq/m**3. The
total annual effective dose equivalent to the Cypriot population was calculated
to be between 0.16 and 2.6 mSv with an overall arithmetic mean value of (0.49
+- 0.37) mSv.
