  A systematic study of the indoor airborne radon concentration in the central
part of the Nicosia district was conducted, using high-sensitivity active radon
portable detectors of the type "RADIM3A". From a total of 108 measurements in
54 grids of 1 km^2 area each, the overall mean value is 20.6 \pm 13.2 Bq m^-3
(A.M.\pm S.D.). That is almost twice less than the corresponding average
worldwide value. The radon concentration levels in drinking water were also
measured in 24 sites of the residential district, using the high-sensitivity
radon detector of the type "RADIM3W". The mean value obtained from these
measurements is 243.8 \pm 224.8 mBq L^-1, which is relatively low compared to
the corresponding internationally accepted level. The associated annual
effective dose rates to each measurement were also calculated and compared to
the corresponding worldwide values. From the geographical coordinates of the
measuring sites and the corresponding radon concentration values, the digital
radon map of the central part of the Nicosia district was constructed for the
first time, by means of the ArcMap software package.
