Indoor radon concentrations in Greek apartment dwellings.

Radon concentrations indoors were determined in 24 typical occupied apartments in the city of Thessaloniki, North Greece (40 degrees 38'N, 22 degrees 58'E), by means of 12 surveys, each 2 mo long, over a 2-y period starting October 1989. The ratio of the winter and summer averages for the first year of measurements was 1.8 +/- 0.78, and for the second year of measurements was 1.6 +/- 0.61. The indoor radon concentration in the summer (1990) period ranged between 8 and 81 Bq m-3, while in the winter (1989-1990) it ranged between 20 and 143 Bq m-3 for the first year of measurements or between 8 and 92 Bq m-3 in the summer (1991) period and between 12 and 119 Bq m-3 in the winter (1990-1991) for the second year of measurements. These results were obtained by type CN-85 alpha track detectors. Some parameters that influenced the concentrations, such as precipitation rates and use of fly ash in building materials, are discussed.