Indoor radon levels in primary schools of Patras, Greece.

Radon activity concentrations have been measured in 53 from a total of 66 public primary schools throughout of Patras, Greece, during December 1999 to May 2000 using solid-state nuclear track detectors (LR-115 II). The indoor radon levels in the classrooms were generally low, ranging from 10 to 89 Bqm(-3). The mean (arithmetic mean) indoor concentration was 35 +/- 17 Bq m(-3) and an estimated annual effective dose of 0.1 +/- 0.1 mSv y(-1) was calculated for students and 0.2 +/- 0.1 mSv y(-1) for teachers, assuming an equilibrium factor of 0.4 and occupancy factor of 12 and 14%, respectively. The research was also focused on parameters affecting radon concentration levels such as floor number of the classrooms and the age of the buildings in relation to building materials.