In the period 2005-2006 a survey on natural radioactivity in about 500 schools located in south-east Italy (the Salento peninsula, province of Lecce) was carried out. In particular average radon concentration and average absorbed dose rate in air due to gamma radiation have been assessed by using solid state nuclear track detectors (SSNTD) and electret ionization chambers (EIC), as well as thermoluminescence dosimeters (TLD), respectively. SSNTD dosimeters were placed in every school, while electrets and TLD have been employed in a pilot study performed in a selected sample of 56 schools in order to achieve preliminary information. Moreover the study foresaw a quality control on electret dosimeters' perfomances in terms of homogeneity and reliability. The results of this check have been taken into account in the data analysis. In this paper final results concerning the pilot study are reported. The indoor radon levels measured in the schools ranged from 65Bq/m(3) to 1808Bq/m(3), and only six schools (corresponding to 13% of the sample) showed radon annual average above 500Bq/m(3), Italian action level for workplaces. For the average absorbed dose rate in air due to gamma radiation, the recorded values ranged between 47 and 83nGy/h with an average value of 61nGy/h.
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