Dosimetry ²²²Rn in the air of the municipal spa of Águas de Lindóia and of spa Thermas Antônio Carlos

Human beings are constantly exposed to different sources of radiation. Among them, the natural sources, which reach the world's population at a relatively constant rate for a long period of time, are highlighted. It is estimated that the average annual dose received by the population due to natural sources is 2.4 mSv y^-1. Some bathhouses and spas found around the world are of great importance when considering the aspects of radiological protection, because they concentrate significant concentrations of radionuclides, for instance, the ²²²Rn gas. Based on this, the dosimetry of ²²²Rn in the air was performed for workers and individuals of the public in two brazilian bathhouses; Águas de Lindóia municipal bathhouse in the state of São Paulo and Thermas Antônio Carlos bathhouse in the city of Poços de Caldas, state of Minas Gerais. The passive detection method was used, with the use of solid detectors of type CR-39® (Columbia Resin) inserted in diffusion chambers of the type NRBP® (National Radiological Protection Board). The concentrations of ²²²Rn in the air ranged from 27 ± 4 Bq m^-3 to 16451 ± 298 Bq m^-3 for the Águas de Lindóia Municipal bathhouse and 35 ± 3 Bq m^-3 to 156 ± 4 Bq m^-3 for the Thermas Antônio Carlos bathhouse. Three exposure scenarios were considered for the dose assessment in both bathhouses. The first scenario corresponds to the exposure of workers who apply thermal baths to users, the second scenario corresponds to the exposure of workers who perform maintenance in the hot springs and the third scenario covers the assiduous regulars of the thermal baths. The effective dose values found in the Águas de Lindóia Municipal bathhouse and in the Thermas Antônio Carlos bathhouse, respectively, considering the first scenario range from 0.10 to 0.34 mSv y^-1 and 0.17 to 0.33 mSv y^-1. The value found, considering the second scenario range from 0.24 to 9.9 mSv y-1 to the Águas de Lindóia bathhouse and from 0.03 to 0.09 mSv y^-1 to the Thermas Antônio Carlos bathhouse. Considering the third scenario, the dose values found range from 0.01 to 0.02 mSv y^-1 for both bathhouses. (author)