Análise das concentrações de radônio em ambientes residenciais de Carambeí e Curitiba/PR

Abstract

Indoor radon gas concentrations represent a major source of human exposure to naturalradioactivity. Radon is part of the radioactive families of uranium (235U and 238U) and thorium (232Th). The soil where the residence is built and the materials used in the construction may contain elements such as uranium and thorium, and the radon gas, a product of the decay of these elements, manages to penetrate buildings through fissures and cracks, enabling them to be inhaled by living beings. The exposure of human beings to natural radiation and its possible harm to health, such as lung cancer, where radon gas is considered the second largest cause, is a growing concern of scientific communities and government agencies. This work aims to analyze the indoor radon gas concentrations in the municipalities of Carambeí and Curitiba, both cities in the state of Paraná, Brazil, compare it to the recommendations made by the ICRP and propose mitigating actions, with a view to lower exposure and risk to the health of the population. For the measurements, CR-39 solid state passive detectors were used, installed in homes for a minimum period of 90 days. Background detectors were used for control. After removing the detectors, a chemical treatment was performed and the manual contabilization of the nuclear tracks was performed using an optical microscope. Based on the methodology developed by the colaboration work of UTFPR and CDTN/CNEN, the tracks were counted and the average concentrations were calculated. The results showed that in Carambeí about 97% of the places had concentrations ranging from 95±15 Bq/m3 to 171±25 Bq/m3, within the recommendations. In this region, only one location showed 461±65 Bq/m3as concentration what suggests attention, generating the need for mitigating actions. The indoor cameras installed in the Santa Felicidade neighborhood in Curitiba – PR, presented a final result with concentrations ranging from 87±14 Bq/m3 to 143±22 Bq/m3, all values below the limit recommended by regulatory agencies and compatible with world average data. Given these results the fact that one site exceeds the recommended safety levels emphasizes the importance of mapping radon concentrations and the need to structure a national policy that establishes exposure limits in indoor environments in Brazil.