OBJECTIVE: The objective of this study was to perform a passive and time-integrated radon monitoring in several soil and water samples and indoor environments of the São Vicente, SP, rock massif with the purpose of evaluating the presence and distribution of that radioactive gas in this region. MATERIALS AND METHODS: The technique employed consisted of exposing Makrofol E-type polycarbonate plastic detectors (SSNTD), using the closed cup method, to radon emanated from ground water samples and to the gas accumulated inside indoor environments (dwellings) and inside rock cavities existing in the São Vicente rock massif. RESULTS: The radon concentration values obtained ranged from 8.1 to 36 Bq/l in natural ground waters; between 68 and 610 Bq/m³ in dwellings; from 0.41 to 3.46 kBq/m³ in soils and from 0.72 to 5.85 kBq/m³ inside rock cavities of the São Vicente rock massif. CONCLUSION: In some dwellings and in most of ground water samples, the radon concentration values found in this study have exceeded the maximum levels proposed by international agencies. Thus, intervention actions are recommended for radon dissipation in dwellings and during consumption water collection.

Keywords: Radon, Natural radioactivity, Nuclear track detectors, Environment, Uranium

OBJECTIVE: Exposure to high levels of radioactive radon gas can cause lung cancer, therefore, it is important to measure the concentration levels of this gas in indoor environments in order to provide radiological protection for the general population. In this study, passive and time-integrated radon monitoring was performed in different types of indoor environments in Baixada Santista, São Paulo, Brazil including tunnels, fertilizer shops, shopping malls, ceramics shops and houses to evaluate the actual radon levels in these locations. MATERIALS AND METHODS: Radon concentration measurements were performed using the alpha particle track registration technique in plastic foils of Makrofol E, employing the closed cup method. RESULTS: Concentration levels of radon measured in the indoor environments studied ranged from 17 to 263 Bq/m³, which is in accordance with the values reported in the literature by other authors for similar environments. CONCLUSION: In general, the results obtained were below the maximum limits recommended by the International Commission on Radiological Protection (ICRP) and thus, intervention actions for the these locations were not necessary.

Keywords: Radon, Uranium, Environment, Nuclear track detectors