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The basements of large hospitals in Taiwan are usually working areas for image radiometry, radiation therapy, and nuclear medicine, where the radon concentration can be accumulated. This study investigated radon concentrations in the basement working environments of 30 hospitals in different regions with various geology of Taiwan, aiming to explore the relationship between geological conditions and radon concentrations and estimate the radiation dose received by the working staff. Portable MR107+ semiconductor radon detectors calibrated with a radon chamber were used for radon measurement at the hospital basement working areas according to the protocol of MAH-2019 instrument placement recommendations from the US EPA. The excess lung cancer risk (ELCR) as well as the lung cancer cases per million persons (LCC) were further derived from the radiation dose. The basement working areas investigated are located on the first to sixth underground floors of hospitals in Taiwan mainland and islands, Penghu and Kinmen. The 222Rn concentration higher than 100 Bq/m3 was observed at CH-1 (122.1 Bq/m3) in Changhua City and CY-1 (114.7 Bq/m3) in Chiayi City. This is attributed to that the central air conditioning systems of these hospitals were turned off during off-duty hours. The radon concentrations of all hospitals were lower than the action level, 150 Bq/m3, regulated by the US EPA. No significant relationship was found between radon concentration and the geological characteristics of the measured sites. That is, the ventilation of the basement working areas in hospitals is more important than local geological characteristics on indoor radon concentration, and therefore proper ventilation is crucial for reducing radon gas concentration in the hospital basements. Estimated annual effective dose from 222Rn for the hospital staff was higher than 1 mSv/y at YL (1.24 mSv/y), CH-1 (1.64 mSv/y), CY-1 (1.54 mSv/y), CY-2 (1.34 mSv/y), and PH-2 (1.14 mSv/y), and that for the rest sites was <1 mSv/y. The maximum mean ELCR was found to be 0.63% at CH-1, and the related LCC was estimated to be 29.5 per million persons. • Higher radon levels were observed in hospital basements after the air conditioning systems were turned off. • Proper ventilation is crucial for reducing radon concentration. • No apparent effect of geological characteristics, temperature and humidity was observed on radon concentration. • Radon levels in all hospital basements were lower than the action level of US EPA. [ABSTRACT FROM AUTHOR]

Uranium- and thorium-series isotopes are able to dissolve in hot spring waters and decay into radon, which could potentially cause health risk of the public. Besides, several environmental investigations can be carried out by measuring radon concentrations in hot spring waters. Accordingly, the measurement of radon in hot spring water is a significant issue. A practical method for measuring radon in hot spring water was developed by using a silicon semiconductor detector, RAD-7. The overall effect of detection efficiency and radon leakage of the measuring system were examined to calibrate the measured concentration of radon in hot spring waters. In addition, the effect of water temperature and pH on emanation of radon from standard 226Ra solutions as well as that of the measuring time on precision of the measurement were investigated. The correlation among temperature, pH and emanation of radon was then obtained. Further, the established method was applied to in-situ measurement to investigate the concentration of radon in hot spring waters from different geological areas in Taiwan. According to the percent error of the measurement, the measuring time for environmental samples was set as 50 min. The overall effect of radon leakage and detection efficiency of the measuring system was estimated to be 99.19 ± 7.47% with a standard rock source of 222Rn from NIST. Standard sources of 222Rn were prepared from 226Ra standard solutions with different pH values. The 226Ra standard solutions were sealed and stand for 38 days in a 250 mL vial specific for the RAD-7. After measured by the WAT250 mode of the RAD-7, the data were measured as (52.5 ± 8.9)%∼(83.6 ± 11.0)% of the prepared concentration of 222Rn (from 226Ra). The emanation rate of 222Rn from standard solution under pH 1.44–9.07 was (53.2 ± 6.9)% ∼(84.3 ± 11.1)% and decreased with pH to a minimum value at 7.00. Moreover, the effect of temperature increases with pH. High correlated trend curves (r2 = 0.9829–0.9999) for 222Rn emanation rate versus pH under different temperature were obtained. A smooth curved surface fitted by the MATLAB for emanation rate of 222Rn was accordingly derived. The 222Rn concentrations in waters of the Beitou Hot Spring (acid-digestion sulfate spring on sedimentary rock strata), Wulai Hot Spring (sodium bicarbonate spring on metamorphic rock strata), Choshuitan (sodium bicarbonate spring on mudstone strata) and Zhaori Hot Spring (acid-digestion sulfate spring on andesite strata) were measured with RAD-7 by WAT250 for 50 min and then calibrated by 222Rn emanation rate estimated above, which were 215 ± 37 (Bq/m3), 6797 ± 1073 (Bq/m3), 2124 ± 577 (Bq/m3) and 26644 ± 2768 (Bq/m3). • A practical method for measuring Rn in hot spring water was developed. • Correlation among water temperature, pH and emanation of Rn was obtained. • A smooth curved surface fitted by the MATLAB for Rn emanation was derived. • This method was applied to in-situ measurement of Rn in hot spring waters in Taiwan. [ABSTRACT FROM AUTHOR]

The Geothermal Valley Hot Spring Area of Beitou in Taiwan is celebrated for is discovery of hokutolite. Ascribed to abundant radioisotopes of uranium- and thorium-series from igneous stratum in this area, the radioactivity and background radiation is important to be investigated for nearby inhabitants. In this study, measurements were carried out for gross α/β activities, radium-isotope and tritium activities in water, major naturally occurring radionuclides in soil, sludge and plants, and radon-isotope activities in air. The ambient dose rate, effective dose rate, direct radiation dose from surface of the ground as well as the annual effective dose to the public was estimated. Gross α/β activities detected in hot spring water indicated that the hot spring water is undrinkable in this area. Gamma activity in water was mainly from daughters of 228Ra and 226Ra, which decreased downstream the Beitou Creek. The activity of 3H was lower than the minimum detectable activity (MDA) at the sampling sites. The 7Be and 137Cs were rare in soil. Potassium-40 was measured in sludge, and 7Be and 4K were found in plants. Cobalt-60 was