An Environmental Risk Assessment of Radon in Lantian Karst Cave of Shaanxi, China

Abstract

The radiation dose and environmental health risk of radon concentration in the Lantian karst cave of China to guides and visitors were estimated based on the continuous radon concentration monitoring. Distinct seasonal variations were observed in the radon concentration of the air inside the cave. The maximum concentration occurred in the summer, whereas the minimum radon concentration occurred during the winter. The annual average radon concentration in the caves investigated is slightly higher than the upper bound of radon action level for underground space used in China and less than the upper bound of radon action level recommended by the International Commission on Radiation Protection (ICRP) for workplaces. The annual effective dose to tour guides working in two investigated caves varies from 4.1 to 16.5mSv, depending on different equilibrium factors together with different dose conversion factors proposed in the literature. The annual maximum time that a tour guide or other worker can safely be inside the cave is estimated to be 1,250 or 2,246h, depending on whether one bases this on the high or mean radon concentration, with an equilibrium factor of one in both cases. Given the synergistic effects of smoking, tour guides who are smokers should be in the cave only 10-20% of these hours. In all cases, the annual effective doses to visitors are well below the 1mSv maximum suggested dose for a member of the public for 1 year.

Natural radioactivity, radon exhalation rate and radiation dose of fly ash used as building materials in Xiangyang, China

“…1,3,4 The indoor annual exposure effective dose of 222 Rn ( E Rn ) released from fly ash was calculated using equation (6). 1,3,4,11 Where C Rn is the 222 Rn concentration (Bq m −3 ) released from fly ash, n is the fraction of time spent indoors taken as 0.8, 8760 is the number of hours per year, F is the equilibrium factor and DCF is the dose conversion factor, expressed in mSv WLM −1 .…”

“…1,3,4 The indoor annual exposure effective dose of 222 Rn (E Rn ) released from fly ash was calculated using equation ( 6). 1,3,4,11…”

“…222 R, 220 Rn and 219 Rn, of which half-lives are 3.82 days, 55.6 and 3.96 s, respectively. 11,12 Amongst the three isotopes, 222 Rn has the most significant impact on the environment due to its relatively long half-life, enabling it to migrate quite significant distances within the geological environment before decaying. 222 Rn is a radioactive extremely inert gas which is derived from the radioactive decay of radium ( 226 Ra), a decay element in 238 U series.…”

Analysis of Radon Mass Exhalation in Soil Samples from Fault Regions of Kolasib District Mizoram, India

“…Radon is gas formed on the fourteenth step of sequence of 238 U radioactive decay series and is being continuously formed in the soil and released in air. This radon gas released in the air occupies 43% of radiation received by human beings and is usually the reason of lung cancer [1][2]. The movement of radon inside the soil is called emanation where radon is released into small air or water contained in pores between soil and rock particles and when it arrives at the soil surface it exhales into the atmosphere.…”

Seasonal variation of radon and CO2 in the Važecká Cave, Slovakia

“…The radon activity concentration in the atmosphere of the karst systems depends on a complex interrelation among several different factors, including outside-inside temperature differences, the degree by which outside air mixes with cave air, humidity of the cave interior, precipitation amount and its infi ltration to the cave environment, 226 Ra content in host rock and cave sediments, rock and cave sediments porosity, 222 Rn exhalation rate from the surfaces in the cave, and volume and shape of the cave [1,[5][6][7][8]. Meteorological conditions are considered as a major infl uence on radon variability in the rock environment.…”