科研之友
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摘要
Enclosed spaces in contact with soil, the main source of radon, like greenhouses have potentially high radon (Rn-222) concentrations. Greenhouses are frequented by visitors and also are workplaces. The study of radon concentrations in greenhouses is, thus, a relevant concern for public health and environmental radiation authorities. For this study, the radon concentrations in 12 greenhouses in different locations within Mexico City were measured using nuclear track methodology. The detectors used for the study consisted of the well-known closed-end cup device, with CR-39 Lantrack(A (R)) as detector material. The measurements were carried out over a period of one year, divided into four three-month sub-periods. The lowest and highest annual mean radon concentrations found in individual greenhouses were 17.0 and 45.1 Bq/m(3), respectively. The annual mean averaged over all 12 greenhouses was 27.3 Bq/m(3). No significant seasonal variation was observed. Using the highest annual mean radon concentration found in an individual greenhouse, and an equilibrium factor of 0.4, the effective dose from Rn-222 and its progenies was calculated to be 339.9 nSv/h. This corresponds to an annual dose rate of 679.8 mu Sv/y (0.057 WLM/y) for a worker spending 4 h a day, 5 days a week, 50 weeks a year, inside the greenhouse. For a visitor spending 12 h a year inside the greenhouse the annual dose is 2.469 mu Sv/y. The study of indoor radon concentrations in closed buildings such as greenhouses, which are both workplaces and open to visitors, is an important public health consideration.
- 出版日期2013-4
