| Summary: | 碩士 === 大仁科技大學 === 環境管理研究所 === 102 === Abstract
Sources of natural radiation in our surroundings include cosmic rays, terrestrial radiation, radon and radiation from the human body. The purpose of this study is to investigate the levels of environmental radiation in the elementary school campuses in Pingtung County and establish their background values, thereby providing reference data for campus health management. In order to compare differences between indoor and outdoor environments, different supervised areas, and different altitudes, 51 elementary schools in Pingtung County were selected for detection at locations including enclosed classroom, office, playground and school entrance in evry investigated school are selected as measurement points. Gamma responder, a system for rapid detection instrument for gamma ray manufactured by US-based RAE, was used as the research instrument. Detections were conducted at a minimum of six elementary schools in each of the supervised areas in Pingtung County. Measurement results show that the average level of environmental radiation (μSv/h) in enclosed classroom, office, playground and school entrance in all investigatory school campuses are 0.124, 0.118, 0.089 and 0.080, respectively. Overall, the levels of environmental radiation in these campuses have a maximum of 1.23 mSv/y and minimum of 0.53 mSv/y, neither of which exceeds the annual dose limit of 5 mSv/y recommended by the International Commission on Radiological Protection (ICRP) for the general public and both of which fall within the normal and safe background range of radiation level variation, confirming no safety concerns. The indoor environments have a mean value of 0.121 μSv/h, which is greater than that of the outdoor environments at 0.085 μSv/h. A paired sample t-test on the 51 pairs of data obtained from the indoor and outdoor environments indicates that a statistical significance level (P<0.001) is reached. The indoor-outdoor ratio range is 1.20~2.13, with an overall mean of 1.43, and is within the worldwide indoor-outdoor ratio range 0.6~2.3 provided in the report by the United Nations Scientific Committee on the Effects of Atomic Reaction (UNSCEAR). There is also no significant difference between the seven major supervised areas in the elementary school campuses in Pingtung County. The level of radiation in the outdoor environment tends to increase together with altitude. 92.2% of the highest radiation levels are detected in enclosed classrooms. Therefore, this study suggests that schools should open the doors and windows of the relatively enclosed classrooms regularly to avoid concentration accumulation of radiative radon air.
Keywords: Levels of environmental radiation,
elementary schools in Pingtung County,
indoor and outdoor,
altitude
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