[en] With 3-month simultaneous measurements of thoron and its progeny concentrations in the lowest floors of 109 homes, the geometric mean (GM) of thoron equilibrium factor was determined to be 0.019 with a geometric standard deviation (GSD) of 3.63. Combined with the analysis from results obtained from a previous study in 138 homes, the GM of thoron equilibrium factor was determined to be 0.022 with a GSD of 3.02. The results indicate that the F value of 0.02 for thoron recommended by UNSCEAR is a reasonable value for those Canadian homes tested. Published by Oxford Univ. Press on behalf of the Canadian Government 2011. (authors)

[en] This study has estimated the concentrations of radon gas and respirable ore dust in the Merelani underground tanzanite mines. Two different portable monitors were used to measure the radon gas and respirable ore dust concentrations respectively. The mean radon gas concentration (disintegrations per second per cubic meter) ranges from 40.1 Bq/m"3 to 4.2x10"3 Bq/m"3 with the geometric mean of 118.4 Bq/m"3 which is below the ICRP workplace guidance level of 500 – 1500 Bq/m"3. The estimated mean annual effective dose (D) was 1.6 mSv which is significantly lower than the external exposure annual effective dose of 20 mSv and the annual organ dose limit of 2.4 mSv. The overall concentrations of respirable ore dust arithmetic mean was 18.2 g/m"3 and the geometric mean of 2.1 g/m"3 which is very high compared to the guidance level of 2 g/m"3. The respirable dust was mainly produced during drilling and blasting of rocks, under normal conditions the geometric mean of respirable gas concentrations was 0.8 g/m"3. It is recommended that immediate intervention such as providing proper ventilation during the two processes to dilute radon levels in underground mines and the monitoring should be done regularly. (author)

[en] In the present work a set of indoor radon measurements was carried out in different dwellings in Baghdad governorate. Radon concentrations were determined by using time-integrated passive radon dosimeters containing (CR-39) solid state nuclear track detectors. Measurements were carried out during the months (July and August, 2013). The results show that, the radon concentrations varied from (27.250±4.1 Bq.m-3) to (79.500±1.5 Bq.m-3) with an average value (51.688±16.7 Bq.m-3) which is less than the lower limit of recommended range (200-300 Bq/m3) (ICRP, 2009). The values of the potential alpha energy concentration were found to vary from (2.946 mWL) to (8.595 mWL) with an average value (5.588±1.5 mWL) which is less than the recommended value (53.33 mWL) given by (UNSCEAR, 1993). The value of exposure to radon progeny vary from (0.354 WLMY-1) to (0.121 WLMY-1) with an average value (0.230±0.1 WLMY-1) recommended range (1-2 WLMY-1) by the (NCRP, 1989). The values of the indoor annual effective dose vary from (0.687 mSv/y) to (2.003 mSv/y) with an average value (1.302±0.4 mSv/y) which is less than the lower limit of the recommended range (3-10 mSv/y) (ICRP, 1993). The values of lung cancer cases per year per million person vary from (12.366) to (36.054) with an average value (23.443±6.1) per million person which is less than the lower limit of the recommended range (170- 230) per million person (ICRP, 1993). (author)

[en] The paper intends to outline the activities of the UNSCEAR and to summarize the content of its most recent report to the General Assembly. This purpose is made difficult by the very large amount of information it contains: only the most general conclusions will therefore be presented and the reader is referred to the original publication for a detailed description of the conditions under which such conclusions were derived. (orig.)

[en] After a short historical review, the goals of the ICRU are first presented: definition of quantities and units to be used in the field of ionising radiation, recommendations of measurement procedures for these quantities, definitions of terms and concepts, and investigation and selection of physical parameters. As far as the other international organisations are concerned, some of the main achievements are briefly presented for the IEC, UNSCEAR, ICRDP, WHO and IAEA. Besides technical developments and dosimetric intercomparisons, the importance of the education and of the continuous information of the radiologists is stressed. The role played by the CEC in education is recognised in the field of radiation protection in diagnostic radiology. (author)

[en] The author presents an outline review of his twenty five years' experience as a founder delegate and UK representative of UNSCEAR, from which post he retired in 1982. (U.K.)

[en] The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) continuously evaluates the worldwide levels of occupational radiation exposure for two broad categories of sources: natural sources of radiation and man-made sources of radiation. The UNSCEAR evaluation is based on data from the UNSCEAR Global Survey of Occupational Radiation Exposures conducted by formal request to all 192 Member States of the United Nations, supplemented with data from literature. The UNSCEAR evaluations need to provide information relevant for policy and decisions regarding the use and management of radiation. The UNSCEAR questionnaire is designed in order to obtain the basic data to evaluate the level of occupational exposure in each sector and sub-sector of work. Specific additional information is requested for each sector or subsector and category of worker; as well as information to evaluate the reliability of the data. The UNSCEAR questionnaire is in good agreement with currently updated national databases. Since these databases for occupational exposure are the main source of information for UNSCEAR, they need to be regularly updated in order to reflect any change on the level of occupational radiation exposure when new technological developments and modifications to work practices occur. (author)

[en] This paper provides the update of the reference dose distribution proposed by G.A.M. Web and D. Beninson in Annex E to the UNSCEAR 1977 Report. To demonstrate compliance with regulatory obligations regarding doses to individuals, they defined it with the following properties: 1) The distribution of annual doses is log-normal; 2) The mean of the annual dose distribution is 5 m Gy (10% of the ICRP 1977 dose limit); 3) The proportion of workers exceeding 50 m Gy is 0.1%. The concept of the reference dose distribution is still important to understand the inherent variation of individual doses to workers controlled by source-related and individual-related efforts of best dose reduction. In the commercial nuclear power plant, the dose distribution becomes the more apart from the log-normal due to the stronger ALARA efforts and the revised dose limits. The monitored workers show about 1 m Sv of annual mean and far less than 0.1% of workers above 20 m Sv. The updated models of dose distribution consist of log-normal (no feedback on dose X) ln(X)∼N(μ,σ²), hybrid log-normal (feedback on higher X by ρ) hyb(ρX)=ρX+ln(ρX)∼N(μ,σ²), hybrid S_B (feedback on higher dose quotient X/(D-X) not close to D by ρ) hyb[ρX/(D.X)]∼N(μ,σ²) and Johnson's S_B (limit to D) ln[X/(D-X)]∼N(μ,σ²). These models afford interpreting the degree of dose control including dose constraint/limit to the reference distribution. Some of distributions are examined to characterize the variation of doses to members of the public with uncertainty. (author)

[en] The objective of this study was to measure indoor radon concentrations in the expected high risk area around Ipoh in Kinta Valley, Perak. The area was chosen based on its own special characteristics. The measurements were carried out by means of long term exposure (3 months) using CR-39 solid state nuclear track detector. The mean indoor radon concentration in Ipoh was 45 Bq/ m"3 which is equivalent to effective dose of 1.1 mSv/ y. This value was higher compared to low or normal area in Bangi, Selangor but comparable to the world average value reported by UNSCEAR. The maximum value of indoor radon concentration measured was 87 Bq/ m"3. (author)

[en] A report is given of the most recent assessment of doses from medical exposures published by UNSCEAR in 1982. Medical irradiation is characterised by the high instantaneous rate of exposure, by the fact that it generally involves limited parts of the body and by the large variability of the doses received by the patients. Under such conditions, expressing the doses as averages over the whole exposed population has little significance; on the contrary, collective doses may provide some indication of the overall impact of medical sources. It is estimated that the annual collective effective dose equivalent from medical diagnostic procedures may amount to about one-half of that received from natural sources in developed countries. In developing countries the same quantity could be ten times lower in view of a correspondingly lower rate of examinations. Thus, the annual collective effective dose equivalent applying globally over the whole world could amount to about one-fifth of the collective dose equivalent from natural sources. (author)