UNSCEAR

RBE is used to denote the experimentally determined ratio of the absorbed dose from one radiation type to the absorbed dose of a reference radiation required to produce an identical biologic effect under the same conditions. Gamma rays from cobalt-60 and 200-250 keV x-rays have been used as reference standards. The term RBE has been widely used in experimental radiobiology, and the term quality factor used in calculations of dose equivalents for radiation safety purposes (ICRP 1977 NCRP 1971 UNSCEAR 1982). RBE applies only to a specific biological end point, in a specific exposure, under specific conditions to a specific species. There are no generally accepted values of RBE. 

UNSCEAR. 1977. United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and effects of ionizing radiation. New York United Nations. 

In order to compare exposures to radon decay-products with those to other forms of ionising radiation, it is useful to assess the effective dose equivalent expressed in sieverts (Sv). A conversion coefficient of 15 Sv per J h m"3, equivalent to 5.5 mSv per WLM, has been recommended (UNSCEAR, 1982). With this conversion factor, the... 

Diurnal Patterns. Radon and its daughter products are known to follow typical diurnal patterns in the outdoors with high levels in the early morning and lower concentrations in the afternoons (Gesell, 1983 UNSCEAR, 1982). Seasonal variation is subject to a variety of geographic and meteorological influence and does not fit a clear-cut pattern. 

UNSCEAR, Ionizing Radiation Sources and Biological Effects. United Nations, New York, NY (1982). 

Some years ago it was realized that the indoor inhalation of the short-lived radon daughters constitutes the most important contribution to the radiation exposure of the general population (Unscear, 1982). The working level concept has been introduced in the domestic environment due to the success of the concept in the occupational environment and due to a lack of experimental data on the relative and absolute magnitudes of the transformation and... 

The risk of lung cancer from exposure to radon daughters in homes is derived by assessing lung dose, either absolutely by evaluating an effective dose equivalent (UNSCEAR, 1982 NEA, 1983) or by scaling the... 

The range of doses calculated when only basal cells are assumed at risk is also shown in Figure 5. For unattached daughters, doses are approximately one half and for attached daughters three quarters of values derived by averaging over all cells. These doses are to be compared with the range derived by the NEA (NEA, 1983). The reference values recommended by the NEA and adopted by UNSCEAR (UNSCEAR, 1982) lie at the bottom of the range of doses to basal cells derived here. 

In the past, it was thought that building materials were the principal sources of indoor radon (UNSCEAR, 1977). However, most recent studies have shown that with the exception of some unusual materials such as Swedish alum-shale concrete, the effect of building materials on indoor radon is small. 

Figure 32.3 The three still-existing natural decay series. A. Uranium-238 B. Uranium-235 and C. Thorium-232. (Modified from Holtzman 1969 LWV 1985 UNSCEAR 1988 Kiefer 1990 Rose etal. 1990). Principal decay products occur within the heavy borders outlined.

Figure 32.6 Chernobyl air plume behavior and reported initial arrival times of detectable radioactivity. Plume A originated from Chernobyl on April 26, 1986 Plume B on April 27-28 and Plume C on April 29-30. The numbers indicate initial arrival times 1, April 26 2, April 27 3, April 28 4, April 29 5, April 30 6, May 1 7, May 2 and 8, May 3. (From United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). 1988. Sources, Effects and Risks of Ionizing Radiation. United Nations, New York. 647 pp.)... 

Data from United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). 1988. Sources, Effects and Risks of Ionizing Radiation. United Nations, New York. 647 pp. Aarkrog, A. 1990. Environmental radiation and radiation releases. Inter. Jour. Radiation Biol. 57 619-631. 

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