Radon, radiation from

Total exposures vary considerably with human activities as well. Frequent flyers, for example, receive higher doses of radiation because the intensity of cosmic radiation is significantly greater at high altitude than it is at ground level. Residents in locations such as Montana and Idaho, where there are uranium deposits, receive higher doses of radiation from radon, one of the radioactive decay products of uranium. 

Lyons RG, Crossley PC, Ditchbum RG, McCabe WJ, Whitehead N (1989) Radon escape from New Zealand speleothems. Appl Radiat Isot 40 1153-1158... 

It should be noted that there is intense controversy as to the health effects of radiation doses below about 100 mSv per year. This estimate of 15,000 annual cancer deaths from indoor radon, as well as estimates of tens of thousands of eventual cancer deaths from Chernobyl exposures, is obtained by applying the linearity hypothesis. This hypothesis has been adopted by most regulatory agencies but is strongly contested by some scientists who believe it overestimates the effects of radiation at low dose levels. Of course, if calculations based on this hypothesis overestimate the deaths from indoor radon, they also overestimate the effects of potential radiation from a waste repository. 

Stranden E., Ulbak K., Edhwall H. and Jcnassen N., 1985, Measurement of Radon Exhalation from the Ground A Usuable Tool for Classification of the Radon Risk of Building Ground, Radiation Portecticn Dosimetry, 12, 33-38. 

Jonassen, N., and J.P. McLaughlin, Exhalation of Radon-222 from Building Materials and Walls, in Natural Radiation Environment III (T.F. Gesell and W.M. Lowder, eds.) pp 1211-1224, National Technical Information Center, U.S. Department of Commerce, Springfield, Va. (1980). 

Radon constitutes a serious problem because, being a heavy gas, it collects in such places as basements and mine shafts. When inhaled, radon decays in areas where little penetration is require to cause tissue damage. Radiation from a and (3 decay is not of a highly penetrating type, but inside the lungs it does not have to be in order to still cause damage. Table 15.10 shows several properties of the noble gases. 

The human body is equipped to deal with nominal levels of radiation doses. Background (natural) radiation from radon gas, cosmic sources, soil, and water produces an average dose of about 0.3 rem (0.003 Sv) per year.4 However, large doses of radiation generated after a terrorist attack can overwhelm the body s ability to repair damage, leading to stochastic or acute health effects. 

Ttie major hazard from radon stems from its radiation of alpha particles, even though alpha particles (helium nuclei) can be stopped by a sheet of cardboard. When Rn-222 is inhaled, it decays into lead-210, which is also radioactive, and because it not easily exhaled, it remains in the lungs for long periods, causing lung cancer. It is estimated that about 10% of all lung cancers are cause by radon. 

Annual human exposure to radiation in millirems (mrems). Note that although radon is radiation from the Earth, it is displayed as a separate category. 

Though other parts of my interviews were widely reported, I know of no case where the comparisons between radiation from radon in homes with radiation from nuclear power were included. They certainly never got national attention. For the media, nuclear power was the most dangerous source of radiation, and there was no way they were going to report otherwise—that would be like an attack on their religion. Of course this was a simple extension of their refusal to compare radiation from nuclear power with that from natural sources and medical X rays. 

I often wondered whether the reporters were afraid to include my points about nuclear power, or whether they were edited out at a higher level. In any case, the media and the public view radiation from nuclear power and from radon in homes as entirely different and unrelated subjects. I repeatedly explained to reporters that when a cell in our bodies is hit by radiation, there is no way for it to know whether that radiation originated from nuclear power operations or from radon, but somehow that explanation never got reported. 

Radioactive contamination as some background radiation from natural sources, such as radon, occurs in some regions of the world, but there is particular concern over the contamination of surface water and groundwater by radioactive compounds generated by the production of nuclear weapons and by the processing of nuclear fuel. Many of these areas have remained unrecognized because of government secrecy. 

That brings up the second thing, which is that there are acceptable levels of radiation. We are constantly bombarded with naturally occurring radiation from outer space and natural elements in the Earth. YouVe been bombarded with particles from radioactive decay since you were born. Of course, even naturally occurring radiation can be harmful. In my part of the country, it s wise to check the levels of radon underneath your home because its radioactive particles can cause health problems. 

In the troposphere the most important sources of ionization are radioactivity and galactic cosmic rays [60]. The former, which is due to , P, and Y radiations from thoron and radon, is dominant up to about one kilometer altitude. Above this height, as in the stratosphere, galactic cosmic ray ionization is most important. 

According to Styron et al., (1979) for a realistic assessment of the magnitude of release of radionuclides, special attention needs to be given to lead-210 and polonium-210 since they appear to have a large potential for significant environmental impact and have not received sufficient attention in trace-element studies for power plants. Another potentially important parameter in determining radiation exposure to man centres on disposal and utilization of coal ash and refuse. Lee et al., (1977) have suggested that emanation of radon-222 from ash disposal ponds will be the most serious radionuclide problem associated with increased use of coal. A potential hazard can be associated with the use of fly ash in cement and concrete blocks and in roadway construction. The radium-226 in these concrete blocks used for home construction may constitute an important source of radon-222 dose to the public. 

A solid-state nuclear track detector is a piece of special plastic which is exposed as the sensitive element in a radon monitor. The alpha radiation from Rn and RnD, which penetrates the surface of the plastic, causes radiation damage along the entrance path, as shown in the schematic in Fig. 9.26. Chemical etching of the plastic after exposure... 

Two types of track-etch monitor occur, open and closed types. In the open type, the SSNTD is not contained in a volume and is exposed to the air as a bare foil. This detector will register the alpha radiation from the Rn and RnD in the air, and the track density on the foil represents the sum of these activities. However, the Rn signal will be much larger than the signal from the RnD, except at very high levels of RnD (high F factor), and the track density has to be interpreted in terms of this ratio, which is typically unknown. In close monitors the SSNTD is enclosed in a closed container into which Rn diffuses through a filter. This prevents the entry of RnD and dust particles into the chamber, and the foil is then sensitive only to the alpha radiation from Rn and RnD formed in the container. There is a repeatable equilibrium between the isotopes in the container, and calibration provides the relationship between the Rn concentration and the track density on the foil. A typical track-etch radon monitor of the closed type is shown in Fig. 9.27. 

The electret ion chamber for radon measurement or E-PERM (commercial name) can be used to determine the long-term average Rn concentration over periods of one week to months, depending on the levels. The electret system, as any other ionization chamber, is sensitive to pressure variations, and corrections for this effect should be made. A major disadvantage is that the electret will also respond to radiation from external sources. When used in gamma radiation fields (in many situations) a duplicate set of monitors have to be exposed to be able to correct for the effect of the external gamma radiation on the radon measurement. 

Radon exhalation is the flux of Rn from surfaces of U-containing materials. In many instances, it is necessary to measure this flux to determine the source term of radon represented by the material (e.g. radon exhaled from tailings dams as a radiological impact on the public or from building materials used for houses, to determine the potential radiation hazard). There are various ways to measure this parameter. 

Lind and Bardwell have summarized the effects of radio-active materials on methane oxidation. Under the influence of the alpha radiation from radon the oxidation of methane proceeded completely to carbon dioxide and water. The oxidation took place in one step, and from the numerical relation between the number of gaseous ions produced and the methane molecules oxidized, the formation of triplet ion clusters was postulated as shown ... 

As much as 75 per cent of the theoretical oxidation based on the radiation was obtained. Selenium diethyl was found to accelerate the oxidation under the influence of alpha radiation from radon. 

Lind and Bardwell14 found that in the initial stages of the reaction between ethane and oxygen under the action of alpha radiation from radon the rate of reaction was nearly double that between oxygen and methane tinder comparable conditions, but that the velocity of reaction decreased sharply when the reaction was about 70 per cent complete. As in the case of methane, the yield of oxidation products was 75 per cent of the maximum theoretically possible on the basis of number of ions present. 

The oxidation of butane and propane under the influence of radiation from radon did not go to completion as indicated by the appearance of liquid products other than water.7 Prolonged exposure to the alpha radiation, however, gave complete oxidation in the case of propane. 

Current opinion is that there is a small risk to human health from even low levels of exposure to ionizing radiation, but there is also a known quantity of natural background radiation that the human species has always encountered. In 1984, an employee at a nuclear power plant began to set off radiation alarms while walking into the plant. An investigation found that his home contained high levels of radon gas from natural minerals. Radon tests are now routinely performed in many homes. 

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