The Risk from Radon

In a highly publicized case about 35 years ago, an employee reporting for work at a nuclear power plant in Pennsylvania set off the plant s radiation monitor. Astonishingly, the source of his contamination turned out not to be the plant, but radon in his home  

A lot has been said and written about the potential dangers of radon as an air pollutant. Just what is radon Where does it come from And how does it affect our health  

The half-life of Rn-222 is 3.8 days. Starting with 1.0 g of Rn-222, how much will be left after 10 half-lives  

Strategy All radioactive decays obey first-order kinetics, making the half-life independent of the initial concentration. 

Setup Because the question involves an integral number of half-lives, we can deduce the amount of Rn-222 remaining without using Equation 14.3. 

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Radon in indoor air may cause 14,000 cancer cases and secondary tobacco smoke may cause 3,000 cancer cases each year (USEPA 1993b). USEPA has developed effective methods to monitor and manage radon. They recommend that every home purchase a low-cost monitor to assess exposure and determine what control steps if any are needed. The risk from radon is increased by the presence of secondary tobacco smoke, which contains many toxic compounds such as PAHs and benzene (USEPA 1993b Wallace 1991). Thanks to public education about risks from radon and tobacco in the home, many families will no longer accept smoking inside the home. 

The lung cancer risk from radon daughter exposure is known only for occupationally exposed males. In order to determine the risk in environmental situations it is necessary to determine whether the bronchial alpha dose, which confers the risk, is similar to that in mines. 

Many states in the U.S. are currently involved in large scale surveys to measure radon levels in homes in an attempt to assess the environmental risk from radon and radon daughter exposure. Radon daughters deliver the largest radiation exposure to the population and it is estimated that 0.01% of the U.S. population (23,000 persons) are exposed from natural sources to greater than those levels allowed occupationally (4 WLM/yr) (NCRP, 1984). 

Because radon exposure varies widely from home to home, exposure information is a private rather than a public good, and a market developed to provide it. Basic information about the risks of radon exposure might be suboptimally provided by private markets, but the determination of exposure and the development of remediation plans are private goods that markets provide. 

Warner, Kenneth E., David Mendez, and Paul N. Courant. 1996. Toward a More Realistic Appraisal of the Lung Cancer Risk from Radon The Effects of Residential Mobility. American Journal of Public Health 86 1222-27. 

This chapter will predominantly deal with the risks from chemical contaminants but the reader should be aware that soils contain radioactive substances (e.g. radon) and a variety of biological pathogens (e.g. tetanus, anthrax) that can adversely affect human health. 

Table 3. Main factors influencing the radiation dose received by an individual following exposure to radon and daughters. Clearly, different individuals exposed to the same air would receive different doses. Broad models, based on the above parameters have been devised to assess average doses to average individuals for dosimetry purposes. Results from such models vary by factors of about 2 or 3, but this represents only one part of the sources of uncertainty in estimating risks from Radon exposure.

Extremely minute quantities of uranium occur widely in many types of rock and soil, and radon is found in all 50 states. The real risk from radon is derived from its products of natural radioactive decay, as damaging ionizing radiation in the form of alpha particles and other daughter products can be emitted. 

Public concern about risk ranges from earthquakes, fires, and hurricanes to asbestos, radon emissions, ozone depletion, toxins in our food and water, and so on. Many of the public s worries are out of proportion, because the fear is eidier overestimated or at times underestimated The risks given die most publicity and attention receive the greatest coiicem, while the ones diat are more familiar and accepted are given less thought. 

A less common entry mechanism is the outgassing of radon from well water. A well supplied by groundwater that is in contact with a radium-bearing formation can transport the dissolved radon into the home. It is estimated that the health risks associated with breathing radon gas released from the water are 10 times higher than the risks associated with ingesting water containing radon.9... 

Be sure that applicable codes and standards are followed Begin with the life and safety codes. The intent of this chapter is to reduce the risk resulting from radon, but not in a way that increases other risks. Especially important in this regard are the National Fuel Gas Code,58 National Fire Protection Code (NFPA1), and National Electric Code.59 Also the CABO One and Two Family Dwelling Code32 will be very helpful. There are thousands of code jurisdictions in the United States therefore many issues will have to be dealt with locally. 

The estimated risk from the observed radon distributions is such that a substantial fraction of the northeastern United States population is exposed to levels high enough to warrant immediate attention. 

James, A.C., Greenhalgh, J.R., and A. Birchall, A Dosimetric Model for Tissues of the Human Respiratory Tract at Risk from Inhaled Radon and Radon Daughters - A Systematic Approach to Safety, Proc. 5th Cong. IRPA, Jerusalem 1980, Perg. Press, Oxford, vol 2, 1045-1048, (1980). 

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 normal or average risk from whole body gamma-ray exposure in the environment is only about 10% of that from average radon daughter exposure and much less in elevated indoor environments. Considering that the radon daughter lung cancer risk can be derived directly from exposure in most cases, effective dose equivalent is an unnecessary step. 

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