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Worrying data exists from around the world on this radioactive gas: the NATIONAL ACADEMY OF SCIENCES estimates an annual mortality rate of 15,000 to 22,000 in the United States alone. In a country like France, where the concentration levels are around the European average, deaths from lung cancer caused by radon are estimated at 10%. In the United Kingdom, where the standard concentration is lower, lung cancer cases are actually higher and health authorities estimate that around 2000 lung-tumour deaths result from exposure to the gas per year.
Radon emanates from certain crops of rock in the earth’s crust as well as lava, tufa, pozzolan, and certain other granites. Although concentrations of this gas are usually higher in volcanic materials, sometimes high rates of radionuclides are found in sedimentary rocks. Therefore it is important to assess the likely risks linked to radon on a particular construction site, before a building work is started. , The precautions to be taken, should traces of radon be found, will then usually depend on the type of soil and subsoil.
In 95% of cases, radon contamination derives from exhalations in situ, and much more rarely the gas enters buildings through water pipes (1-2%). Such contamination is likely to emanate from radioactive building materials. Even perfectly ‘healthy’ building materials can contribute indirectly to the problem through design flaws or faulty planning (such as poor ventilation, inadequate soil insulation, etc.) which if done well can eliminate, or considerably reduce, radon’s effect on indoor air quality. |
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