Is there radiation in my home?
If you want a short answer, it is yes. There are many kinds of radiation in every home: light, infrared, ultraviolet radiation, and even radioactive radiation from both outside and from our own body. In fact it is not important whether the answer is yes or no – just as in many other environmental questions. The important point is what kind of radiation and how much.
The risks of radon
From the standpoint of human health the most important kind of indoor radiation source in many countries is radon. It is Noble gas originating from uranium in the bedrock. Granite is one of the rock types emitting radon, and therefore in some countries like Finland, one half of natural radiation is due to radon and its radioactive daughter elements. There is a lot of information on the risks of radon on lung cancer as far as mining is concerned. In mines, the radon concentrations may be hundreds of times higher than that found in any home. This is not only in uranium mines but it applies to all mines. The risk of cancers other than lung cancer is not elevated in miners.
The risk of indoor radon in homes was unclear for a long time. This is because the concentrations are much lower than in mines, and normal people’s exposure is much more difficult to assess afterwards than that of mine workers. The development of cancers takes many years, and the current radon exposure is not necessarily a good measure of our lifelong exposure. Moreover, smoking is an important confounding factor making the studies difficult to interpret.
During the last few years, several large studies have been published. The results seem to agree with the mining studies, and in the Nordic countries, radon is estimated to be responsible for about 10 % of all lung cancer, hundreds of cancers in each country. Uncertainty has been relatively large, but it was decreased when the results were published of a very large European study comprising over 7000 lung cancer cases and 14,000 controls. This study indicates that there are thousands of lung cancers every year in Europe attributable to radon.
Sources of radon
Radon is a Noble gas which is one of the fission products of uranium in the bedrock. It is completely tasteless, odourless and invisible and thus it cannot be detected without professional equipment. The cancer risk of radon is not due to radon itself, but attributable to short-lived fission products in the inhaled air, e.g. lead and polonium isotopes emitting alpha particles. The fission products become attached to small dust particles which are transported to the lungs and may stick to the surfaces of airways. The radiation consisting of alpha particles is very destructive to human cells, but it can travel only short distances. Therefore, the effects are limited to the lungs.
There can be huge variations in the indoor radon concentrations depending on the region. Many regions in the Nordic Countries are high-exposure areas because of the granite bedrock. The gas passes easily to the surface through surface soils. In addition, changes in construction technology have favoured high radon exposures. The previous construction tradition of a leaving ventilated space under a building allowed venting radon away. The present way of constructing directly on the soil surface lets radon pass directly to the homes, especially those living on the ground floor. If there is reduced air pressure due to mechanical ventilation in the building, this will suck up radon from the soil.
During the last years more emphasis has been placed on removing the risks of radon. This can be best and most cheaply achieved before the construction of the building. The key is ventilation below the building in radon-rich areas. In old buildings, the repair may be more expensive; the basic idea is to let radon escape from under the building before it has a chance to enter the structure. This may be achieved by various piping systems and pumps.
Radon is one of the most important sources of natural radiation which can affect your health. It is probably responsible for over a thousand cancers in the Nordic countries alone. In radon-rich areas, concerns about other sources of radiation are meaningless, unless radon is not being eliminated.
Finland was one of the countries with the highest exposures to radioactivity after the Chernobyl accident. Some parents of exchange students considered bringing their children back home from Finland after the accident, and even some Finns thought of leaving the country. In reality, the continuous radon exposure in Finland has been a much more important cause of concern than any radioactive fallout.
The risks of radiation are difficult to put into perspective, and even the relative importance of different types of radiation is often not understood at all. Natural radon is one of the major radiation risks in many countries.
Notes and references
- See also the chapter "Which type of radiation poses the greatest threat to our health?"
One level up: The air that we breathe
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