Health effects of radon
The exposure to radon, a naturally occurring radioactive element that occurs in the natural decay series of uranium and thorium may constitute hazardous radiation exposure. The gas penetrates mostly from the underground in houses, under unfavorable conditions can make the radioactivity content of the indoor air to rise so much that a disease of the residents is to be feared from diseases such as lung cancer.
Influence of radon on humans
By the inhalation of radon, the risk of developing lung cancer increases. The reason for this is not the radon gas itself, but are also the resulting radioactive radon decay products. They are heavy metal atoms, which are deposited for the most part on the air and aerosol particles are deposited in the respiratory tract and accumulate. The occurring among the decay products alpha emitters irradiate the respiratory tract with biologically very active alpha particles. The largest probability at lung cancer is cancer, because the local radiation dose in the bronchi is the greatest.
For uranium miners lung cancer caused by radon, a recognized occupational disease. In the early days of the mining industry, it has become known as Schneeberger disease and has virtually killed all the miners in the area of snow mountain in the Ore Mountains.
Calculated estimates of the incidence of lung cancer of miners have shown that radon is responsible for about 10% of lung cancer deaths. This order of magnitude has now been confirmed by epidemiological studies. So go per year in the EU 20,000 lung cancer deaths in Germany and about 1,900 on radon back.
The skin is likewise exposed to the gas, but the epidermis as dying tissue is only slightly affected by the radiation and protects the underlying tissue from effective, because the alpha radiation has very limited penetration depth (range).
The stable element at the end of the radioactive decay chain is lead.
Load
The regional exposure to radon in the air is very different. This is due to the different occurrences of individual rock types and compositions. Regions where uranium was mined, and regions with granite, bauxite and black shale deposits have high radon concentrations in the soil, in the air and in water, higher than soils from calcareous rocks. In homes, the load is greater than in the free atmosphere, especially in basements, cellars with private wells and on the ground floor. In higher floors, the load is less. Houses made of natural stone or clay ( half-timbered house ) are loaded heavily.
From the renovation and modernization of existing objects, which are usually implemented with the goal of saving energy, significantly higher values of radon concentration may result as before construction when the radon problem is not observed when configuring. A structural waterproofing, for example, according to the German Energy Saving Ordinance, and the associated partly significant reduction of air exchange can lead to an increase in radon concentration up in areas where a significant risk to health. This mainly affects residents of houses that were built on land containing geologically conditioned elevated radon concentrations. Remedy against rising radon offers, for example, the installation of cavity elements ( PIRLS, etc.) in the bottom base plate, which are connected by pipes with the outside world. Thus both rising damp and radon or mine gases are passed safely to the outside.
The geogenic radon potential existing under a building can be determined by an examination of the subsoil. In this context, it is advantageous to determine before the erection of new buildings, the radon concentration in a meter deep in the ground.
For the problem of ventilation, there are now windows that have a small flap in the frame, which provides continuous ventilation with no wind. With stronger wind movement closes this door and the window is as close as a manufactured according to current guidelines conventional window. The seasonal variation in the house are associated with an altered ventilation behavior in the summer compared to the winter months. As well as the weather conditions are responsible for the variations. How can increase the radon concentration at a low exchange conditions.
In Germany the average radon exposure indoors is 59 becquerels per cubic meter of air. 1984, a study in West Germany a log- normally distributed load at a mean of 40 Bq/m3 in the room air.
In water there is also radon, which goes into this in the first contact with the air - on average in Germany 4.4 kBq/m3. While showering, the radon concentration in the air can increase to over 3000 Bq/m3. The radon concentration in buildings subject depending on the type of use of the building as well as the habits of the inhabitants fluctuations, which can be up to three orders of magnitude. The following are typical values of radon concentrations that are representative of the Federal Republic of Germany listed.
Explanation Example: 50 Bq / m³: In a cubic meter of air radon atoms disintegrate 50 per second.
Radon Protection Act
Europe
The European Commission recommends limiting the maximum radon concentration indoors. The following limits are recommended:
Intervention reference: 400 Bq/m3 applies to buildings that were built before 1996
Planning guideline: 200 Bq/m3 applies to buildings that were built after 1996
The Commission on Radiological Protection / noted in its opinion of 14 July 2004, a statistical significance of additional pulmonary risk from radon from 150 Bq m³. It is therefore a reduction in the radon concentration indoors to below 100 Bq / m³ recommended that a draft law leaves but still waiting.
Germany
The Federal Ministry for the Environment, Nature Conservation and Nuclear Safety had tabled a bill in March 2005, which should set limits on the concentration of radon in buildings. The target value of 100 becquerels per cubic meter of air for new and old buildings were planned. Because of the early federal election on 18 September 2005, the proposed legislation could not be completed and the draft legislation lapsed with dissolution of the Bundestag. In the following legislative periods (April 2012 stood ) were decided no law on this subject so far.
Switzerland
In the Radiation Protection Ordinance of 1994, the following limits for radon -222 were established: 1000 Bq / m³ for residential and lounges and 3000 Bq / m³ for work spaces. For new buildings, a guideline value of 400 Bq / m³ is considered.
Approximate
Radon is the decay product of radium -226 and thorium - 232. Their activity in building materials should be less than 260 Bq / kg ( 7 nCi / kg). If it is higher, good ventilation must be ensured that prevents an excessive accumulation of radon. As a guide, the radon flux should be ( the exhalation rate ) less than 2 Bq / m² h and the concentration in the air to be less than 50 Bq / m³.
Radon Manual WHO
The World Health Organization (WHO ) has issued in September 2009 a handbook on lung cancer risks from radon in indoor environments. Then Radon is a leading cause of lung cancer. The WHO calls to reduce risks among others, individual data subjects. Longer term, the population to be protected by precautionary construction measures and retrofits. According to the WHO 100 becquerels per cubic meter as a maximum allowable concentration of radon in new and existing buildings should apply.