Questions & Answers - CCR
Radon is a noble gas and is produced by the underground decay of uranium. Being a gas, it can be breathed in homes, where it easily penetrates through non-airtight spots in the building. The further decay of radon into lead, polonium and bismuth releases radioactivity, which can irradiate lung tissue and cause cancer. In Switzerland, radon accounts for about 40% of the annual radiation load.
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In Switzerland, 8.5% of lung cancer cases are attributable to radon. Every year, radon causes 240 deaths and is thus the second most common cause of lung cancer, after smoking. Radon is the most dangerous carcinogen in the residential sector, but can be protected against with appropriate building measures.
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Ores containing uranium and thorium release radon. A radon measurement is recommended.
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No, there is no causal relationship. There is evidence that living in a house with a high radon concentration increases the risk of developing lung cancer, but no other health consequences are known.
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The radon concentration in a building decreases as a function of its height. Normally, radon levels are lower on the upper floors. As a general rule, a dwelling's radon concentration is considered negligible from the second floor upwards.
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The general rule applied to the problem of radon in dwellings is: no two dwellings are the same. Only a measurement can provide an answer. There are adjoining dwellings that have distinctly different radon concentrations.
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Dosimeters can be ordered from recognised radon measurement services. They are installed in inhabited rooms for three months, after which they are sent to the measurement service for analysis.
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The owner of the building can tell you whether measurements have already been taken and what the results were. Maps of areas with high radon concentrations can be consulted at the cantonal radon contact service.
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The results of the measurements are reported to the relevant cantonal radon contact service and to the Federal Office of Public Health.
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In Switzerland, a reference value of 300 Bq/m3 applies for living quarters. This value is exceeded in about 50’000 to 100’000 dwellings, which must be remediated in order to exclude the risk of serious damage to health.
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No, the mitigation of a radon-contaminated dwelling does not increase its value and consequently cannot be charged against the rent. Under Article 256 CO, the landlord has a general obligation to deliver the property in a suitable state. Exceeding the radon limit value poses a health risk. Within the meaning of this article, a serious defect can therefore be attributed to the dwelling.
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At the request of the tenant, the owner of a building is required to measure the radon concentration, but only if there is reason to believe that the 300 Bq/m³ reference value has been exceeded. This is the case, for example, with buildings located in areas of high radon concentration. In this case, the owner is obliged to carry out the measurement and report the results. If the owner refuses to do so, the competent Cantonal office must order a measurement. If the reference value is exceeded, the owner of the building is obliged to mitigate it.
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Airing has a temporary effect: after the windows are closed, radon concentration returns to their previous level.
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Radon exhales from every soil, albeit in highly variable quantities. In areas with a high radon concentration, building measures should be taken to prevent radon penetration. Unfortunately, a preliminary measurement gives no indication of the future radon concentration in living spaces. A map showing the probability [%] of exceeding the reference value of 300 Bq/m3 of radon concentration in buildings is available at www.ch-radon.ch.
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Exceeding the radon limit value represents a defect in the purchased dwelling, since the health risk caused significantly reduces its suitability. The seller is liable for these defects even if he was not aware of them. Nevertheless, contracts of sale of land often contain a disclaimer in favour of the seller. In such a case, the seller is liable only if he has knowingly concealed the defect.
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In new buildings, a jointless, hermetically insulated concrete slab already offers excellent protection against radon. In areas with a high radon concentration, ventilation under the foundations is also recommended. In addition, the installation of ducts and ventilation systems must be carried out carefully. If you are building a new house, you might want to discuss the issue of radon with your architect.
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Simple mitigations are possible for as little as a few hundred francs. More complex renovations, on the other hand, can cost several tens of thousands of francs.
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