Radon is a colourless, odourless and tasteless radioactive noble gas that occurs everywhere in nature, albeit locally in very different concentrations. According to a letter from the Bavarian State Agency for Environmental Protection, radon and its decay products are the second most common cause of lung cancer after smoking (smoking 90%, radon 7%), according to other sources, there are currently about 2000 lung cancer deaths caused by radon in Germany every year.
Depending on the nature of the environment, the gas escapes from rocks and soils and usually spreads as soil air or in a dissolved state in the water near the surface. It penetrates into the building through cracks and joints in the floor slab and basement walls, but also through windows and pipe penetrations, and can spread to the upper floor, depending on the airtightness and nature of the building. In living rooms, the average radon concentration is about 50 becquerels per m³ of air. Depending on the nature of the subsoil, the condition of the building and the air exchange rate in the building, the measured values can range from a few to a few thousand becquerels per m³ (Bq/m³).
With the Radiation Protection Act (StrlSchG), the main parts of which will come into force on 31.12.2018, there is for the first time in Germany a legal reference value for the radon 222 activity concentration in the air averaged over the year: it is 300 becquerels per m³. The new Radiation Protection Act also regulates measures to protect against radon. This applies both to new construction projects of buildings with recreation rooms or workplaces, but also to structural changes to such buildings as well as existing workplaces indoors, see lexicon article ► < a href="https://www.bauwion.de/begriffe/radonschutzmassnahmen-gem.-strahlenschutzgesetz" target="_blank">radon protection measures in accordance with the Radiation Protection Act. Depending on the existing radon contamination, in certain cases the moisture protection provided anyway may already provide sufficient protection against radon or additional measures may be necessary.
Depending on the intensity of the load, suitable additional protective measures for new buildings range from waterproofing films under the floor slab and on the basement walls to tight basement windows to ventilation drains outside or controlled ventilation systems inside the building. In many cases, simple measures such as sealing the doors of basement staircases, sealing pipe/pipe ducts or exhaust air systems in basement rooms can reduce the spread of gas to the higher common rooms. Punctual leaks, such as pipe penetrations or small cracks, can be sealed with silicone, for example.
Because the gas penetrates mainly through the basement, its concentration decreases on each higher floor. The airtightness of a building, which makes sense from an energy point of view, can lead to increasing concentrations if there is insufficient ventilation. An important contribution to reducing the radon concentration indoors is therefore regular and sufficient ventilation in any case.
Source: bauwion
