Radon is formed naturally in the soil and then rises and passes through the ground surface. Radon gas normally dissipates quickly into the atmosphere and therefore does not represent a danger to health. But when radon penetrates into enclosed spaces such as residences or mines, radon can reach high levels and represent health risks to those present. The extent of health risks depends on exposure i.e. on radon levels and exposure time to such levels, in addition to the fact that a combination of long-term exposure to radon and tobacco smoke increases such risks. It is estimated that about 30 000 people die of lung cancer caused by radon each year in EU. The average risk is therefore greater than the risk of dying in a traffic accident.
Radon is a radioactive inert gas that has its origins in uranium. It occurs in small or large quantities in the ground, so-called ground radon, which is the most common cause of radon problems in indoor air. Radon can however come from construction materials such as blue concrete, which is the cause of such problems in Sweden. It was used as a construction material between 1929 and1975 and contains alum shale. Blue concrete can have high or low emissions depending on where the shale was extracted from.
The risk of contracting cancer rises with increased exposure to radon. The Swedish Radiation Safety Act of 2018 specifies the reference value for radon at 200 Bq/m³. Since radon is odourless and invisible, measuring is required to detect the gas, and this is performed by Eurofins Radon.