Indoor radon must be taken into account in the construction of new buildings everywhere in Finland. The easiest and most affordable way to prevent radon is to take measures at the construction stage. Methods for radon prevention include the installation of radon pipes and selecting a type of foundation that is radon-safe.
According to a decision (944/1992) of the Ministry of Social Affairs and Health, the radon concentration in indoor air in dwellings should not exceed 400 becquerels per cubic metre of air (Bq/m3). New dwellings must be designed and built so that the expected radon concentration of indoor air does not exceed 200 Bq/m3. The reference levels will likely be reduced on the basis of the new radiation legislation to be introduced in 2018.
Radon is easy to measure
The radon concentration in indoor air can only be detected through measurement. The measurement is carried out with the use of radon measurement boxes. A comprehensive assessment of exposure is achieved when two radon measurement boxes are used in different rooms and/or floors of a dwelling. The boxes are placed at a height of one metre in the bedroom or living room or another part of the dwelling, and they should stay in place for at least two months between early November and the end of April. The box or boxes are returned to the service provider, and the contents are used to analyse the radon concentration of the indoor air.
Radon mitigation at home
The aim of radon mitigation is to prevent air with high radon concentration from flowing from the soil to the indoor air. The mitigation method depends on the radon concentration measured in the indoor air, the soil under the building, the backfill, the structures of the house, and the ventilation system.
The most efficient methods for radon mitigation are sub-slab suction and radon wells, which create underpressure in the soil, preventing radon from entering the indoor air through the cracks in the base floor. Other means to reduce radon concentration in indoor air include ventilating the crawl space, sealing the base floor and improving ventilation.