Maximum levels and regulations concerning radon in dwellings

According to decision 944/92 of the Ministry of Social Affairs and Health, the radon concentration in indoor air in dwellings should not exceed 400 becquerels per cubic metre (Bq/m3). New dwellings must be designed and built so that the expected radon concentration does not exceed 200 Bq/m3.

The term radon concentration refers to the annual average level of radon, either measured or determined on the basis of measurement as the average radon concentration during a continuous period of twelve months. According to the Housing Health Instructions issued by the Ministry of Social Affairs and Health, radon concentration exceeds the annual average of 200 Bq/m3 if the concentration measured in winter (from 1 November to 30 April) exceeds 240 Bq/m3. Similarly, the annual average can be estimated to exceed 400 Bq/m3 if the concentration measured in winter exceeds 480 Bq/m3. Accurate determination of the annual average radon concentration requires 12-month measurement.

If the limit value of 200 becquerels in a cubic metre is exceeded in a new dwelling, the occupant can require reduction of the radon concentration as repair under warranty. Therefore, occupants of new flats should have the radon concentration measured as soon as possible after moving in, during the period of guarantee.

Regulations and guidelines concerning radon-safe construction work

  • Ministry of the Environment. Indoor Climate and Ventilation of Buildings, Regulations and Guidelines. 2012. D2 The National Building Code of Finland
  • Ministry of the Environment. Foundations, Regulations and Guidelines. 2004. B3 The National Building Code of Finland
  • Rakennustieto Oy. Radonin torjunta. RT reference card RT 81-11099, LVI 37-10513, KH 27-00510. (Radon prevention, available in Finnish)
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