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Norwegian Radiation and Nuclear Safety Authority

Radon and health risks

According to the World Health Organization (WHO), radon is the most important cause of lung cancer after active smoking. 

Last updated: 19. mars 2021 11:05


  • It is estimated that radon in homes causes around 300 lung cancer deaths a year in Norway.

  • The risk increases with the radon concentration in the indoor air and with the time spent indoors.

  • To reduce the risk in existing buildings, radon-reducing measures can be implemented.

Radon is present in all kinds of buildings and the total radon risk is determined by the sum of the time spent in different buildings; at work, at home and in leisure time. 

Why is radon dangerous?

When radon is present in air, several short-lived radionuclides called radon daughters are continuously formed. Both radon and radon daughters emit alpha radiation and can damage living cells, causing some to develop into cancer cells.

Alpha radiation is easily blocked in the air and does not penetrate the surface of the skin, but if inhaled, it can increase the risk of developing lung cancer. Radiation doses to organs other than by absorption via the lungs are very small and can usually be ignored. 

Risk of getting lung cancer

Radon increases the risk of lung cancer. The risk increases with exposure and is proportional to the indoor radon concentration and the exposure time. There is no threshold dose for when radon starts to constitute a health hazard. The risk is highest for people who actively smoke or have smoked. The risk of radon exposure is around 20 times greater for smokers than for people who have never smoked, but there is also a significant risk to non-smokers. 

To reduce the risk in existing buildings, radon-reducing measures can be implemented. For example, halving the radon level also halves the risk of developing lung cancer caused by radon. 

Strategic goals

DSA’s overall goal is to substantially reduce the number of cases of lung cancer caused by exposure to radon in Norway. In order to achieve this goal, DSA has adopted a strategy whereby radon concentrations in all types of buildings and premises in Norway must be as low as reasonably achievable and below the stated limits.

DSA’s aims are:

  • A reduction in the overall radon risk to the general population  
  • Individual radon risks for individuals reduced to acceptable levels 

This twofold objective is based not only on cost-effectiveness, but also on ethical considerations. From an ethical perspective, it is important to address the need to minimise individual risk while also pursuing the general aim of reducing the number of radon-induced cancer cases in society as a whole.

Relevant information 

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