Can radon gas cause cancer?

  • Radon is a natural radioactive gas that can build up indoors. If indoor radon builds up to high levels, it can increase the risk of lung cancer.

  • But most radon-related lung cancers are caused by the combined effects of smoking and indoor radon gas.
  • Levels of indoor radon gas in most UK homes are low, but some may have higher levels.

What is radon gas?

Radon gas is a natural radioactive gas that comes from rocks and soil. It’s found in the air at low levels outdoors, but can sometimes build up to higher levels indoors. When this happens, it can slightly increase the risk of lung cancer.


How does indoor radon gas cause lung cancer?

Radon gas gives out radiation. When we breathe it in, the radiation can cause changes to the cells in our lungs and airways. This damage can lead to cancer.

Most cases of lung cancer in the UK are not linked to radon gas. And most of the cases that are linked to radon gas could be prevented by not smoking.

There is some evidence that radon and smoking increase each other’s effects on cancer risk. So, radon exposure will have a bigger effect on the cancer risk of someone who smokes than it would on someone who doesn’t.

This means that not smoking is an important way to reduce the risk of lung cancer caused by radon.

Find out how to stop smoking


What are the levels of radon gas in the UK?

Most homes in the UK have low levels of indoor radon, so there’s usually no need to do anything about them. There are some changes to buildings that can reduce build-up of indoor radon, but they’re often expensive and there are more impactful ways to reduce cancer risk. Radon levels naturally vary in different parts of the UK, and between one building and another.

If you’re still concerned about radon, the website UKRadon has maps showing radon levels across the UK and information on how to test indoor radon levels. You can also contact your local authority for information.


International Agency for Research on Cancer (IARC). A review of human carcinogens: Radiation. Vol 100D (2012).

Darby, S. et al. Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies. BMJ 330, 223 (2005)

Brown, K. F. et al. The fraction of cancer attributable to known risk factors in England, Wales, Scotland, Northern Ireland, and the UK overall in 2015. Br. J. Cancer. 118, 1130-1141 (2018)

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