Radon gas is a natural radioactive source that everyone is exposed to. It is usually derived from the radioactive decay of uranium in the soil. In the UK about half of the radiation dose one receives comes from radon gas. The amount you are exposed to depends upon the structure of the rocks in your locality. (See Radioactive Rocks) People who live in Cornwall, Northamptonshire, Derbyshire and Scotland have higher than average concentrations of radon in their homes because of the type of rocks their homes are built on.

• The NRPB provides a lot of information, including access to detailed information of radon distribution in the UK.
• An excellent site covering Ireland is at http://www.rpii.ie/radon/maps/map.htm

• The Cornwall Radon Gas Centre gives lots of information and advice to people living in a high-risk area.

The radon concentration in the average UK home is about 20 becquerels per cubic metre. If the concentration is found to be as high 200 becquerels per cubic metre the Department of Health recommends that action is taken to lower the concentration by venting the gas into the atmosphere. When homes were not centrally heated and draught-proofed this would not have been necessary, especially with the big open chimneys.

Companies have developed equipment to measure and monitor radon levels. Local councils and environmental agencies are concerned about the levels of radon in a locality and raise awareness of local people to the problems involved.
 

We became aware of the dangers posed by radon gas after World War Two when large uranium mines were opened around the world to feed the nuclear industry. Miners became exposed to high levels of radon and suffered increased rates of lung cancer. This was due to mutations in their DNA from ionising radiation damage.