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.
Radon is formed when atoms of uranium-238 decay (see decay series notes).
Radon will also decay, and, if it is inhaled the alpha particles it will emit can damage the internal lung surfaces. Therefore the main health concern is an increased lung cancer risk from breathing in the gas.
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. But out well insulated homes cause a build up of the gas.
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.