Radon is a colourless and odourless gas

The scheme in the Kerrier area to identify "at risk" properties is being run by the Department for Environment, Food and Rural Affairs (Defra), the National Radiological Protection Board (NRPB) and the Buildings Research Establishment.

Radon is a colourless and odourless gas which exists naturally across the UK, but is found in much heavier concentrations in Cornwall. In high concentrations and with long exposure it can be a cause of lung cancer.

The free test is available to any household which applies for one before 31 January.

Remedial work

About 8,300 homeowners have accepted the offer of the free test, and more letters have been sent to people living in high radon areas who have not yet responded to see if they want to have the check.

Any homeowner can apply for an easy-to-use kit. It has two detectors which remain in the property for three months.

They are sent back to the NRPB and assessed and the result will identify what remedial work needs to be done to the property, if at all.

Kerrier District Council says much of the work is not expensive and it is better for householders to protect themselves from the gas if there are high concentrations of it.