The Scottish government has announced that it is to roll out free tests for homes at risk from a cancer-causing natural gas.
The areas of Scotland that have the highest levels of the radioactive gas radon have been highlighted on a new map and include some parts of the Borders, Aberdeenshire, Highland and Orkney.
The free tests will be carried out by the Health Protection Agency, with homes eligible for testing if they have a 5% chance or more of being above the radon concentration "action level" of 200 becquerels per cubic metre.
Radon is only considered dangerous if it is in high concentrations with long-term exposure, although it does increase the risk of lung cancer.
In Scotland as a whole, about 62,000 homes are located in Radon-affected areas, although it is estimated that only between 1,000 and 3,000 of these will have radon concentrations above the action level.
Health Secretary Nicola Sturgeon commented: "The build-up of radon in houses can put health at serious risk, and is estimated to cause between 100 and 200 lung cancer deaths in Scotland every year.
"This new map identifies the areas of Scotland most affected and the measures announced today by the Scottish government will assist those homeowners most at risk to get their properties tested, so they know whether works might be needed to address the problem."