Radon tests to be done at 1,150 Highland council houses
About 1,150 council houses in the Highlands are to be tested for radon gas.
Highland Council said the monitoring will be done in the areas where there was the highest risk of the naturally occurring radioactive gas.
The local authority said it was writing to tenants in parts of the Badenoch and Strathspey, Wester Ross and Strathpeffer and Lochalsh wards.
Also, Caol and Mallaig and Landward Caithness.
Tenants in East Sutherland and Edderton, Dingwall and Seaforth and Aird and Loch Ness will also receive letters about the tests.
Highland Council said there was no need for any immediate concern, and there was no acute risk from radon.
Last month, Historic Scotland said the visitor centre at Urquhart Castle on the shores of Loch Ness would be monitored for radon gas.
It said the detectors were being installed as a precaution and in response to the results of tests in nearby Drumnadrochit.
High levels of radon gas were detected at the village's Glen Urquhart High School and primary in February.
The levels have since fallen and Highland Council said measures were being taken to reduce them further.
Historic Scotland, which owns the visitor centre and the ruins of Urquhart Castle, said the visitor centre was in a low risk area for radon.
Tests will not be done in the castle ruins because the gas only poses a risk in confined spaces. The monitoring will last three months.