Radiation monitoring has begun along beaches on the Scottish side of the Solway Firth.
The Solway Firth tests come after particles were found in Cumbria
It follows the discovery of radioactive particles from the Sellafield nuclear plant on beaches in North Cumbria.
Agencies north of the border are collaborating on the survey to see if any has spread to Scotland.
The Scottish Environment Protection Agency (Sepa) was alerted by its English counterpart about an increase in radioactive particles in Cumbria.
A total of 230 contaminated items have been identified there so far - mainly tiny particles of sand or stone.
Now Sepa has commissioned a programme of monitoring beaches on the Scottish coast to see if any Sellafield contamination has spread.
Work started on the beach at Goatwell Bay, near Kirkcudbright.
A specialist vehicle which has been used to monitor beaches near the Dounreay plant in Caithness has been brought in for the task
Sepa has identified sites at Powfoot, Southerness and Kirkcudbright where the tests will be carried out.
The work was due to start in August but was delayed because of a dispute over who should meet the £100,000 costs which has now been resolved.
The tests are in addition to regular checks already carried out around the Chapelcross nuclear plant in Annan.