A supermarket has fitted blue lights in its customer toilets to combat drug-taking.
The blue light makes is difficult to see a vein
Sainsbury's has installed the lights at its Huntingdon store.
The blue light prevents veins from showing up on arms and are being used deter drug-injecting users.
The lights are common in nightclubs, bars, service stations and a small number of other stores.
A spokesman for Sainsbury's said: "The local council made us aware of a potential drug problem in the area, and, as a responsible retailer, we have introduced blue lighting as a precautionary measure."
A Cambridgeshire Police spokesman said Huntingdon had a known drugs problem and was being targeted with a special operation to reduce drug taking.
"Any initiative which helps our fight against drug-taking is to be welcomed," said the spokesman.
"Although Sainsbury's is not known as a place for drug users, the town does have a problem with heroin and other hard drugs like crack cocaine.
Solved the problem
"There are dealers who are dealing £3,000 worth of class A drugs each day."
The blue lights have also been fitted in the town's Woolworth's store, where they have deterred drug users.
A spokesman for the store added: "Historically there has been a problem with drug users using several retailers' toilets in the town. The blue lights have completely solved the problem.
"It was a decision taken at local level at the store where a problem was identified."