The British-produced Smokerlyzer can detect minute levels of carbon monoxide. Even a few drags of a shared cigarette are detectable. Unlike teachers and parents, the machine cannot be fooled by sucking mints.
The machines are being used to educate children about the dangers of smoking rather than punish them. At some schools pupils who abstain after the initial test are rewarded with free leisure club passes.
Among those who have taken part are schools in Huddersfield, West Yorkshire, where the device has started to deter some pupils from smoking. Pat Hodgson, of the Huddersfield NHS Trust, has sent nurses into local secondary schools to test pupils. 'When young people think of the health risks, they think of cancer in 50 years time. But if you show them the risks now, they take it on board,' she said.
Forth Valley Health Authority in Scotland plans to introduce the Smokerlyzer to 12 comprehensives after a successful pilot scheme. Pupils at Lornshill Academy in Alloa, Clackmananshire, and at McLaren High School in Callander, Stirlingshire, recently completed a six-month programme of Smokerlyzer tests.