Baxter Academy installed sensors to spot when pupils were puffing on vapes and then confiscated the nicotine machines.
However, when they were tested they found many were illegal and potentially dangerous.
The BBC picked up on the school's initiative and headed to the school with a film crew to find out more and actioned the testing of the confiscated vapes.
Principal Matthew Carpenter is concerned about the increasing use of vapes by children.
He said: “The increase in vaping among school children is a national issue and something we were so concerned about that we had vape detectors fitted in the student toilets in a bid to crack down on their use and raise awareness.
“This was picked up by the BBC and, having come to school to learn about our campaign, they tested some of the confiscated vapes, with extremely worrying results.
“Vapes maybe currently considered a safer alternative to smoking cigarettes, but children should not be encouraged to take up vaping as a lifestyle choice, through attractive packaging and social media."
He added: “These may have sweet and fruit flavours but they are potentially dangerous. These test results show illegal vapes are available and are being sold to our children. I don’t wish my students to risk long term harm to their bodies and brains.
“We hope the BBC’s expose will have a positive impact in highlighting the risks and that the authorities will take more stringent steps to stop illegal vapes being so widely available and to stop the sale to under 18s.”
Some of the vapes were even designed to look like highlighter pens which made them even more difficult to spot by eagle-eyed teachers.
In vapes designed to look like highlighter pens, tests revealed they contained 2.4 times the safe exposure level of lead, 9.6 times the safe level of nickel and 6.6 times the safe level of chromium.
BCC heath editor Hugh Pym, who visited Baxter College to talk to students and principal Matthew Carpenter, said: “The testing team said they were the worst set of results they had ever seen."
Research suggests vaping among 11 to 17-year-olds has increased from 7.7 per cent last year to 11.6 per cent and although it is illegal to sell vapes to under 18s, children are being sold to them by some local retailers and dealers.