ITV News reporter Katharine Walker has been investigating the rise in underage vaping in schools.
Headteachers are concerned that more and more children are struggling to concentrate in class because they are addicted to vaping.
The majority of vapes on the market contain nicotine, which is shown to negatively impact developing brains.
But underage vaping is on the rise and schools are having to create new policies to crack down on the issue.
Selling vapes to under 18s in the UK is illegal but research shows the number of 11 to 17-year-olds vaping has doubled in the last two years.
The survey from Action on Smoking and Health (ASH) found 7% of 11 to 17-year-olds vaped on a regular basis in 2022, up from 3.3% in 2021.
Nearly half of those who vaped (46.5%) said they'd bought the vapes themselves from shops.
Vice principal Mark Newstead says it's "a real issue"
E-cigarettes come in all shapes and sizes, but many are smaller than a USB drive and can be easily hidden at schools.
Vice principal Mark Newstead, of Garforth Academy in Leeds, says it's becoming increasingly difficult to police as some of them "look like highlighters."
He said: "From speaking to colleagues nationally it is a real issue. With nicotine addiction we see things things like mood swings and students unable to concentrate during lessons."
The popularity of underage vaping is also a cause for concern among teenagers themselves.
After a survey found some teenagers were stealing vapes from bins, year 11 students at Garforth Academy built a website to educate other pupils about the effects of vaping.
With the help of charity NextGenLeaders, they also installed posters and amnesty boxes around the school and local community.
Joshua Cheetham, a student at Garforth Academy, said: "We realised that if people are so desperate to vape that they're stealing them from bins or gutters, they must be highly addicted and it must be solved because it’s a big issue.”
Fellow Garforth Academy student Olivia Hall added: "Something needs to be done. A lot of people from even year six know vaping is happening and they’re going to fall into it, because it’s peer pressure. It’s a trendy thing, all the popular kids do it.”
With teachers spending more money and time trying to police underage vaping, they want to see tighter regulations.
Is vaping safe?
GP Semiya Aziz is also keen to see more public awareness about the impact of vaping and nicotine on young people.
Recent studies have shown that teenagers are more vulnerable to nicotine dependency than adults.
It's also thought that chronic nicotine exposure in young people can impact brain development, leading to attention deficit conditions and mood disorders.
Dr Aziz said: "Normally a young brain will develop and mature up until the age of 25. But in young people that nicotine interrupts those brain connections, affecting memory, affecting mood, affecting impulses. It is extremely harmful because it results in an addictive type behaviour."
In a statement, the Department of Health and Social Care said it has "launched a call for evidence on youth vaping to identify opportunities to reduce the number of children accessing and using vape products."
It added: "We are also establishing a new illicit vapes enforcement squad to tackle underage vape sales as well as the illicit products young people have access to."
John Dunne, Director General, UK Vaping Industry Association said: “As we know it’s illegal for anyone under the age of 18 to buy vapes but there’s very little punitive action taken against those retailers that flout the law. What we’re seeing is inappropriate locations selling these products, like sweet shops, barber shops, and that’s really inappropriate we feel.”
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