The canisters are discarded after people use nitrous oxide, also known as laughing gas, as a means to get high, with the gas causing a happy and lightheaded feeling.
As nitrous oxide-filled canisters are most often used to create whipped cream, they are legal to own, but selling them as a means to get high could leave a dealer facing a seven-year prison sentence and/or an unlimited fine.
This is because the substance comes with a very serious health risk, as last month saw a 15-year-old boy from Dublin become the latest death – one of more than a dozen over the last decade – caused by laughing gas.
With empty nitrous oxide canisters a regular sight across the city, now both the police and the council have increased patrols to clamp down on their use – with police confirming that the substance is being linked to anti-social behaviour.
But residents still feel the issue is not being properly addressed.
Baffins resident Peter James agreed the use of the drug had fuelled an increase in anti-social behaviour ranging from shrieking late at night to the vandalism of playground equipment over the last six months.
He said: ‘Probably the worst affected area is Milton Common.
‘About a week and a half ago, I saw about 200 canisters there.’
In addition to Milton Common, residents report large numbers of canisters regularly discarded around the Mountbatten Centre, Southsea Common, and in car parks along Eastern Road.
Another Baffins resident, who asked not to be named, said the number of canisters in the area was becoming ‘ridiculous’.
He said: ‘They are all over the bus stops.
‘You can have 20 or 30 around a bench.
‘A lot of people feel what's the point of engaging with the council or the police because they just ignore it.
‘It feels like we're beating our heads against a brick wall.
‘The police know it’s going on, and the kids know they can get away with it.’
Only this week a dispersal order was put in place in Buckland. Police said it was largely imposed due to teenage nuisance, which had included dangerous motorbike and scooter riding, fighting, and drug use, including nitrous oxide.
Both the council and the police have said they are increasingly focusing on the issue and the anti-social behaviour it can cause, according to councillor Lee Hunt from Portsmouth City Council.
Cllr Lee Hunt said: ‘We know it is a city wide issue - we are certainly cleaning up a lot of these canisters.
‘We are very concerned about it and our patrols are coming across its use frequently.
‘We have been dedicating our warden patrols to talking to the kids using it.
‘And parents need to sit their kids down and explain the dangers of doing it. They need to be in charge of themselves.’
Resident reports were helping the police to co-ordinate their patrols to tackle the issue, according to Southsea Neighbourhood Inspector Marcus Cator.
He said: ‘We are aware of issues around the use of nitrous oxide canisters being used in certain areas of the city and reports from residents where this has been linked to anti-social behaviour are helping us to develop our ongoing patrol plans.
‘In response to these reports we have increased our patrols in these priority areas.’
But alongside patrols there is a need for harm reduction messages, according to Darren Carter who is team leader at the Recovery Hub, a drug support group, in Elm Grove, Southsea.
Darren said: ‘It’s a relatively safe drug with little links to mortality compared to other drugs.
‘Putting more patrols on the streets with the objective of dispelling the drug use is likely to simply move it out of sight, and won’t change its use.
‘This is generally what happens when there are crackdowns on substances - the use doesn’t stop, it just becomes less visible.
‘What is really important is to stress harm reduction.’
Taking a normal breath when inhaling from a balloon filled with the gas can ensure users maintain a steady flow of oxygen to the brain, according to advice from national drug support charity FRANK.
Inhaling directly from the canister can cause frostbite – as the gas inside is often -40C – and faulty canisters have been known to explode.
Residents fear groups using nitrous oxide will continue to move across the city to avoid patrols.
Peter said: ‘Patrols just move them around - it becomes a bit of a game.
‘People need to stop using it altogether.’