You might have seen them spread all over the ground after a Saturday night or a big music festival.
Nitrous oxide canisters - known on the streets as 'nangs' or 'NOS'- have been used as a sedative and pain relief for more than 150 years, but the gas has become a popular recreational drug around the world.
The metal canisters are to be banned in the United Kingdom as part of a wider crackdown on antisocial behaviour.
In New Zealand, the legislation around the supply of the gas for retailers is blurry, but the Drug Foundation said there is no reason for panic.
Recreational use
Nitrous oxide was normally sold in large cylinders to registered dentists and doctors, and it could only be used under their supervision.
However, the gas can be also used as a propellant to make whipped cream and it is sold in dairies and vape shops around the country.
Popular among young adults, users release the contents of a canister into a balloon and inhale it for a short-lived high, causing euphoria and relaxation.
Drug Foundation Executive Director Sarah Helm said although inhalation was not recommended, nitrous oxide misuse would not cause severe harm.
"Unless they are using it incredibly often and frequently, they might experience a B12 deficiency and consequently some issues with their nerves."
In 2021, New Zealand Medical Authority MedSafe sent a high alert about the recreational use of the gas.
"When someone inhales nitrous oxide, they're limiting the amount of oxygen going to their brain. This could lead to the person passing out or dying through suffocation or heart problems.
"The risk of this is likely to be higher if the gas is being inhaled in an enclosed space, or if a lot is used at the same time," it read.
A pack of 20 canisters can be found in dairies, costing from $15 to $20.
RNZ visited a few shops in Auckland central to check how easy it was to access.
In one store, we were asked for our IDs, to state the reason why we were buying the canisters and to fill in a form with contact information.
When asked about the necessity of the form, the retailer said it was to prevent people from buying it illegally.
"It's just so you are aware that it's not used for inhalation purposes. The only way for us legally to sell these products is to ask customers to fill up this form," the retailer said.
However, a few blocks away in a different shop, RNZ asked for whipped cream canisters, and the gas was sold with no questions asked or ID required.
The gas could also be purchased online.
But should the government tighten the retail supply?
Through a statement, MedSafe said it strongly advised against the recreational use of nitrous oxide, saying it could have serious physical effects on the lungs and mouth, could interact with other medicines or drugs, and could lead to other medical issues with prolonged use.
It said it was continuing to review issues around the supply of nitrous oxide.
Group manager Chris James said those who sold the canisters for inhalation could be prosecuted for illegally selling a prescription medicine, subject to the provisions of the Medicine Act 1981.
"Importers, distributors and retailers are responsible for the products they sell under the medicine legislation," James said.
"This is a general warning letter to importers, distributors and retailers of nitrous oxide in New Zealand, any person or business involved in the illegal supply of nitrous oxide may be prosecuted."
Retailers selling the canisters for inhalation could be either jailed for up to six months or fined up to $40,000.
Helm said the gas should not be available in every dairy, but the Drug Foundation was much more focused on reducing harm from other drugs.
"We are not seeing a new trend of nitrous oxide use in New Zealand. There has been a small amount of use over a period of time and it's not the top of the concern list here at all."
The government had much more important things to deal with, Helm said.
"The drugs we need to be concerned about in New Zealand in this point in time is alcohol, methamphetamine, synthetic cannabinoids and opioids in our very dynamic and changeable drug market.
"As a result of the moral panic around it in the UK, I hear that are also now restrictions on women being able to access it for childbirth. Let's be proportional in our considerations here."
More regulation needed
On the streets of central Auckland, people had mixed feelings about the regulation around the retail supply of nitrous oxide.
"At the moment if you are 14 you can buy it, because there's no regulation. It's easy to buy, especially if you don't have an ID. Some dairy owners really don't care as long as they get money for it," 18-year-old Courtney said.
"They should be obviously regulated because they can be used for cream charges, but think there are bigger problems that the government should be focusing on," 18-year-old Sabine said.
"People obviously abuse it, but most people that I know do it occasionally - on a night out they would get a 20 pack [of canisters] and share around. If they try to fully ban them, people would just stock up, it would become a black market," a 25-year-old resident said.
The Ministry of Health said regulating the retail supply of nitrous oxide would be a matter for the police.
However, the police said it was best to contact the Ministry of Health regarding legislation around the gas.
RNZ
