The problem stems from the widespread misuse of nitrous oxide, commonly known as “laughing gas.”
While the gas has industrial and catering uses, for example in food preparation, it has also been widely misused for recreational purposes.
When these pressurised cylinders enter mixed waste streams they can explode or intensify fires in collection vehicles and at processing facilities when crushed or subjected to heat, risking damage to plant and serious injury to workers.
Unintended consequence of laughing gas ban
The sale of smaller canisters was banned in 2023, following the criminalisation of nitrous oxide for recreational use.
As a result, the market shifted towards larger “catering-style” canisters that contained significantly more gas. Small chargers and large half-kilo canisters are sold or acquired, filled into balloons and discarded in parks, streets or household bins.
That means they enter materials recycling facilities, transfer stations and EfW plants that are not designed to manage pressurised gas containers.
Even when “empty,” canisters can retain enough nitrous oxide to rapidly expand under the high temperatures inside an EfW furnace or when mechanically crushed in sorting lines, leading to explosions or intense combustion.
This mirrors wider trends of rising waste fires and explosions linked to problematic waste streams such as lithium-ion batteries and disposable vapes, which have already attracted significant attention for the damage they cause at facilities and in collection vehicles.
‘Huge increase in the number of canisters discarded’
Waste management operators reported that incidents involving N₂O canisters are not isolated.
At Suez’s EfW facilities, Managing Director for Suez’s Energy Division, Tim Otley has described a “surge” in nitrous oxide canisters arriving in the residual waste stream, escalating into a serious safety concern for energy recovery facilities (ERFs).
For instance, at Notting Hill Carnival, Suez collected 13 tonnes (around 12,000 units) of canisters.
Otley commented: “The massive influx of larger high-pressure cylinders poses a severe explosion risk; even supposedly empty cannisters can retain residual product that rapidly expands upon heating.”
“As well as the human cost of Nitrous Oxide abuse, there are real community impacts, with some larger facilities now averaging 5 to 10 explosions per day.”
Veolia similarly reported numerous minor incidents at least 28 significant explosions at EfW facilities this year linked directly to canisters.
Donald Macphail, Chief Operating Officer at Veolia UK, added: “We have seen a huge increase in the number of canisters discarded, both in our collection vehicles and treatment facilities.
“Canisters discarded improperly in bins are a sector-wide problem, as they frequently cause explosions that can put frontline workers at risk and damage recyclable materials.”
Deposit return scheme for gas canisters
In response to the threat, waste companies are taking a range of steps to manage N₂O canisters more safely where possible and to reduce the incidence of dangerous material entering waste streams.
Veolia launched what it described as the UK’s first processing line designed to safely treat nitrous oxide canisters at its Empire facility in Birmingham in 2024.
This line captures and discharges the gas in a controlled manner by separating the nitrogen and oxygen components before recycling the empty canisters, reducing the risk they pose during waste treatment.
However, the scale of the problem means that waste companies cannot tackle the issue alone.
Suez has called on the Government to:
- Restrict sales: Tighter regulation on the sale of large-format canisters, ensuring they are limited to verified professional and industrial users
- Deposit return schemes: Introduce a mandatory deposit return scheme (DRS) for all pressurised gas cylinders, creating a financial incentive for safe return
- Mandatory waste tracking: Implement digital tracking for high-capacity canisters to identify sellers and hold producers accountable for the lifecycle of their products
Otley added: “A single incident could result in costs being incurred of hundreds of thousands of pounds due to repairs, unplanned downtime and diverted waste.
“These are impacts that hard-pressed council budgets can ill afford.”
Subscribe for free