Small silver canisters littered on streets, near parks and across communities have become a common sight in Wales.
Inside those canisters is nitrous oxide.
The chemical compound is something traditionally used in baking or in hospitals as a pain killer.
But it is also inhaled as a drug, known as laughing gas.
ITV Wales spoke to a number of university students who say nitrous oxide or laughing gas - is easy to get hold of, popular at parties and something they all do.
But they know taking it can have serious consequences.
So what is the law?
In 2016, it became illegal in Wales to sell nitrous oxide for human consumption under the Psychoactive Substances Act.
There’s no penalty for possession, unless you’re in prison.
Supply and production can get you up to 7 years in jail, an unlimited fine or both.
A recent Global Drug Survey listed it as the fourth most used drug in the UK, behind ecstasy, cocaine and cannabis.
The Royal College of Nursing claims nitrous oxide is often seen as being low risk and offering a short, harmless burst of euphoria. But the Office for National Statistics data shows there were 25 deaths directly linked to the gas between 2010 and 2016.
Professionals argue more regulation is needed and more education on the risk of taking laughing gas.
"The biggest risk is they're not getting enough oxygen - and if you have no oxygen it puts excess strain on the lungs and the heart and that - in extreme circumstances, can be fatal", Neil Evans of the Royal College of Nursing said.
He added, "It should be more tightly controlled - there should be a law about how you can sell it, where you can sell it, and who can sell it".
At the moment - nitrous oxide, called noz, whippits and hippy crack - and the tools to inhale it are easy to get hold of.
Trading Standards are working with the police to ensure more shop keepers realise the legal implications of selling it as a legal high.
"We've asked traders to be very aware of what's going on in the community - and to look out for signs for why people would be purchasing this type of product - and of course their intended use", Christina Hill from the Shared Regulatory Services told ITV News.
"I would urge retailers not to sell the balloons and the crackers along with the products which provides the facility for the purchaser to be able to inhale the products".
She said where they find shopkeepers selling it for recreational use, they are seizing the products and launching criminal proceedings against those retailers.
According to the anti-drugs campaign Talk to Frank, the risks of inhaling nitrous oxide include:
Dizziness, which might make you act carelessly or dangerously
Heavy regular use can lead to a deficiency of vitamin B12 and to a form of anaemia
Severe B12 deficiency can lead to serious nerve damage, causing tingling and numbness in the fingers and toes. This can be very painful and make walking difficult
Regular use can stop you forming white blood cells properly
It can be hard to judge the amount to use safely
If you have too much you can end up fainting, having an accident or worse