Laughing gas sold in Leeds through Facebook
Party drug nitrous oxide is being sold illegally across Leeds via Facebook, a BBC investigation has found.
The sale of the gas for human consumption has been illegal since May when the Psychoactive Substances Act came into force.
However, the BBC was able to buy several canisters of the drug, known as laughing gas, after contacting a dealer advertising it for sale on Facebook.
Two men have been arrested as a result of the investigation, police said.
Facebook has said it "is looking into the matter".
According to research, nitrous oxide is now ranked the fourth most popular drug in the UK, excluding alcohol, tobacco and caffeinated energy drinks.
One woman told the BBC: "Every time you go out, if you go to a house party, it's always there.
"It probably should [concern me] but it's just become quite normal."
Another said: "It's a lot harder now to get it at clubs, but definitely at house parties it's everywhere."
- Effects: Feelings of euphoria, relaxation and calmness, dizziness, difficulty in thinking straight and fits of giggles/laughter, sound distortions or even hallucinations
- Risks: If gas is consumed in an enclosed space, or if a plastic bag is used, it may cause lack of oxygen; heavy regular use can lead to severe vitamin B12 deficiency and anaemia; it may also depress formation of white blood cells
- If someone collapses after using nitrous oxide, call an ambulance immediately, turn them on to their side to avoid choking and stay with them until the ambulance arrives
Experts said the use of the drug is potentially fatal.
Dr William Harrop-Griffiths, from the Royal College of Anaesthetists, said: "When you breathe in nitrous oxide it is absorbed really quickly in to the body.
"It goes straight to the brain and it can cause unconsciousness within 30 to 45 seconds.
"The unconscious human being is at risk and if there are not people around to support their airways, support their breathing, you die as a result of unconsciousness."
According to research, there were 17 deaths related to the use of laughing gas in the UK between 2006 and 2012.
Following the BBC investigation, West Yorkshire Police said two men, aged 24 and 20, were arrested on suspicion of possession of nitrous oxide with intent to supply.
They were arrested after officers discovered nearly 5,000 canisters and 7,200 balloons at an address in Gipton, Leeds.
Both men were released on police bail.
According to Facebook's Community Standards the site prohibits "any attempts by private individuals to purchase, sell, or trade prescription drugs, marijuana, firearms or ammunition" and it encourages users to report suspicious activity.
The page used to sell the nitrous oxide has been taken down.
For more on the investigation watch BBC Look North at 13:30 and 18:30 GMT on 19 January.