A laughing gas "craze" sweeping the UK is being fuelled by internet videos which glamorise use of the chemical, council leaders say.
"Hauls" of canisters are confiscated from UK streets every night, with one London council - Hackney - seizing 1,200 on one Saturday alone.
Officials in Norfolk, Hertfordshire and Thames Valley have also reported increasing numbers of canisters being found.
Council leaders are so concerned they have launched a campaign to highlight the dangers of the chemical.
Thousands of canisters are seized every weekend (pic Rob Brewer/Flickr) In particular, the Local Government Association (LGA) is calling for web giants, such as YouTube, to crack down on internet videos which promote use of laughing gas.
The Association, which represents around 400 councils in England and Wales, said it was "deeply disturbing" that people widely view nitrous oxide as a "safe" legal high.
While inhaling nitrous oxide is not illegal, council officers are able to seize canisters under unauthorised street trading regulations.
The LGA has raised concerns that a number of children inhaling the chemical have emerged on the internet, "glamorising" the drug.
It said that the chemical - which is regularly taken at nightspots, festivals and parties - has been linked to a number of deaths.
Abusing nitrous oxide can lead to oxygen deprivation resulting in loss of blood pressure, fainting and even heart attacks, the LGA said.
The Association estimated that it is used by almost half a million young people across the country.
"It is deeply disturbing that this drug, which can be highly dangerous, is still widely viewed as safe," said Katie Hall, chairwoman of the LGA's Community Wellbeing Board.
"It is imperative that users understand just how harmful it can be. This gas can kill and much more needs to be done to get this message across.
"We are particularly concerned about internet pages and uploaded clips which are effectively 'promoting' this as a harmless drug.
"The web giants must do more to crack down on this, they cannot simply sit on their hands and ignore what is happening on their own sites.
"We are calling on the big internet corporations to step up to the plate and show responsibility by providing health warnings and links to drug awareness charities."
Lightning hits Eggborough Power Station in Yorkshire. Pic: Phil Lowe
A flash flood following heavy rain in Maidstone, Kent
There could be more floods on Sunday
Kim Mawby says the drug has given her a normal life
Jennifer Cozzone, from Roche, says Kadcyla is good value for money
A campaign made breast cancer drug Herceptin more widely available
The friends were on a medical placement in Borneo's Sarawak state
Aidan Brunger's family released a photo showing him at his Borneo hospital
Armed police remove a passenger from the plane. Pic: @MattPeterC
A man is escorted of the Qatar Airways flight by police in Manchester
A passenger's photo shows the suspect held in the back of a car
Passenger Matthew Cox took this picture from the plane
Qatar Airways flight QR23 on the ground at Manchester Airport 
The mayor will lend his support to Mr Cameron's push for EU reform
Alex Salmond (L) will go head-to-head with Alistair Darling
The big vote on Scotland's future is just weeks away
Lord Kitchener warned the Cabinet of a drawn-out bloodbath in Europe
Newspaper sellers in the run-up to war on August 1, 1914
British soldiers in a shallow trench during the Battle of the Somme
The couple were married in 1989