Michelle can barely remember the first time she tried nitrous oxide. After four years inhaling up to five large canisters of the gas every day, her memories are elusive, slipping away almost as quickly as she can recall them.

The memories she does retain are disturbing: brief seizures, driving while high, inhaling the contents of “nangs” – whipped cream chargers filled with nitrous oxide – in public. “It really hooks you because it transforms reality,” the 28-year-old says. “You basically black out for a few seconds.”

Eventually Michelle – whose name has been changed, as have others in this piece – checked into a private rehabilitation clinic on the Sunshine Coast. She remains alarmed by how easy it is to buy the gas. “It’s a quick, cheap high. It’s way too available.”

New figures from the Department of Home Affairs, released under freedom of information, reveal a huge surge in imports of nitrous oxide.

In the first two months of this year, Australia imported more nitrous oxide than it did in all of 2014 and 2015 combined. In 2015, Australia imported 249 tonnes of nitrous oxide. By last year, that had climbed to 3797 tonnes – a more than 15-fold increase. According to CSIRO’s chief climate research scientist Pep Canadell, the volume of nitrous oxide being imported into the country is the equivalent of the annual carbon emissions of about 200,000 cars.

Exactly how much of that gas is destined for recreational use is difficult to determine. Although nitrous oxide, or laughing gas, has legitimate uses in the medical and food and beverage industries, data shows that medical use at public hospitals, for example, has not significantly increased over the past decade.

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