More must be done to raise awareness of the dangerous effects of laughing gas, councils have warned.
The Local Government Association (LGA) said it was "deeply disturbed" that nitrous oxide - which can result in a loss of blood pressure, fainting and even heart attacks - is still viewed as a safe legal high.
On a single Saturday night, one London council confiscated more than 1,200 canisters of laughing gas, while other local authorities are seizing "hauls" of the chemical, according to the Local Government Association.
Hackney Council in east London said that it took the small metal containers outside the pubs and clubs in Shoreditch on a Saturday night last month.
Officials in Norfolk, Hertfordshire and Thames Valley have reported increasing numbers of cannisters being found.
Some of the key players have praised her landmark speech - but critics say it is too light on detail and time is running out to sign a deal.
A comparatively quiet reception greeted the launch of the new iPhone 8 and 8 Plus - a far cry from the crowds of years gone by.
Footage shows the dangerous rescue effort after the family were left at the mercy of the sea on a boat overturned by Hurricane Maria.