Possession of the class C drug for unlawful use can lead to a prison sentence of up to two years
Archived version: https://archive.is/newest/https://www.independent.co.uk/news/uk/crime/laughing-gas-breathalyser-nitrous-oxide-police-b2975925.html
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Treating cream foamer as a dangerous drug seems a bit overreaching, but yeah, you should absolutely be sober when driving.