Danish police introduce roadside nitrous oxide breath tests

Danish police have begun using roadside breathalysers to detect drivers under the influence of nitrous oxide, commonly known as laughing gas, DR reports.

The device, dubbed the “gasometer” by officers, screens for nitrous oxide in exhaled breath, measuring levels in parts per million. A positive result prompts a blood test, as breath readings alone cannot be used as evidence in court.

Two police districts near Copenhagen are piloting the technology as part of a research project involving the University of Aarhus. The initiative aims to clarify how long nitrous oxide remains detectable in the body and is funded by the Victim Fund.

Traffic cases involving nitrous oxide have surged, with national police data showing a tenfold increase in six years—from 57 reports in 2019 to 866 in 2025. Recent fatal crashes have been linked to drivers inhaling the gas before getting behind the wheel.

Nitrous oxide use while driving was outlawed in November, even without an accident occurring. Police previously relied on visual cues, such as empty gas canisters, to justify blood tests.

Steen Harpsøe, a police inspector with Copenhagen West Police, said the breathalysers will help identify more offenders while reducing unnecessary blood tests. He noted a common misconception that nitrous oxide leaves the body immediately, when in fact it can be detected in blood for hours after use.