Facing the sea, between the illuminated luxury boutiques of Cannes, municipal police officers wave their flashlights to stop a car with three young women inside and carry out a nitrous oxide check. âWe are the first in France,â the police officer proudly exclaims.
Since August 22, 2026, the city's mayor, David Lisnard, has made his municipal police force the first in France to equip itself with nitrous oxide detectors. âPending [âŠ] the Ripost lawâ, which will come into force in February 2027, âwhich will make consumption, detention and driving under protoxide a crime, we are choosing anticipation to protectâ, assured the man who is also a candidate in the presidential election, on August 23, in a video published on the city's social networks.
No legal value, only prevention
The principle? We blow, like in a breathalyzer, and the result comes out in a few seconds. âWe had three positive tests in one month, out of around a hundred screenings,â explains Yves Daros, the director of the municipal police, one of the largest in France with 200 police officers for 74,000 inhabitants. âThese are all cases in which we may have avoided serious accidents,â he specifies.
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The Cannes town hall has already issued orders to prohibit the consumption of nitrous oxide on public roads. But the police can only note the offense as a "flagrant offense", when they see a driver with a balloon in his mouth, or when they find canisters of nitrous oxide in the car. The detector is not approved by state services, it has no legal value to qualify any offense. For the moment, it is therefore only used for prevention: âThe law does not allow us today to issue fines in relation to this testâ, recognizes Yves Daros. âBut when we come across a positive driver, as police officers we cannot let him go. We continue our roadside check, we do another test after an hour, and if it becomes negative, he can leave. But at least for an hour he will not have put anyone in danger.â
Other cities soon equipped
The director of the municipal police claims to receive phone calls from town halls all over France, seeking information about the detector. He directs them to Olythe, a start-up based in Aix-en-Provence. Initially specializing in connected breathalyzers, it claims to have developed the first reusable nitrous oxide detector, at a price of 900 euros excluding taxes. âWe are about to equip Bobigny, BĂ©ziers, Puteaux and Coudekerque-Branche, in the North. And others will follow,â assures its founder Guillaume Nesa. The town hall of Bobigny confirms to franceinfo that it has ordered detectors, that of Coudekerque received its copy during the week of September 21.
The entrepreneur does not understand why his detector does not equip the national police: "I think it is a big gap for the police. With the Ripost law, we are going to ask the police to detect drug use behavior by eye. We are showing that solutions exist and that they work." His device nevertheless won the medal from the Ministry of the Interior during the last LĂ©pine competition. Guillaume Nesa would like to make a deal with the national police and the gendarmerie, but assures that he âhas no more contact than thatâ for the moment. The Ministry of the Interior, contacted by franceinfo, is stingy with comments on the issue: âState services are currently testing a device for detecting nitrous oxide, with a view to its approval.â
Scientists express doubts
The authorities' caution may be due to the doubts expressed by several scientists who work on nitrous oxide. âWhat is demonstrated by the scientific community is that nitrous oxide remains detectable for a very short time in exhaled air. When we do not detect it, does that mean that it was not there? Absolutely not, no scientific proof,â explains Guillaume Grzych, biologist at Lille University Hospital, and president of the Protoside network, which warns of the dangers of this gas, very popular with young people.
âAbove all, the device seems to be subject to numerous interferences: a positivity does not necessarily mean that there is nitrous oxide. There are too many unknowns today, and the company does not know how to demonstrate its effectiveness scientifically,â explains the biologist. According to him, even blood tests only detect nitrous oxide 20 to 30 minutes maximum after inhalation.
The biologist estimates that it will take months, perhaps even years, to develop a reliable test. Olythe replies that his detector is already used by the Danish police. Since January, two police districts in the country have been testing the use of the device. âThe sensor result cannot be used to convict a person, it is only a screening tool and any positive result must be verified by a blood test,â explains Charlotte Uggerhoj Andersen, associate professor of forensic medicine at Aarhus University, Denmark. It is finalizing a study with 15 participants to test the reliability of the detector: "No false positive results were recorded by the sensor during our study. It should be noted, however, that the study was carried out in a controlled indoor environment", and not in the context of a police check.
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The Danish police confirm to franceinfo that they have equipped themselves with 30 detectors from the Olythe brand. In eight months, âmore than 30 proceduresâ in which the detector tested positive for a driver were subsequently validated by a blood test. "As the experiment is still ongoing, we are unable to draw conclusions about the effectiveness of the device," explains a police spokeswoman, "but the initial feedback is very positive. So far, a court has convicted three motorists for driving with nitrous oxide in their blood following the use of this screening device. Subsequent blood tests confirmed the presence of nitrous oxide in their blood." The Danes are waiting until they have reached 50 positive tests to assess whether the detector deserves to equip police throughout the country.
