The city of Cannes became the first in France to provide its municipal police with nitrous oxide detectors in August. These devices are designed to detect the presence of nitrous oxide, a substance commonly used as a recreational drug and sometimes in aerosol products. While Cannes has taken the lead, other cities are expected to follow suit. However, the device is not yet officially approved by national authorities, and scientists have raised concerns about its reliability due to a lack of comprehensive studies. Municipal police in Cannes used the detectors to stop a car with three young women inside and conducted a nitrous oxide test. The mayor of Cannes, David Lisnard, who is also a presidential candidate, stated that the city is preparing for the upcoming "Ripost" law, which will make the use, possession, and driving under the influence of nitrous oxide a legal offense. The detectors are not legally recognized and can only be used for preventive purposes. The municipal police director, Yves Daros, mentioned that they have conducted over 100 tests, with three positive results in a month, potentially preventing serious accidents. The city has issued decrees to prohibit the use of nitrous oxide in public, but police can only enforce this in situations where the violation is caught in the act. The detectors are not yet homologated by the state and cannot be used to issue fines. Other cities, including Bobigny, Béziers, Puteaux, and Coudekerque-Branche, are expected to be equipped with the detectors soon. The device was developed by Olythe, a startup based in Aix-en-Provence, which claims to have created the first reusable nitrous oxide detector. The device has won a medal from the Ministry of the Interior but has not yet been adopted by national police or gendarmerie. The Ministry of the Interior stated that they are currently experimenting with a detection device for nitrous oxide in preparation for its homologation. Scientists, including biologist Guillaume Grzych, have expressed doubts about the device's reliability, noting that nitrous oxide is detectable in exhaled air for a very short time and that the device may be prone to interference. The device has been tested by the Danish police, who have equipped 30 units with the detectors. The Danish police confirmed that over 30 procedures have been validated with positive results from the detector, followed by blood tests. However, the Danish police are still evaluating the device's effectiveness and have not yet reached a conclusion.