In a new scheme by North Yorkshire police, nine devices were trialled at venues on the weekend of 9 January and a further six will be trialled this weekend.
The breathalysers have been given to door staff to prevent people who have had too much to drink from getting into bars and pubs.
Police maintain not everyone will be breathalysed, just those who are suspected of being too drunk. Door staff will still use their judgement on an individual’s level of intoxication and whether they can enter the premises.
According to North Yorkshire police, an alcohol reading of twice the drink drive limit or higher could “greatly increase the chances of someone being refused entry”.
'Tackling drink-related violence'
Acting inspector Andy Godfrey of York Safer Neighbourhood Team, said: "The breathalysers are another tool to help us tackle drink-related disorder and violence.
"Much of the disorder and violence we are called to deal with is triggered by excessive alcohol intake. Being drunk and out of control also makes people more vulnerable. The breathalysers will support door staff in the difficult job of challenging people who they believe have drunk too much.”
He added: "So far, the devices have been well received by local licensees and we hope they will have a positive impact on York's thriving nightlife."