'Blow Me First' are a company that breath test patrons in night clubs of Melbourne before they decide to drive home. Dave Gould (L in yellow) and Noah Tyler test Jess Culpitt 18yrs old 0447299701 (in white top) and Ciara Henderson 24yrs old 0431063906 (R) at Tramp on King Street.

Dave Gould (left) and Noah Tyler breath-test Jess Culpitt, 18, and Ciara Henderson, 24. Photo: Paul Jeffers

It is 4.15am at King Street club Tramp and 28-year-old Joe is about to discover what it means to drink four full-strength beers, three double shots of spiced rum, three gin and tonics and a shot of tequila.

At least, those are the ones he can remember. He says ''there could have been more''.

He leans in and blows into a breathalyser machine, which soon beeps in with a number. The reading is 0.134, almost three times the legal limit for driving. ''Based on the amount of drinks you've had it's going to be at least 12 hours until you've lost all the alcohol in your system,'' warns breathalyser operator Dave Gould.

In a first-time trial this year, a group of Melbourne clubs are allowing a private business to breathalyse their patrons.

Partygoers are charged $2 a pop by the team from the company, which goes by the name ''Blow me first''. Each Sunday morning an average of 250 people are tested at eight different clubs in the Melbourne CBD and South Yarra. The service has been operating as a trial since September.

Proponents say the initiative helps partygoers understand their limits at a time when many young people drink to the point where they lose count. But there are some concerns the service could give people false confidence to drink and drive or create an unhealthy competition, where friends compete for the highest reading.

At the weekend The Age spoke to one woman who admitted she took the test to see if she had beaten her previous record, which was 0.2 (four times the legal driving limit).

Victorian Alcohol and Drug Association executive officer Sam Biondo said he had reservations about the breath-testing business.

''It might sound attractive, because it may assist some people to know how drunk they are getting, but are the devices accurate? Will it lead to competition among drunks about who can get the highest score?''

Noah Tyler, co-owner of Blow me first, said while they encountered some people who treated the test as a contest, most were alarmed or surprised when they were shown their high readings. He said the highest reading he had seen was about 0.2.

''Whenever they're breath-tested it makes them second-guess buying another drink,'' he said.

''We've worked at festivals where we can actually see first hand the difference we were making. We would literally stand at the gate and breath-test and probably one of the 10 drivers would have been over the limit.''

Tramp bar owner Steve Pethybridge has been allowing ''Blow me first'' staff to test his patrons for the past three months. It is part of a suite of measures he has introduced to help prevent alcohol-fuelled problems. ''It's beneficial for me because I don't want intoxicated people at my venue: one, because it's not good for my business and two, because by law they are not meant to be there.

''The team will come up to us and tell us if they think someone is on their way and we'll monitor them and will lob them a water straight away.''