NSW RBT breathalysers can be triggered by perfume

Perfume, toothpaste and even hand sanitiser can lead to a positive breath test.

Innocent motorists are being unfairly branded as drink drivers by roadside breathalysing technology that is now so sophisticated it can detect alcohol even when a driver is sober.

Hand sanitiser, perfume, aftershave, chewing gum, toothpaste, mouthwash and menthol cigarettes can all set off the handheld breathalysers used by police.

Motorists pulled over for an RBT are first asked to count to five or 10 in what is called a presumptive, or screening, test.

NSW Police altered their system of roadside breath testing in 2008 to allow more drivers to be tested. Motorists pulled over for an RBT are first asked to count to five or 10 in what is called a presumptive, or screening, test.

The breathalyser will detect any alcohol near the unit. After a positive test drivers are asked to blow into a tube connected to the same unit, known as a three decimal place test. 

Drivers who have not been drinking but give a positive initial test, as a result of alcohol fumes on their bodies or in their car, will not test positive during this second phase and will be free to leave the RBT stop.

However, if this second test results in a blood-alcohol level above .05 for unrestricted drivers, motorists are arrested and taken to a police station, where they undergo a third evidentiary test. These readings are then used in any criminal prosecutions.

So will bathing yourself in hand sanitiser, which can be 60 per cent ethanol, help you avoid a drink driving charge?

The three decimal place and evidentiary test pick up the alcohol on your breath from your lungs, which comes from the bloodstream

Definitely not, says NSW Police Highway and Traffic boss Assistant Commissioner John Hartley.

The three decimal place and evidentiary test pick up the alcohol on your breath from your lungs, which comes from the bloodstream.

"There is no fooling the system. In 80 million tests I have never heard of this happening," Mr Hartley said.

"If someone else is drinking in the car, it's windy or other factors are suspected of interacting with the test, an officer would use a tube on the device. If officers immediately detect alcohol they will use a tube," Mr Hartley said.

He said police streamlined the system because it allowed them to breath test more drivers in less time and reduced the environmental and financial cost from using the plastic tubes for the three decimal place test. Police once used more than 2.5 million plastic tubes, but this has been reduced to 80,000.

Breathalyser unit salesman Greg Staples said having drunk passengers in a car could also set off the screening test as modern breathalysers have sensitive fuel cell sensors that detect even minute traces of alcohol.