Can you trust personal breathalysers?

CHOICE trialled electronic and disposable breathalysers and the results were disturbing.
 
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01 .Introduction

Breathalyser and empty glass

Nine breathalysers priced from $6 to $199, trialled by CHOICE staff

Given the many perils of drink driving, personal handheld breathalysers that claim to show whether you’re over the legal drinking limit may seem appealing. But can you really rely on them?

Personal breathalysers give an indication of a person’s blood alcohol concentration (BAC), which is only measured accurately in a blood test. More personal breathalysers are now available since CHOICE last trialled them in 2005; you can buy them online, at car repair workshops and even in supermarkets. But greater availability hasn’t improved their accuracy.

In this trial, the inaccuracies were disturbing: seven of the nine breathalysers underestimated blood alcohol levels. This means the readings indicated it was fine for the user to drive, when in fact they were over the legal driving limit.

We found two types of breathalysers readily available — electronic and disposable — and trialled nine models priced below $200. Our trial results are a warning that these devices can provide motorists with a false sense of security.

Please note: this information was current as of September 2009 but is still a useful guide to today's market.


Video: Personal Breathalysers

How much faith should you place in a personal breathalyser unit?

CHOICE Verdict

Based on our results, CHOICE does not believe any of the personal breathalysers we trialled are sufficiently accurate to be recommended for use. Indeed, several of the manufacturers or distributors we contacted said the readings from the devices are to be used only as guides, not as a conclusive measure.

Drink driving is a significant factor in the road toll across most states. According to the NSW Roads and Traffic Authority’s 2007 crash data, 1947 accidents were alcohol-related. Every year about 18% of people killed on NSW roads had consumed alcohol, while alcohol is also implicated in about one-third of the annual fatalities of people aged between 17 and 24. In Victoria last year, 28% of all drivers and motorcyclists killed on the roads had a blood alcohol reading of 0.05 or more.

Given a personal breathalyser provides only estimates — and they can be quite off the mark – why take the risk? If you’re in any doubt at all, just don’t drive when you’ve been drinking.

Models tested

Electronic

  • Alcohawk
  • Alcolimit Enforcer 2
  • Alcosense Mini
  • Andatech AL6000
  • Digitech
  • FiT 208-S
  • Sobermate

 Disposable

  • Breathscan
  • Redline
 
 

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Crucially, many of the devices on trial underestimate blood alcohol concentration blood alcohol concentration (BAC) readings, falsely indicating the user is under the 0.05 limit. In gauging the results, CHOICE looked at how far each device deviated from the evidential machine’s readings (see our testing method).

The disposables are only designed to tell you if you’re under or over 0.05 and both tended to err on the side of caution. Redline recorded no underestimates but overestimated breath readings twice. Of the seven electronic devices, Alcohawk and SoberMate delivered readings closest to the readings registered by the evidential machine, scoring above-average accuracy levels. Both also provided the least number of underestimates.

Overall, the worst performers were the FiT, Digitech and Alcolimit. All three scored poorly for accuracy, with an unacceptable number of underestimates (see the table, below).

Results table

Calibration required

Most of the electronic breathalysers require recalibration for accuracy at least every six months and usually this can be usually done by taking the device to the distributor or manufacturer. Typically, this costs $50 plus postage.

Even though FiT’s user manual says the device should be recalibrated every six months, we couldn’t find information on how to do this or who to contact. In fact, we only managed to contact its manufacturer, A&A Product, through one of its Australian distributors.

FiT’s product manager in Hong Kong told CHOICE the device should have been calibrated in Australia before being sold to consumers. However, when we checked with the online retailer, they were unaware it needed to be calibrated before sale. He added that importers are responsible for calibrating the breathalysers, and if they do not provide the service, users could send it to A&A Product, in Hong Kong, for this to be done.

03.Test method / Voluntary standard

 

Ten trialists — six men and four women of varying ages and weights — took part in our trial. Each reading from the handheld breathalysers was compared with that of a calibrated Dräger Alcotest 7110, an evidential breathalyser used by police for the detection of drink-driving offences in all states except NSW and Queensland. The evidential machine readings were used as the benchmark to assess the accuracy of readings taken from our trial breathalysers.

After abstaining from alcohol for 24 hours, trialists took a reading on the evidential machine to confirm they registered zero BAC. They familiarised themselves with how each breathalyser worked and rated them for ease of use, which included understanding the instructions, preparing the breathalyser for use and reading the results.

After eating lunch, the trialists were allowed to consume between one and three standard drinks (see What’s in a Standard Drink) in one hour, followed by a 20-minute break to dispel mouth alcohol before using the breathalysers.

The trialists then used each breathalyser, including the evidential machine, and recorded their BAC readings. They were asked how confident they felt about driving a car safely and whether they believed they were under the legal limit.

Voluntary Australian standard

Of the devices on trial, the SoberMate, Andatech, Alcolimit and Redline are certified with the voluntary Australian Standard, AS 3547, which specifies a set of minimum performance standards for personal breath alcohol testing devices.

The standard’s test method is to pass vapour containing alcohol through the breathalysers. While the devices performed to Australian Standards, our trial indicates that certification does not reflect their performance in real-life scenarios.

04.Usability of the devices

 
Breathalysers group shot

The tested breathalysers.

The trialists assessed the ease of use of each device according to how easy it was to follow instructions, prepare the device and read the results.

They found most of the electronic breathalysers easy to use. This type is reusable, with many resembling mobile phones. Generally, all that’s required is to press a button on the device, wait until prompted, blow into the mouthpiece for a few seconds and the reading appears.

The FiT 208-S, which claims to be user-friendly, rated lowest for ease of use. Our trialists found its operating instructions “too complex”. Interpreting its readings was also confusing — the BAC levels in the instructions are stated as a range of percentages that require conversion.

Another downside is if your reading is below 0.015, the device only indicates “Lo”. Similarly, trialists found the Digitech’s instruction leaflet hard to understand. This model also delivered too many underestimates (see table). The Alcosense Mini has easy-to-follow instructions and is the only electronic breathalyser that does not require a mouthpiece, but it delivered poor accuracy results.

Disposables hard to use

The two disposable models on trial, BreathScan and Redline, are about half the length of a pen and consist of chemical crystals within a glass tube. The crystals in both react to alcohol fumes and change colour when they’re over 0.05. Our trialists rated both poorly for ease of use, just as they did in 2005.

BreathScan requires you to break the seal and blow hard into the tube for 12 seconds. If you’re over the limit, the crystals change from yellow to a pale bluish-green. But this was not always obvious to our trialists.

The colour change in the Redline from yellow to green was much more obvious than in the BreathScan, however, many trialists still found it hard to interpret the readings. The colour change progresses along the tube and if it stayed on the red line, trialists could not understand what the reading meant. When the colour change crosses the red line, it means the trialist’s BAC is above the 0.05 limit. Conversely, when the colour change stays below the red line, it means the BAC is under 0.05.

The Redline is also cumbersome to prepare. To use it you must break off the ends of the glass tube, attach a plastic bag, blow into it to inflate it, then squeeze the air through the tube to obtain a reading — a feat that would be difficult to manage discreetly in a pub.


05.What's in a standard drink

 
Standard drink

A standard drink is defined as one containing 10 grams of alcohol. It is a way of measuring the quantity of alcohol and is a guide for staying under the 0.05 limit; For men, it is no more than two standard drinks in the first hour, and one standard drink per subsequent hour. Women should drink no more than one standard drink per hour.

Our trialists' readings

The rate of alcohol absorption also varies with gender, age and weight. In our trial, a man and a woman who both consumed three standard drinks had very different readings. The 49-year-old male trialist who weighed 100kg had a reading of 0.01, while the woman, aged 29 and weighing 54kg, had a reading of 0.04, close to the 0.05 legal limit.

When asked how confident they felt about driving safely and if their BAC was under the legal limit, the woman said she was 100% confident about both. The man, on the other hand, despite registering only 0.01, said he was neither confident of handling a car, nor having a BAC below the limit.

BAC limits by state

The legal limits for each licence class vary between states. In Victoria and Queensland, a zero BAC limit applies to learner, provisional, truck, bus and taxi drivers, while all other drivers must stay under 0.05 BAC.

In NSW, three limits apply:

  • zero for all learner and provisional drivers (even if you’re from interstate or overseas)
  • 0.02 for taxi and bus drivers, as well as heavy and dangerous goods drivers
  • 0.05 for all other full licences