Are breathalysers accurate?


It’s the morning after a big night out and you wake up feeling like an insect has been crawling around the inside of your mouth and someone’s been working with a jackhammer on your head. While a hot shower and some painkillers may help you feel better, your biggest concern is whether you’ll be okay to drive and go to work. Will you risk losing your licence or your job if you’re caught in random alcohol testing?

Luckily, you bought a breathalyser last week. A quick test and your luck just doubled-up – 0.04 BAC, so you’ll be okay to drive and go to work. Or will you? Are breathalysers accurate and should you rely on them when making a potentially major decision such as your ability to drive and work?

Are the breathalysers you can buy for personal use accurate?

A quick check online and you’ll soon find you can pick up a breathalyser from as little as $19. A $29.99 unit even claims to be a “Professional Police Digital Breath Alcohol Tester Breathalyser”. With claims like this, breathalysers must be accurate, mustn’t they?

The simple and perhaps unsurprising answer is no.

There are two main types of breathalysers on the market. One is called a semiconductor breathalyser and the other a fuel cell breathalyser. Both essentially use an electric current to measure alcohol levels. The current is generated by reaction between alcohol exhaled by the user and acetic acid and water.

Semiconductor breathalysers, which are cheaper than the fuel cell breathalysers, are certainly not accurate, particularly over time. Fuel cell breathalysers are more accurate and that’s why you’ll see this type of breathalyser used by the police and workplace alcohol testers. But even these are not 100% accurate and need to be calibrated regularly by trained professionals to ensure their accuracy remains high.

You might be thinking, ‘Hang-on, you said breathalysers aren’t 100% accurate. How is it possible to lose my licence or perhaps my job due to a unit that can’t be relied upon to be 100% accurate?”

Simple, you can’t. Professional organisations only use portable breathalysers as guides and will conduct follow-up testing to ensure the result of the initial breathalyser testing is accurate.

Are you OK to drive and work?

So, back to our friend who’s just blown 0.04% into his personal breathalyser. Is he okay to drive and work? Most good quality, calibrated breathalysers have an accuracy of plus or minus 0.01%, which could mean the actual reading is 0.03 or 0.05. That’s for a good, well-maintained breathalyser. The one you can buy at your local shop might not be as accurate. That 0.04% reading may mean you well over the legal limit.

Are breathalysers accurate? Would we risk our licences or jobs on the accuracy of a breathalyser? No way!

Breathalysers used by police forces and workplace alcohol testers may be reasonably accurate, but how accurate are breathalysers you can buy for personal use?

By Michael

Michael is the founder of Integrity Sampling and is responsible for overseeing all national operations. He is based at Integrity Sampling's head office in Melbourne and is also responsible for the co-ordination of drug and alcohol testing within Victoria, assisting in the implementation of drug and alcohol (fit for work) policies and the presentation of drug and alcohol education and awareness programs. You can connect with Michael Wheeldon on LinkedIn

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