Breathalyser purchasing advice: how to choose the right product

  • What you need to know
  • Alcohol impairs your concentration and balance, prolongs your reaction time, and increases your risk taking.
  • Do not drive under the influence of alcohol. While you can legally drive with low blood alcohol levels, if you go over the limit the penalties are strict.
  • Breathalyzers are a good way to check your blood alcohol levels, but don’t base your decision to drive entirely on them.
  • From simple single-use straw style breathalyzers to multiple-use digital models, there are a lot of different products out on the market.

What is a breathalyzer?

Breathalyzers measure the alcohol percentage of your breath to show how much alcohol is in your blood. They are commonly used by police to check DUI suspects.

man uses breathalyser in car
With a breathalyzer, you can check if you are fit to drive.

Deciding whether to drive

Breathalyzers can help you decide whether to drive after having one drink or in the morning after a heavy night. They will show you your approximate blood alcohol content so you can make a more informed decision about whether you should drive. The basic mantra does however remain true: don’t drink and drive.

How do breathalyzers work?

To use a breathalyzer, all you have to do is blow into it for a few seconds. The results are effectively instant. If you’re using a single-use device, you will see a color change in the tube depending on your alcohol level. Digital breathalyzers show blood alcohol content with a numerical value. These devices can be reused, but you have to replace the mouthpiece with a new sterile one after every use.

To use a breathalyzer properly, you shouldn’t consume anything for at least 20 minutes beforehand – this means no alcohol, cigarettes, or even medication. If you do, you could get a false reading or even de-calibrate your device. To make sure you have an accurate reading that reflects your blood alcohol content, it’s a good idea to do another test five minutes later.

Why is blood alcohol measurable with breath?

Normally, when you breathe, the alveoli in your lungs take oxygen in and excrete carbon dioxide. After drinking alcohol, they will also excrete ethanol from your bloodstream. This ethanol (i.e. alcohol) in your breath can be measured using a breathalyzer. The alcohol level in your breath can then be used to provide an accurate estimate of your blood alcohol content. The alcohol content of your breath is roughly half of your blood alcohol content – if you have a breathalyzer that measures in mg/l then you’ll need to double the value.

Drunk driving

Many people continue to underestimate the dangers of drunk driving. In Europe, one quarter of road crash fatalities involve drunk drivers. In the US, this tragic figure increases to one third – using data from 2019, that’s one death every 52 minutes.

Alcohol makes your reactions slower which can have devastating consequences if you’re on the road. Whether you’re in a car, on a motorbike, or travelling as a pedestrian or cyclist, the risk of a road accident increases even if you’ve only had a small amount. Alcohol impacts your vision and hearing, as well as your ability to concentrate. Accurately measuring distances and speeds becomes much more difficult. Alcohol makes you less able to recognize dangers, and it also makes you more likely to take risks – not a good combination for road safety.

Different types of breathalyzer

There are two main types of breathalyzer on the market: simple single-use devices which use a chemical reaction to give a rough indication of alcohol level, and electronic devices which show a numerical value on a display.

Single-use breathalyzers

Single-use chemical breathalyzers have been on the market since 1953. They generally come either with or without a balloon. Breathalyzers with balloons need to be fully inflated to give an accurate reading. Those without can sometimes be more difficult to use as you don’t know exactly how much you need to blow into them.

alcohol test in bag form
Breathalyzers also come in bag form.

These simple breathalyzers work by chemically reacting to any ethanol in your breath. Depending on how much alcohol you have in your blood, the chemicals in the tube will change color. The stronger the color change, the more alcohol you have in your system. The main advantage of these breathalyzers is that they are inexpensive. However, they are only single use, don’t provide a particularly accurate reading, and have a use-by date.

Electronic multiple-use breathalyzers

Electronic breathalyzers are commonly used by police at traffic stops. The models they use tend to be much more accurate than cheaper home use devices. If you do want a super accurate professional breathalyzer, you can buy one, but it will be expensive. In general, standard home electronic breathalyzers have a 5% accuracy margin. This is good enough for most cases – the best devices have a margin of 0.05%.

Man uses breathalyser
You should use the breathalyzer before you get behind the wheel.

Measuring techniques

Single-use breathalyzers all work using a chemical reaction to give their blood alcohol reading. By contrast, electronic breathalyzers employ a range of different technologies. Depending on the model, they can have either fuel cell, semiconductor, or infrared sensors.

Models with fuel cell electrochemical sensors are the most common type available on the market. They work using electrodes which react with ethanol, producing an electric charge. Alcohol concentration is calculated using the voltage generated by the electrodes.

Breathalyzers with semiconductors work by oxidizing any alcohol present in your breath with a tin oxide compound. The device will then measure the increase in electric conduction on the tin oxide layer to determine alcohol level. Semiconductor breathalyzers are not as stable as fuel cell breathalyzers but are generally cheaper.

Infrared breathalyzers measure alcohol level using light. They are extremely precise and are typically used by police.

Electronic breathalyzer advantages and disadvantages

To use an electronic breathalyzer, you have to blow into a mouthpiece on the device. For accuracy and hygiene, these mouthpieces can only be used once and need to be replaced after every use (the breathalyzer itself can be used over and over again). The only thing preventing continuous use is that you will need to send the breathalyzer for calibration every six months or so.

Apart from being reusable, the main advantage of electronic breathalyzers is that they are much more accurate than their single-use cousins. Being able to read a numerical value on a display rather than judging color change is a big strong point.

Electronic breathalyzers are of course more expensive than single-use ones. You will also need to pay for batteries/electricity, as well as when you send your breathalyzer for calibration.

The values you get on a breathalyzer display are not admissible in court. In the event of criminal proceedings, law enforcement will use blood tests to show alcohol levels as they are legally reliable.

Stationary breathalyzers and ignition interlock devices

There are also stationary breathalyzers on the market, but these are generally much less common than mobile ones. Stationary devices tend to be more accurate because they often use a combination of fuel cell and infrared sensors. These devices are more expensive and not really suitable for home use, so our product selection only covers mobile breathalyzers.

Ignition interlock devices are breathalyzers that are permanently installed in vehicles. To start the vehicle, the driver needs to breathe into the device to make sure their blood alcohol level is not too high. This system is designed to stop drink driving, and is often found in buses, lorries, or in vehicles belonging to people with previous DUI offences. These devices cost around $1,000 to fit.

Image 1: © Andrey Popov / | Image 2: © Jérôme Rommé / | Image 3: © Andrey Popov /