Some things to bear in mind when using your breathalyzer.  

Whilst the Home Office Approved fuel cell devices are pretty much bomb-proof (the saying ‘you get what you pay for’ CERTAINLY applies in this sector)  the personal use semi-conductor devices (i.e. anything that retails for about £100 or less) are made of highly sensitive silicon oxide sensors, which can give erratic readings if affected by any of the following:

  • Extremes of temperature – when the manufacturers’ give their quoted accuracy, it is ‘under laboratory conditions’ (not normally represented in day-to-day life) and at a temperature range of ‘between 20-25 degrees celcius’ (so if it has been sat in your car all night, chances are it WASN’T at that temperature range… especially not in the UK!)
  • How little it is used – in much the same manner as a classic car, a breathalyzer that has been sat doing nothing in a drawer for months is NOT going to function as well as one that is used on say, a weekly basis.  The sensors themselves are prone to ‘drying out’ which can be the cause of unreliable results.  You wouldn’t leave your classic car in a garage for a year, and expect it to run perfectly for its MOT.  Same goes for a semi-conductor.
  • …but also how OFTEN it is used – likewise, if you have the social life of a student and need to used it EVERY night (with high readings!)  chances are, after about 3 months it will certainly need checking and probably re-calibrating.
  • Your health – do you smoke?  Leave at least 15 minutes after your last cigarette before testing.  Are you diabetic?  You could be producing ketones if its a while since your last meal.  It’s unlikely that your semi-conductor device is accurate enough to determine the difference between alcohol imbibed, and alcohol produced and although generally the amounts produced are minimal, added to existing ‘real’ alcohol you would probably need a blood test to determine the levels.  Best leave it till you know you’ve not had anything to drink for 24hrs.
  • That old favourite, the mouthwash – with alcohol included in the ingredients, common sense would hopefully dictate that a test within 15 minutes of using mouthwash is highly likely to give a false positive result.  Not normally something to worry about at the end of the evening, but certainly something to bear in mind ‘morning after the night before’.

With regular use, you will quickly become aware of what your levels are after what amounts, and more importantly, how long it takes you for you to get back down to zero.  If you start to notice erroneous readings occurring which make no sense, in all likelihood it’s time to get it checked and calibrated.  

We can calibrate most of devices out there – contact us via the website and we’ll do our best!



  1. Nick Robin 27th January 2010 Reply

    If you need to recalibrate a test meter, how long would that take, and is it an expensive operation?

    • suzannah 27th January 2010 Reply

      Hi Nick – depending on what type of unit you have, we offer both semi-conductor and fuel cell calibration. The calibration process itself is usually turned around in about 5 working days from receipt of unit, and can be ordered online from our website ( – if in doubt, give our sales team a call and we’ll work out what it is you need!
      Calibration is certainly cheaper than buying a new unit, provided the sensor has not failed – if you let us have a look, we’ll let you know.

  2. Pete Lancaster 30th January 2010 Reply

    This is really good advice and I hadn’t considered the points you make, such as mouthwash. Are there any ‘old wives tales’ we should be wary of that reputedly influence the results?

    • suzannah 4th February 2010 Reply

      Funny you should mention it! New blog post above…

  3. UGG Boots 10th February 2010 Reply

    I found this article useful in a paper I am writing at university. Hopefully, I get an A+ now!


    Bernice Franklin

    UGG Boots

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