El Reg tests portable breathalyzers: Getting drunk so you don't have to

Putting booze probes through their paces (all for science, of course)

Sober conclusions

Half of the testing team had to leave following the second round of tests, as they had families to go home to. The remaining participants administered one final beer or wine apiece and blew .093 and .116 respectively, before the BACtrack also failed with water damage. (Unlike the Breathometer, however, the BACtrack revived the following day.) At that point it was decided to adjourn testing, head to the pub, and maybe get a curry as well.

The morning after the test, conclusions were drawn (as is so often the case). While it had been a fun session, portable breathalyzers have some fundamental flaws as sobriety devices but did yield some very interesting results.

Firstly, the amount of time between drinking and testing was enormously important. Testing 20 minutes after the first beer produced a BAC reading of 0.000, but blowing immediately after the first mouthful raised this to 0.187, and that's just with beer.

When we tried the same thing two drinks later, the BAC reading was 0.082. But blowing immediately after swallowing a mouthful of whiskey upped that to 0.5 – at which point the software told us "you are in danger of dying," with the message displayed on the smartphone in a cheery green font.

Considering these devices use similar tech to those used by law enforcement, this has some implications for anyone who is foolish enough to drink and drive and is pulled over by local police for a sobriety test. If you're stopped before a reasonable time has passed since your last drink, it may be wise to wait for a blood test rather than rely on a breathalyzer on the spot.

Secondly, we concur with the manufacturers that these devices shouldn't be used for judging driving safety. Two testees remarked that, even while blowing under the 0.08 BAC limit, they wouldn'€™t feel safe getting behind the wheel of a car.

So then, could these breathalyzers be of interest as party gimmicks? Well, up to a point. Reliability seemed to be an issue even when just four people used them, and hygiene should also be considered, even though both had removable mouthpieces.

As we saw with the testing data, the speed with which alcohol is absorbed and processed by the body varies significantly. So this kind of device is best used personally to check an individual's sobriety so you can build up a baseline. But you've got to ask yourself: if you're drinking like that, might you have a problem?

Nevertheless, the fact that you can fit what used to be a large and cumbersome piece of machinery onto devices that can be clipped on a belt buckle or put into a back pocket is a wonderful example of how technology develops. Quite how useful they are is another matter.

With regards to the devices themselves, both were easy enough to use. And they could have various practical applications beyond mere sobriety testing. As our esteemed editor observed, "These breath readers would make great random number generators. Just take a couple shots and have a blow!"

Have a safe and happy holiday, everyone. ®