Breathalyzers are vital technology in the battle against drunk driving. Law enforcement personnel use them; the ignition interlock is also based on breathalyzer technology. An ignition interlock, or car breathalyzer, prevents a vehicle from starting if the driver has been drinking.
The past few years have seen a boom in the personal breathalyzer. These are hand-held devices that you can blow into to measure your blood alcohol concentration (BAC). The idea is to use them when you are out drinking, so you have an idea of how impaired you are, and how long it will take you to get sober.
In theory, it’s a good idea. Who wouldn’t want to know how long they had to wait before they were qualified to drive a car? The problem is that the results they deliver are not consistent, and therefore not reliable.
Breathalyzers can employ two technologies:
- Semiconductor: a strip of reactive metal is heated and a current is run through it. Alcohol changes the current, and that change corresponds to the amount of alcohol present
- Fuel Cell: platinum electrodes are oxidized by alcohol, generating a measurable current. Fuel Cell breathalyzers are more accurate, and are the type used by law enforcement
Most of the personal devices on the market, including all the tiny keychain ones, are of the semiconductor type. There are some fuel cell devices, but they are at the high end of the price spectrum. A number of them plug into smartphones and employ an app to do the computing of the BAC.
An Achilles Heel: Calibration
Another factor that needs to be considered is calibration. Law enforcement breathalyzers and ignition interlock devices are calibrated on a regular basis, to ensure that the readings are accurate. Most personal breathalyzers cannot be calibrated. This is especially unfortunate for semiconductor devices, which are notorious for losing accuracy as the metal strip inside deteriorates. Fuel cell devices also lose accuracy, and need re-calibration. Some personal device manufacturers do offer a re-calibration service. However, it’s doubtful that most people are going to spend time and money shipping their device to the factory on a regular basis.
Your Results May Vary
Do an Internet search for reviews of personal breathalyzers. Find one of the many reviews written by a writer who has taken a drink (or three) and then breathed into a half-dozen devices. Invariably, the article goes on to cite six different BAC numbers. That should tell you all you need to know.
We are not saying that a good, accurate personal breathalyzer would not have its uses. If you decide to purchase one, spend more money and get the best fuel-cell one you can afford. But be advised that even those devices have disclaimers on the package.
Don’t Say We Didn’t Warn You
If a breathalyzer is labeled for “personal use” or “home use only” it can only mean one thing: the results could well be inaccurate. It might make a fun conversation piece on a Friday night when you’re out with friends. But if you rely on it, and you’re pulled over later, you can be sure of one thing: the police officer will be holding a professional device, ready to use.