FOR drivers who want to test their own blood alcohol levels before they get behind the wheel, there are a wide range of options, from hand-held personal breath analyzers to disposable self-test devices.

There are breath analyzer vending units mounted to the wall in some bars and also personal digital analyzers like the $100 AlcoHawk ABI that can give a readout of approximate blood alcohol content up to 0.40 gram per deciliter, a level usually considered fatal.

Disposable units include the Checkpoint tube, about $22 for a package of nine, a blow-through test that changes color if alcohol is present at a level of 0.08 or more. After a person blows through the tube for 12 seconds, results appear in about two minutes. Another option, a test strip called Alco-Screen, measures saliva and shows color changes that correspond to different alcohol levels. About $2 each.

Those in the interlock field warn, though, that drinkers need to be cautious about informal tests, which often vary by up to 0.02, which means the reading from your device may not stand up to a police officer’s version.