Don’t wait for the police to catch you drunk

Did Santa give you a breathalyzer for Christmas? Should your favorite drinkers have one for New Year’s? According to USA Today, you can buy a disposable one for a single use for about $3; a high-end digital model costs $299.

Companies are making the devices convenient. Some fit on a keychain. Some connect to iPods or iPhones. Some have clocks, calculators or flashlights built in. But how accurate are they? As accurate as what police use? Accurate enough to tell you whether to drive or call a cab? Simple enough that a drunken person could use it properly? Just what is their purpose?

Breathalyzers measure the amount of alcohol in your breath when you exhale. Different jurisdictions set different blood alcohol levels to determine whether a driver is impaired. In Maryland, a level between .04 and .08 is considered driving under the influence; .08 or higher is driving while intoxicated. But if you’re younger than 21, a reading of .02 is grounds for a $500 fine and license suspension.

This makes it seem clearer than it really is. AAA and manufacturers disagree on the accuracy of personal test devices. Also, when you take the test matters, too: If you gulp a drink for the road, its alcohol doesn’t immediately show up in a reading; tests taken sooner than 20 minutes after a last drink won’t measure the peak of intoxication. Experts don’t even agree on the usefulness of measuring blood alcohol levels.

Breathalyzers sometimes are praised as at least a guide for sensible behavior. Parents and schools use them to check youngsters for any amount of drinking. Some bars provide the devices, but you hear talk of patrons competing to see who can get the highest level.

According to the USA Today article, the Food and Drug Administration has approved 21 models, with consumers spending $150 million on them in 2009.

Relying on a designated driver might be cheaper, in more ways than one. But if a personal breathalyzer convinces a drinker to get out from behind the wheel instead of driving away, everyone wins.