Locations
Southern California
4425 Jamboree Road
Suite 265
Newport Beach
CA 92660
Tel: (949) 748-6991
Fax: (949) 748-6994

Northern California
900 G St
Suite 300
Modesto, CA 95354
Tel: (209) 529–1112
Fax: (209)-529-1116

Are breathalizers accurate?

A breathalyzer (or breathalyser) is a device for estimating blood alcohol content (BAC) from a breath sample. "Breathalyzer" is the brand name of a series of models made by one manufacturer of these instruments, but has become a genericized trademark for all such instruments. Intoxilyzer, Intoximeter, AlcoScan, Alcotest, AlcoSensor, Alcolizer, Datamaster are the other most common brand names in use today. The U.S. Government's National Highway Traffic Safety Administration maintains a "Conforming Products List" of breath alcohol devices approved for evidentiary use, as well as for preliminary screening use.

These instruments however are not without their ability for error. Breath testers can be very sensitive to temperature, for example, and will give false readings if not adjusted or recalibrated to account for ambient or surrounding air temperatures. The temperature of the subject is also very important.

Also your breathing pattern can also significantly affect breath test results. One study found that the BAC readings of subjects decreased 11 to 14% after running up one flight of stairs and 22–25% after doing so twice. Another study found a 15% decrease in BAC readings after vigorous exercise or hyperventilation. Hyperventilation for 20 seconds has been shown to lower the reading by approximately 32%. On the other hand, holding your breath for 30 seconds can increase the breath test result by about 28%.

Lastly one of the most common sources of error in breath alcohol analysis is simply testing the subject too early—while his or her body is still absorbing the alcohol. Absorption of alcohol continues for anywhere from 45 minutes to two hours after drinking or even longer. Peak absorption normally occurs within an hour; this can range from as little as 15 minutes to as much as two-and-a-half hours.

Failure of law enforcement officers to use the devices properly or of administrators to have the machines properly maintained and re-calibrated as required are particularly common sources of error. However, most states have very strict guidelines regarding officer training and instrument maintenance and calibration.