Are Breathalyzers Accurate?

Breath analysis is the most common method in determining a person's breath-alcohol-concentration (BrAC). The Department of Transportation has determined that many breathalyzers, when meeting DOT guidelines are able to be used in the screening of alcohol to determine an individual's blood-alcohol-concentration (BAC).

Technological advances in digital alcohol testers or breathalyzers in the last decade has allowed alcohol breathalyzers to see a major rise in use when testing for alcohol. Sensor technology, software analysis, heightened quality, and more innovative designs have helped these breathalyzers close the gap with alcohol blood tests. We will explore the different technologies and methods that are used and what type of accuracy you can expect from consumer and professional breathalyzers.

Blood Alcohol Test

A blood test is the most accurate way to determine your alcohol concentration and is used by courts around the world as evidence in legal proceedings. A blood test is intrusive and costly, so access to a blood test is out of reach for most. A hospital or clinic trained in performing blood tests, take blood from a person's vein and can send it out for analysis. If you are given a blood test for alcohol, you can feel confident that the result is accurate.

Portable Alcohol Breathalyzers

The portable breathalyzer is an effective tool in determining your BrAC, but you should exercise caution with any breathalyzer test. There are many factors that can alter your BrAC and provide a false positive or negative.

Sensor Technology

Fuel Cell sensors are not a new technology, but recent advances in production has led to a range of affordable fuel cell options. The fuel cell breathalyzer is typically the most accurate method of testing and usually has a margin of error of +/- 0.005% at 0.08% BAC. Be aware that all fuel cells are not created equal. As breathalyzers are becoming more popular, many companies are rushing to produce fuel cell sensors, though many of them have not perfected this process.

The most common sensor technology used in most breathalyzers is the semiconductor sensor. Semiconductor sensors use a tin-oxide gas sensor to measure BAC. Like fuel cell sensors, there are varying quality of sensors. Look for devices from South Korea and Japan, as they are the early pioneers of semiconductor sensors. Typically you should expect a margin of error of +/- 0.01% at 0.08% BAC. Semiconductor sensors are subject to false positives when operated by individuals who are diabetic or on an extremely low carbohydrate diet. Semiconductor sensors found in devices like the AlcoMate line of breathalyzers can be expected to perform at law enforcement levels.

What makes a Breathalyzer not accurate?

There are many outside factors that can contribute to a Breathalyzer giving a false positive or inaccurate reading. Here are the most common reasons preventing an accurate breathalyzer from functioning correctly.

• Calibration - Breathalyzers are incredibly sensitive instruments, and require periodic calibrations. As the sensors are exposed to alcohol, they lose their sensitivity over time. Some more advanced breathalyzers like the Alcoscan AL7000, are able to avoid the calibration process by using a replaceable sensor module.
• Alcohol In the Mouth - Alcohol still present in the mouth can easily produce false positives. With any Breathalyzer, one must wait at least 15 minutes since their last drink before testing. Even trace amounts of alcohol in the mouth, can register a much higher reading then what a blood test will show. Users should also watch out for alcohol found in many common mouthwashes.
• Outside Factors - When using a breathalyzer, it's important to be in a clear atmosphere, free from smoke, paint fumes, and other chemicals. These gases can trigger a false positive in some breathalyzers.