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Are Breathalyzers Foolproof?

May 16, 2016

A breath analyzer is a small, portable device used to measure the blood alcohol concentration (BAC) in suspected drunk drivers.  Blood alcohol is the concentration of alcohol in a person’s blood. Police officers often use these devices as they are used in the field to detect whether a driver is over the legal limit for alcohol.

A Breathalyzer is a the brand name of one such type of device developed by Robert Frank Borkenstein, but many now use the name of the device to refer to any device that measures blood alcohol content. Some other breath analyzer brands include BACtrack, alcoHawk, and Intoxilyzer 9000.

The Breathalyzer works by measuring the concentration of alcohol in the breath sample. Most breathalyzers use one of three technologies to detect BAC. The three technologies are a semiconductor oxide sensor, a fuel cell sensor or a spectrophotometer.

  • Semiconductor oxide sensor is an ethanol-specific sensor that can measure the subject’s BAC. These sensors have many benefits, including low cost, low power consumption and small size.
  • Fuel cell sensors are also portable, handheld devices and very accurate in testing BAC. A fuel cell measures alcohol content by creating a chemical reaction that oxidizes the alcohol in the sample and produces an electrical current. The more alcohol that is oxidized, the greater the current which determines the BAC.
  • Spectrophotometer technology is used in large breathalyzers often found at police stations. Spectrophotometers work by identifying molecules based on the way they absorb infrared light. The level of ethanol in a sample is measured, and a subject’s alcohol level can then be determined from that sample.

For most models, a person simply blows through the mouthpiece for 5 seconds. The breath analyzer will indicate when to start and stop blowing, and if the sample was not adequate for an accurate reading.

The sensors measure the alcohol level of air in the deep lungs. This value is converted into the corresponding BAC estimate. Testing is most accurate if subjects have not consumed food or alcohol 15 minutes prior to testing to ensure that there is no residual mouth alcohol.

However, many cases have found that breath analyzers and tests can be flawed. The “Honey Bun Test,” for example, measured the BAC after a subject consumed certain foods that contain low levels of ethanol. The tests often showed false positives for alcohol immediately after eating those foods. But in most cases, the false positive effect wears off about 15 minutes after ingesting the food or drink.

These inaccurate readings and false positives call into question the accuracy of the breathalyzer and show that there is a need to perform duplicate tests to ensure that you are getting an accurate reading.

A Breathalyzer can be a valuable tool for measuring BAC quickly, but it isn’t foolproof. There can be many factors that can interfere with an accurate reading, and in the case of any doubt, a blood test is recommended.
If you think you may be a victim of a false positive or a wrongful arrest, find a DWI attorney that can fight – and win – your trial.

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Updated: May 16, 2016 at 10:31 am