How does a Breathalyzer Work?

Malcolm Tatum

Breathalyzers are instruments that are utilized in a number of professions to determine the amount of blood alcohol content by analyzing a breath sample obtained from an individual. The most common application of a breathalyzer is in the profession of law enforcement, with police officers often employing the device to deal with incidences of drunk driving.

Consumer Breathalyzer tests allow a driver to estimate whether he would pass a Breathalyzer test if stopped by a law enforcement agent.
Consumer Breathalyzer tests allow a driver to estimate whether he would pass a Breathalyzer test if stopped by a law enforcement agent.

While the term breathalyzer actually refers to a particular make and model of blood alcohol content analyzing equipment, the word has come to be considered a common name for any devices that perform this type of function. Smith and Wesson produced the first breathalyzer, but today there are dozens of different models on the market. In all cases, any form of the breathalyzer must meet a stringent set of standards, since the results of the analysis must be accurate within in order to be acceptable in a court of law.

Police often use breathalyzers on suspected drunken drivers.
Police often use breathalyzers on suspected drunken drivers.

The breathalyzer works on the principle of estimating the blood alcohol content of an individual based on a sample of breath that is obtained from the suspect. When a police officer pulls over a driver on the suspicion that the individual may be intoxicated, it is not uncommon for the officer to ask the driver to take what is known as a field sobriety test. Essentially, this involves using a hand held breathalyzer.

The driver exhales into the device, which then uses electrochemical fuel cell technology to identify the elements found in the sample. Some devices also make use of what is known as infrared spectrophotometer technology, which also helps to identify the presence and percentage content of alcohol in the sample. A reading that if over the legal limit will result in the driver being charged with driving under the influence of alcohol (or DUI). In some jurisdictions, this is also known as driving while intoxicated (DWI).

There are also breathalyzer models that are available to the general public. Many businesses that serve alcohol keep a breathalyzer on hand to test patrons that appear to be too intoxicated to drive. Loved ones of recovering alcoholics may also keep a unit handy to periodically test the friend or relative as a means of helping the individual stay sober. However, it should be noted that many of these smaller devices do not have the same level of accuracy found with the breathalyzer models used by law enforcement.

The legal limits for DUI or DWI may vary by state, but are generally around .08 percent.
The legal limits for DUI or DWI may vary by state, but are generally around .08 percent.

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Discussion Comments


I've heard that there are ways that you can "trick" a breathalyzer, but they all sound kind of urban-legendy to me. Especially now knowing how a breathalyzer works, I just can't see how you could really fool one. Of course, there's always somebody with the story about their cousin's friend's brother who successfully fooled the breathalyzer, but has anybody seriously ever done it?


@Comfyshoes - I agree. I think that after the first offense the person charged with the DUI should be forced to buy a breathalyzer that will not allow their car to start.

I heard that those can be pretty expensive too. They are over $1,000, but at least we will know that the person will not be able to drive drunk. I think that when you take risks like that you forfeit your right to drive.

I also think that the media through many of the motion pictures likes to glamorize excessive drinking. In fact many television shows do this as well. The drunk is always the life of the party, but what people don’t realize is how destructive this can be.

When I was a teenager, this kid that I worked with that was about the same age as me and he was killed by a drunk driver. This eighteen year old lost his life because someone decided that it was more important to drink and drive than to find a designated driver or taxi.

Once someone is gone there is no bringing them back. I used to feel so sad for his parents that still continued to shop at my grocery store.


I heard that some states are requiring those with prior DUI’s to buy a digital breathalyzer that is actually attached to the ignition of the car.

The driver then has to do a breathalyzer test in order to see if he or she can operate the car. If the breathalyzer reveals that there is a blood alcohol content then the car won’t start. I think that this is an excellent idea because driving is a privilege and people that drive drunk should not be allowed to drive that way ever again.

It is amazing that many of the DUI’s fall under the misdemeanor category. In fact it only gets upgraded to a felony if you kill someone on your first offense. I think that whether you kill someone or not all of the charges should automatically be felonies. We should not give someone a break and charge them with a misdemeanor because they didn’t kill someone in the process. If these crimes were dealt with more harshly, they would not occur as often.

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