How Do Breathalyzers Work?

Man Looking at BreathalyzerThe breathalyzer is an amazingly simple device used to determine the blood alcohol content (BAC) of someone who might be drunk. It’s a common tool used by law enforcement officers checking for drunk drivers. It can be a great device, depending on which side of it you’re on, but how does a breathalyzer work?

In a nutshell, the breathalyzer works by measuring the amount of ethanol in your breath. The word “breathalyzer” is actually a brand-name and registered trademark. But just like the word “Xerox” is now commonly used to describe any brand of copier, all sorts of BAC devices are referred to as breathalyzers.

What Is the Science Behind Breathalyzers?

In 2001, Discovery Networks’ How Stuff Works did an excellent piece on the breathalyzer. Even though the material is 12 years old, it is still relevant today. Nothing much has changed since then in terms of technology or the science of how the device works.

When you consume alcohol, you’re consuming a substance scientifically categorized as being volatile. Volatility doesn’t mean the liquor is going to explode, although the moonshine you got from your old pal Grumpy may; it means that the alcohol separates from the rest of the beverage through evaporation. Furthermore, alcohol is not digested.

The properties of alcohol dictate that it is absorbed by the bloodstream quickly and carried throughout the body. As blood passes through the lungs some of the alcohol covers the various surfaces of the lungs and is expelled during the breathing process.

The breathalyzer estimates how much alcohol is in the blood by measuring how much is on the breath. That measurement is thought to be fairly accurate unless, of course, your breath is bad enough to peel paint even without alcohol in your system.

How Are Breathalyzers Used?

If you’ve never had to use the breathalyzer, trust us when we say it can be humiliating. You have to wrap your lips around this tube and blow, as hard as possible, forcing as much air through the breathalyzer as you can. There is an anode in the device that instantly converts the alcohol into acetic acid. Then there’s a reaction between the acetic acid, oxygen, and the water in one’s breath that creates a measurable electrical charge.

If that all sounds too complicated, all you need to know is that it works fairly well. We say “fairly well” because breathalyzers are not always completely accurate. They only offer an estimate of BAC, which can be later verified through an actual blood test.

Just How Inaccurate Are Breathalyzers?

Ask anyone who’s been convicted of DUI/DWI and he will probably tell you that breathalyzers don’t work at all. But one man’s anger is another man’s justice. Breathalyzers have proven to be accurate enough to at least raise suspicion if a high reading comes back.

However, Professor David Hanson of the State University of New York at Potsdam claims the margin of error for the portable breathalyzer test can be as much as 15%. He further states that as many as 23% of all drivers convicted of DWI/DUI are quite likely victims of breathalyzer readings that were artificially high. The problem is that so many other things can affect the readings.

The first of those things is calibration. Portable breathalyzers used by police officers are the least accurate of all, requiring regular and expensive calibration. If one of these units is not calibrated regularly it can be completely useless in the field, much the same way you are after a few drinks.

Abnormal amounts of acetone in somebody’s system will also throw off a breathalyzer. Diabetics and those on certain types of weight-loss diets regularly have elevated acetone levels. If you’ve been drinking and you’re on a diet, an uncalibrated breathalyzer could tell officers you died of alcohol poisoning hours ago.

Lastly, acid reflux disease and common ulcers often result in ethanol being released from the stomach and the esophagus. This excess ethanol could make it appear as though you’ve been drinking, even if you haven’t. There are other medical conditions also capable of interfering with breathalyzer tests.

Can I Buy My Own Breathalyzer?

We’re not recommending you do so, but you’re free to buy your own breathalyzer at retailers like Best Buy, Walgreens, and WalMart. They’re fairly inexpensive and easy-to-use. If you are planning to buy one, please be responsible with how you use it.

Having your own breathalyzer is not a license to consume adult beverages right up to the point of drunkenness, then get behind the wheel and drive. If you need a breathalyzer to tell how intoxicated you are for driving purposes, you shouldn’t be driving anyway. On the other hand, your very own breathalyzer would come in handy in some situations.

For example, you could inform all of the guests at your July 4th gathering that you’ll be collecting car keys upon arrival. Before you return the keys to a guest you might ask her to submit to a breathalyzer. You can also use the device on your teens when they come home two hours past the curfew. Can you say busted?