What is a Breath Analyzer?

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  • Written By: R. Kayne
  • Edited By: Niki Foster
  • Last Modified Date: 09 October 2019
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A breath analyzer, or breathalyzer, is a battery-operated device that can reveal a person's blood alcohol content (BAC) by sampling the breath. Professional models, not much larger than a deck of playing cards, provide quick, accurate results displayed digitally in a LED window.

Law enforcement has used breathalyzers for many years, but a breath analyzer can also be handy for individuals. Party guests can avail themselves of a breathalyzer to ensure they can legally and safely get behind the wheel to drive home. If the reading is still too high, a simple waiting period can help one avoid a costly DUI (driving under the influence violation) or worse. Institutions and business with policies of random drug testing might use a breath analyzer, especially among employees that are entrusted with the care of others, work with potentially dangerous machinery or operate vehicles.

A breath analyzer can detect BAC because alcohol does not change chemical composition within the body. Instead, it is absorbed by the stomach and intestines to enter the bloodstream. Inside the bloodstream it travels throughout the body, including lung sacs called alveoli, where alcohol molecules are mixed with exhaled air.

The ratio for alcohol found in the breath to alcohol in the blood is 2,100:1. Hence, by measuring the concentration of alcohol in the breath, the analyzer can easily calculate blood alcohol content. The legal limit in most states is 0.08% BAC.


A breath analyzer can be designed to identify alcohol by different means. Many commercial models use "smart dust" or oxidize sensors that, when exposed to alcohol molecules, create electrons and protons which travel down a wire. A microchip measures the electrical current in the wire to calculate the concentration of alcohol. Other models are designed to measure the absorption level of infrared light on different molecules, and still others are based on other chemical principles. A good indication of quality is to look for those approved by the Department Of Transportation (DOT) and the National Highway Traffic Safety Administration (NHTSA).

An approved breath analyzer generally runs about US$100 and can be found online or at finer department stores. A breath analyzer can be a life-saving gift, not only for the one drinking, but for others on the road. Note that very small pocket-sized models are generally considered novelty gifts and may not be accurate.


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Post 5

@cardsfan27 - I have a friend who is a lawyer and handles DUI cases fairly regularly. Like stl156 mentioned, the system of using breathalizers really is flawed. Even when jails order new machines, they come with a warning that the results are only accurate to a certain degree, and weight and lung capacity play a huge rule in the final reading.

There are ways that you can manipulate the system. The way the machine works is by measuring alcohol particles that come from your breath and lungs. If you "hyperventilate" by breathing in and out quickly for a while before blowing into the machine, you can get a reading that is about .05% lower than the real reading because you

expelled a lot of the alcohol from your lungs.

That is why when you see police give someone a breath test, they tell them to keep blowing until they don't have any breath left. In reality, the machine can get a reading after a few seconds, and you are legally entitled to stop blowing at that point.

The only true measure of BAC is a direct blood test. You are always allowed to go this route, but you have to pay for it yourself.

Post 4

@titans62 - I think that is a great idea. Like you said, if it could prevent more drunk drivers from getting behind the wheel, it would be worth it.

I didn't realize how many different types of alcohol testers there were. Are any of them typically more accurate than others? Do jails all have to use the same type, or can they have a choice.

I've never used a breath analyzer, but is there any way to cheat the system, so to say? I have heard a lot of urban myths like holding a penny in your mouth, but I know those don't work. I'm talking about real methods than can fool the machine.

Post 3

I think it would be a great idea for bars to have a breathalizer that people could use as they are leaving to test their blood alcohol.

Obviously, if you have to ask yourself whether you should be driving, the answer is probably no, but I don't think some people really realize the effect the alcohol has had on them. It might be eye opening for some people.

Sure, it would be added cost for the bar or club, but given the cost of drunk driving accidents, maybe it would be worthwhile for states to subsidize the cost of them. Just an idea.

Post 2

I have read there are a lot of potential problems with breath analyzers not being accurate. For example, the article mentions that the ratio of breath to blood ratio of alcohol is 2100 to 1, but that is dependent on the size of the person and other factors.

Besides that, each state comes up with its own ratio to use for legal cases, and legislatures usually set the ratio at 1500 to 1 because of pressure from lobbyists. That means in some states, a BAC of .07 will actually show up as .09. That is the difference between a criminal charge or not.

Drunk driving is not good, but states should at least be using the scientifically accepted protocols.

Post 1

can i get the circuit diagram for a breath analyzer so that i can made it at home please?

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