BreathKey Frequently Asked Questions

Why choose BreathKey?

Everyone knows that driving while intoxicated can lead to severe consequences. BreathKey breathalyzers are a convenient and reliable way to help determine how much alcohol is in your system.

Currently, the legal limit for blood alcohol content or BAC is .08% in all states in the US. This percentage is down from the previous .10%. Many professionals respected in the medical community have stated this new lower level is still too high.

Although roadside sobriety tests are helpful in determining if a driver is too impaired to drive, they are not exact and far from scientific. The BreathKey models use the most advanced technology to ensure accurate results each time the breathalyzer is used.

BreathKey breathalyzers are the smallest breathalyzers in the world. The BreathKey Model g10 is also the only keychain breathalyzer that uses a fuel cell alcohol sensor, the same type that is used in the professional breathalyzers used by law enforcement. And all BreathKey breathalyzers use a flow sensor for a deep-lung sample, to make sure that you are getting an accurate reading.

BreathKey breathalyzers were developed by the same engineer who designed the breath alcohol ignition interlock systems used by the courts in almost 40 states. 25 years of design experience in the breath alcohol testing field have gone into the development of BreathKey breathalyzers.

BreathKey breathalyzers use advanced technology, and are affordable, accurate and easy to use.

What's the difference among the different BreathKey models?


How do I interpret the BreathKey results? Can it be used to determine if I am safe to drive? Will it prevent me from getting arrested?

Your level of impairment from alcohol depends not only on how much you have had to drink, but on a variety of other factors, including how much you have had to eat, your weight, your gender, how much rest you have had, and your mental state.  While the legal limit is .08% BAC (blood alcohol content), impairment can begin at a level of .04% BAC or even lower.  Everyone responds differently to alcohol; some people may be reasonably safe at a lower BAC level while others may not.

A precaution when using any breathalyzer is to consider what your personal limit may be as well.  Intoxication can occur almost immediately and also progress over several hours of drinking.

For these reasons the BAC results from the BreathKey or from any breathalyzer cannot be used on their own to determine whether or not you are impaired or if you are safe to drive.  Only you can make that determination.

In addition, no breathalyzer can assure that you will not get arrested for driving under the influence of alcohol.  You can be arrested for DUI with a BAC that is less than the legal limit.  Impairment can occur at any point during drinking depending on the individual.

Also note that you could have a higher BAC reading even a few minutes after using any breathalyzer, depending on how much you have had to drink and on when you stopped drinking.  In addition, alcohol residue in your mouth can read at a higher concentration for up to twenty minutes after your last drink.

However, when used properly the BreathKey will give you an accurate measurement of your blood alcohol level.  This can be very useful information when considered together with all of the other factors that can affect whether or not you are impaired.

Remember that it is always safest when you do not drink and drive!

How do I use my Breathkey?

To use your BreathKey, simply press the button on the front of the device.  Your last BAC reading will be displayed, and then WAIT will appear for a few seconds.  Next you will see BLOW, at which point you blow for about 4 seconds, until you hear a long beep.

It’s important that you blow with moderate force until you hear the beep.  Not blowing long enough or forcefully enough can cause the BreathKey to abort the test and make you start over.  Blowing for a full 4 seconds makes sure that the BreathKey will take a deep-lung sample of your breath so that it can provide the most accurate reading.

You will again see WAIT for a few seconds while the device calculates your BAC.  Finally, your BAC level will be digitally displayed.  After about 10 seconds the device will turn itself off.  (see “How does it work”)

As is the case with any breathalyzer, you first must wait about 20 minutes after your last alcoholic drink for the alcohol in your mouth to dissipate and be absorbed into your system.

A breathalyzer analyzes the alcohol content in your lungs.  If you use a breathalyzer immediately after having a drink, the alcohol that remains in your mouth will be blown directly into the breathalyzer. The breathalyzer will then result in a much higher blood alcohol content (BAC) reading than it would if the alcohol had passed through the stomach and intestines, into the bloodstream, and into your exhaled breath (see “How do breathalyzers work?“).

Note that items such as breath spray or mouthwash contain alcohol and these items may result in a higher BAC reading. Waiting 20 minutes after using either of these will allow the alcohol they leave in your mouth to dissipate before testing.

How do breathalyzers work?

Alcohol is absorbed into your bloodstream primarily through the stomach and intestines.  The rate of absorption depends on many factors, including your weight, whether or not there is food in your stomach and your body’s metabolic rate.  Deep within your lungs there are tiny blood capillaries that interface with the air.  This is where the alcohol in your bloodstream is evaporated into your exhaled breath.  The alcohol breathalyzer then determines the content of alcohol in your breath.

Any type of alcohol breathalyzer depends on an alcohol gas sensor to measure the content of alcohol in your breath.  Most professional breathalyzers use a fuel cell alcohol sensor, while most consumer breathalyzer use a less expensive semiconductor sensor. The content of alcohol in your breath is assumed to be directly proportional to that in your blood.

Professional quality alcohol breathalyzers contain a flow sensor that requires that you blow for a minimum amount of time at a minimum flow rate to assure that you expel enough air out of your lungs to get to the “deep-lung” air, where the most accurate alcohol breathalyzer reading can be obtained.  The better quality consumer breathalyzers also contain a flow sensor so that they can obtain a deep-lung sample. All BreathKey models use a flow sensor.

With any alcohol breathalyzer you must wait about 20 minutes after your last alcoholic drink before testing.  This is because any alcohol that is left in your mouth after your last drink is at a very high concentration when compared to the alcohol that is in your exhaled breath.  Alcohol in your mouth will result in erroneous blood alcohol readings, so you must wait for the mouth alcohol to dissipate before testing.  If you choose not to wait at least twenty minutes you may receive a breathalyzer false positive.  This false positive result can occur whether you use an expensive professional breathalyzer or an inexpensive consumer breathalyzer.

What is meant when you say that the BreathKey Model g10 is “FDA Certified”?

The BreathKey Model g10 has passed the Food and Drug Administration’s 510(k) certification process.  This means that the FDA has determined that Model g10 is “substantially equivalent” to other breathalyzers that are already marketed with FDA approval. Essentially, that means Model g10 has passed the testing required by the FDA and it does what the product literature says it does. Model g10 underwent extensive laboratory and field testing in order to get this FDA certification.

510(k) refers to a section of the Food, Drug and Cosmetics Act. The FDA has a submission and control process, wherein particular products, such as safety devices, go through a strict process of evaluation and testing in order to receive FDA approval. Breathalyzers either receive FDA approval or they do not.  There is no rating system involved; the criterion is very black and white.

Breathalyzers used by law enforcement require Department of Transportation (DOT) approval.   The purpose of DOT approval is to make sure that a breathalyzer meets certain accuracy standards set by the DOT in the event that the breathalyzer results are to be used in a courtroom setting. The DOT is not concerned with consumer safety, which is the purpose of the FDA. Some breathalyzers sold to consumers have DOT approval, but DOT approval does not substitute for FDA certification.

What is the difference between a fuel cell alcohol sensor and a semiconductor alcohol sensor?

The BreathKey Model g10 is the only keychain breath alcohol tester to use a fuel cell alcohol sensor, the same type that is found in breathalyzers used by law enforcement. A fuel cell sensor is a low power device that produces a small electrical current when alcohol is present. This current is then converted into a blood alcohol content (BAC) reading

BreathKey Models s10 and s100 use semiconductor sensors. Semiconductor sensors use a small ceramic bead heated up to a high temperature.  When alcohol is present, the electrical resistance of the sensor changes and this change is converted into a blood alcohol content (BAC) reading.

The advantages of fuel cell sensors are that they use very little power, are ready almost immediately, are more stable over time, and rarely give false positive readings.  The usual disadvantage of fuel cell sensors is their cost; however, OmegaPoint has spent years developing its own patented fuel cell sensor technology that has resulted in a sensor that is significantly less expensive to make when compared to conventional fuel cell sensors, yet is reliable and accurate.

The advantage of semiconductor sensors is that they are very inexpensive to make.  The disadvantages are that they use more power, take some time to warm up, are less stable over time and can sometimes give false positive readings.

What is the accuracy of my BreathKey?

The accuracy of the BreathKey Model g10 is ±.01% BAC at .08% BAC.  This means that on average the BAC (blood alcohol content) reading from the BreathKey will be within .01% of your true BAC level, if your true BAC level is .080%.

The accuracy of the BreathKey Models s10 and s100 is ±.02% BAC at .08% BAC.  This means that on average the BAC (blood alcohol content) reading from the BreathKey will be within .02% of your true BAC level, if your true BAC level is .08%.

By comparison, the breathalyzers used by law enforcement officials have an accuracy of ±.005% BAC at .080% BAC, according to the standards set by the Department of Transportation.

If a breathalyzer is used shortly after drinking, without waiting at least 20 minutes, the alcohol that remains in your mouth may be blown directly into the detector.  It will be read at far higher content level than it would if it had passed through the stomach and intestines, into the bloodstream, and then into your exhaled breath.

Remember that all breathalyzers need to be calibrated on a regular basis to maintain accuracy.

Also remember that the results of any breathalyzer test on their own cannot ensure that it is safe for you to drive. Since everyone varies with how they respond to alcohol, only you can make the determination as to how safe you really are.

How long do the batteries last?

If used once a day, every day, the BreathKey Model g10 will last over 5 years – longer if used less often.  This amounts to more than 2500 tests.  The internal battery is not replaceable by the user; however, when you send us your BreathKey Model g10 for a periodic calibration, we will check the battery and replace it if necessary at no additional charge beyond the calibration fee.

BreathKey Models s10 and s100 use alkaline AAA batteries. Depending on use, the batteries will last several months. The batteries used by these models are easily replaceable by the user.

Can my BreathKey be shared?

A breathalyzer that uses a flow sensor will provide a deep-lung sample and give a more accurate reading. Since the air that is deepest in your lungs has the highest concentration of alcohol, a deep-lung sample will provide the most accurate blood alcohol content reading. Breathalyzers with a flow sensor make sure that a person keeps blowing until the breath that is exhaled from the deepest part of the lungs is used for the measurement. All BreathKey models have flow sensors.

BreathKey Model g10 uses direct mouth contact for the most accurate reading.  Many larger hand-held breathalyzers, including those used by law enforcement, use disposable mouthpieces.  While this allows for their use by multiple individuals, there is an inconvenience in that the mouthpieces must be carried around with the breathalyzer, and they must be cleaned or replaced regularly. Since it does not use a mouthpiece, the Model g10 was designed to be a personal device, so for hygienic reasons it is not meant to be shared among individuals.

BreathKey Models s10 and s100 do not require direct mouth contact or use mouthpieces. You simply hold the devices a short distance away from your mouth and blow when prompted. Thus these models can be shared.

What is “% BAC”?

Blood alcohol content or blood alcohol concentration (abbreviated BAC) is the concentration of alcohol (specifically ethanol) in a person’s blood.  BAC is most commonly used as a measure of intoxication for legal or medical purposes.  It is usually measured as a percent (mass of ethanol per mass of blood).   For breathalyzers, it’s assumed that the concentration of alcohol in a person’s breath is directly proportional to the concentration in their blood.

Alcohol is absorbed into your bloodstream primarily through the stomach and intestines.  The rate of absorption depends on many factors, including your weight, whether or not there is food in your stomach and your body’s rate of metabolism.  Deep within your lungs there are tiny blood capillaries that interface with the air.  This is where the alcohol in your bloodstream is evaporated into your exhaled breath.  The breathalyzer then determines the concentration of alcohol in your breath and converts it into an equivalent blood alcohol content reading.

Other ways that alcohol can be detected are through a saliva test, a blood test, or a urine sample.   Although alcohol can be identified using a breathalyzer, the most accurate results are those that are run in a lab, but they take much longer to determine.  If your breathalyzer BAC comes up at or above the legal limit, which is .08%, then a law enforcement official will typically run a lab test and forward your results to a court official.

The benefit of using a breathalyzer is that it can provide immediate blood alcohol content results.  A breathalyzer will not prevent a person from drinking and driving, but it’s a useful tool in determining if you are over the legal limit.

Unfortunately, the number of alcohol related deaths is still too high.  Knowing information about intoxication levels, blood alcohol content and simply your own limits can give you the information you need to make an educated and responsible decision.

What is the % BAC limit for driving?

DWI laws vary from state to state.  Every state in the US currently defines a breath alcohol content (BAC) of 0.08% or higher as criminal when operating a motor vehicle and will cite the driver for driving while intoxicated (DWI).  If the driver of a motor vehicle is under the age of 21, most jurisdictions practice a Zero Tolerance policy, set at 0.010% or 0.020% BAC.

The DWI laws in the state of Texas are different from the DWI laws in Arizona.  An attorney for a drunk driver in the state of New York may use a defense that would work for that driver in New York, but that defense may not even be considered by an DWI attorney in Atlanta.

Many states will site a driver for driving under the influence (DUI) for BAC levels as low as 0.05%.  Recent New Jersey DUI penalties would seem lenient compared to those in the state of Florida.  One Illinois drunk driving lawyer avoided jail time for his defendant altogether when the defendant pleaded guilty in a license suspension hearing for a third offense. DWI laws in Ohio immediately refer the judge to the breath test results, which aren’t automatically permitted in court according to Texas DWI law.

In some states a person’s driver’s license may be taken away on the spot by the arresting officer if the driver refuses a breathalyzer test. This is referred to as administrative license suspension.

Drunk driving cases could be avoided if every educated driver would use the tools readily available to him or her.  Utilizing devices such as breathalyzers and the collective knowledge of the effects of alcohol on an individual can prevent a tragedy.

Remember, all DWI laws state that it is always safest when you do not drink and drive.

For more information on DWI laws, please refer to the DUI/DWI page.

If your question is not covered in these FAQs, please contact us through our site.