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Breathalyzers – Understanding How They Work

healthcare monitorsThe Basics

Strait Whiskey On An Empty Stomach

When ingested, alcohol passes from the stomach into the small intestine, where it is rapidly absorbed into the blood and distributed throughout the body. Because it is distributed so quickly and thoroughly the alcohol can affect the central nervous system even in small concentrations.

Strait alcohol such as whiskey, vodka, etc. consumed on an empty stomach will enter the bloodstream more quickly than a drink mixed with milk drunk after a full meal. This doesn’t mean you will become more intoxicated from the straight whiskey or vodka, just that the effects of the alcohol will be felt more quickly.

Alcohol In Your Breath

Once in the blood stream alcohol circulates through the body and generates the usual effects of alcohol on the body and brain. As the blood passes through the liver it is gradually filtered from the bloodstream, reducing at each “pass” until there is no longer any residual alcohol in the body. It also passes through the alveoli in the lungs, and as you breath and the oxygen passes into the bloodstream, so does some of the alcohol in your blood “evaporate” into the air in your lungs.

It is this alcohol that a Breathalyser is designed to measure. This is why it is necessary to measure “deep lung air” when using a breathalyser. This is also why it is important not to drink for 20 minutes prior to testing.

Why You Must Wait

If you use a breathalyzer shortly after drinking (without waiting about 20 minutes) the alcohol that remains in your mouth will be blown directly into the detector. It will be read at far higher concentrations than it would if it had passed through the stomach, into the bloodstream, and into the air you exhale.

Breathalyzers can be very useful when used over a period of time to generate a “picture” of how you absorb alcohol. Everyone is different, and factors such as the amount of food in your stomach and your own metabolic rate can dramatically affect the rate at which alcohol is absorbed.

How To Use Your Breathalyzer

The way to get the most from your Personal Breathalyser is to use it regularly to monitor the change in your level of intoxication, rather than looking at a single specific reading. Always wait 20 minutes after drinking or smoking before testing yourself.

Take a deep breath then try to blow steadily and consistently so that you blow the same each time. Be sure to blow until the breathalyzer signals you to stop, usually about four to five seconds. Most units have an audible sound indicating when you have blown long enough. The unit will then take a few seconds to measure your blood alcohol concentration (BAC) and display it on the screen.

Sensor Types

Originally breathalysers were designed around a device called a Fuel Cell. These are relatively expensive to manufacture but are highly accurate and reliable over a wide range. Breathalysers certified for evidential use (known as EBT’s) use these sensors.

In order to produce a more economic device various semi-conductor based sensors have been developed. These use varying levels of software complexity to translate their readings into equivalent values such as BAC%, mg/l and microgrammes. These sensors are more susceptible to drift where the values produced gradually vary as the unit gets older and is used more.

Semi conductor based sensors also have a narrower range of sensitivity and are more complex to calibrate. They are usually calibrated to be most accurate at or close to the “legal limit” of.08 BAC.

Why Recalibration Is Important

It is important that the breathalyzer is re-calibrated when needed (approximately every 200 to 300 blows) by the manufacturer. To eliminate the down-time needed to return a breathalyzer to the manufacturer for re-calibration, there are now two units on the market that incorporate a user changable sensor module. These are the AlcoMate Premium and the AlcoMate Prestige.

Employers and Law Enforcement agencies who must have a reliable and consistent reading over the full range of use should consider fuel cell breathalyzers which are generally priced from about $450.00 to $1,500.00.

An alternative is to use a high-end semi-conductor breathalyzer like the AlcoMate Premium. Because the AlcoMate Premium uses a sensor module that can be easily changed by the user it retains its accuracy indefinately as long as the sensor module is replaced when needed.

Accuracy Matters

Users should also bear in mind that the accuracy of a particular sensor quoted in the specifications has been measured under strict laboratory conditions immediately following calibration. Due to the variations listed above, and particularly the limitations of sampling, it is unlikely that such specific accuracy is likely to be obtained on a repeatable basis by the user “in real life”.

Sensor saturation with alcohol, or contamination with smoke during a test, can quickly destabilize the sensor software and lead to unreliable results. Anyone using a “personal” breathalyzer should leave a substantial margin of error and take into account general factors such as what and when they’ve been drinking – you cannot rely solely on a Personal Alcohol Detector to determine your level of intoxication!

How Alcohol Affects You

In low concentrations, alcohol reduces inhibitions. As blood alcohol concentration increases, a person’s response to stimuli decreases markedly, speech becomes slurred, and he or she becomes unsteady and has trouble walking.

With very high concentrations – greater than 0.35 grams/100 milliliters of blood a person can become comatose and die. The American Medical Association has defined the blood alcohol concentration level of impairment for all people to be 0.04 grams/100 milliliters of blood.

Judgment and coordination can be significantly impaired even with blood alcohol levels of 0.03 (and lower) so the safest practice is simply not to drive or operate machinery when you have been drinking any amount of alcohol.

Today there are some excellent quality breathalyzers available for personal use. They can be a great aid in helping you understand how alcohol effects you or your friends.