Interesting Facts About Alcohol
One of the most common causes of falsely high breathalyzer readings is the existence of mouth alcohol. In analyzing a subject's breath sample, the breathalyzer's internal computer is making the assumption that the alcohol in the breath sample came from alveolar air—that is, air exhaled from deep within the lungs. However, alcohol may have come from the mouth, throat or stomach for a number of reasons. To help guard against mouth-alcohol contamination, certified breath test operators are trained to carefully observe a test subject for at least 15-20 minutes before administering the test.
The problem with mouth alcohol being analyzed by the breathalyzer is that it was not absorbed through the stomach and intestines and passed through the blood to the lungs. In other words, the Breath Analyzer is mistakenly multiplying the result. Consequently, a very tiny amount of alcohol from the mouth, throat or stomach can have a significant impact on the breath alcohol reading.
Recent Drinking is the main cause of mouth Alcohol. After consuming alcoholic drinks alcohol resides in the mouth until it evaporates or is removed by eating food and rinsing. This is the reason you are instructed to wait at least 15 minutes since your last drink before conducting a breath test, to avoid mouth alcohol. Also mouthwash can give a subject a false alcohol reading. Listerine contains 27% alcohol and without rinsing your mouth of this can give false readings.
Other than recent drinking, a common source of mouth alcohol is from belching or burping, or in medical terms "eructation". This causes the liquids and/or gases from the stomach—including any alcohol—to rise up into the soft tissue of the esophagus and oral cavity, where it will stay until it has dissipated.
Acid reflux, or gastroesophageal reflux disease, can greatly exacerbate the mouth alcohol problem. The stomach is normally separated from the throat by a valve, but when this valve becomes herniated, there is nothing to stop the liquid contents in the stomach from rising and permeating the esophagus and mouth. The contents—including any alcohol—are then later exhaled into the breathalyzer.
Mouth alcohol can also be created in other ways. Dentures, for example, will trap alcohol. Periodental disease can also create pockets in the gums which will contain the alcohol for longer periods. And recent use of mouthwash or breath freshener—possibly to disguise the smell of alcohol when being pulled over by police—contain fairly high levels of alcohol.
If you drive after drinking alcohol or taking other drugs you are more likely to be involved in a crash. Alcohol is absorbed quickly into the blood and travels rapidly to all parts of the body. It affects your brain’s ability to make judgments and process information. It also impairs your consciousness and vision too. Consuming alcohol prior to driving increases one’s crash risk. Studies have shown that drivers are twice as likely to crash with a BAC of 0.05g/100ml, seven times as likely to crash with a BAC of 0.08g/100ml, while a BAC of 0.15g/100ml increases the probability of a crash by 25 times 3.
Intoxicated drivers involved in fatal crashes are three times more likely to have been speeding than sober drivers 4. The initial introduction of RBT in Western Australia in 1988 is reported to have had an immediate impact on road crashes, decreasing the number of fatal crashes by approximately 25%.
How does alcohol affect your driving?
You don’t have to be drunk to be affected by alcohol. No one drives as well as usual after drinking alcohol, even though some people may look and act as though they are unaffected. Alcohol is a depressant drug that affects most areas of the brain.
Slows brain functions so that you can’t respond to situations, make decisions or react quickly.
Reduces your ability to judge how fast you are moving or your distance from other cars, people or objects.
Gives you false confidence – you may take greater risks because you think your driving is better than it really is.
Makes it harder to do more than one thing at a time – while you concentrate on steering, you could miss seeing a red light, cars entering from side streets or pedestrians.
Makes you feel sleepy or fatigued.
You cannot compensate for the effects of alcohol on your brain.
Staying under the limit
Estimating your BAC is often inaccurate because:
The alcohol concentration of drinks vary from 2.5 percent (eg light beer) to over 40 percent (eg vodka, whisky).
Beer may be served in pints, schooners or middies.
Wine glasses may vary in size from 100 to 280mls. Many other drinks come in non-standard sizes.
Factors such as your gender, size, weight fitness, health and liver function will all affect your BAC.
Also, the rate at which alcohol is eliminated from your system varies from person to person.
So, don't try to estimate your BAC. Measure it. The RTA recommends using an Australian Standards approved (AS – 3547) breath testing device. (See ADT’s BTA30DAS)
Alcohol must not be consumed for at least 15 minutes before testing because alcohol in your mouth will give an artificially high reading.
Your BAC will rise for up to 2 hours after you stop drinking.
If you go out drinking and have a big night you may still be over the limit the next day so you may need to take another test in the morning.
TM The Australian StandardsMark is a registered trademark of SAI Global. For more information
A common myth is that breath testers can be "fooled" (that is, made to generate estimates making one's blood alcohol content appear lower) by using certain substances. An episode of the Discovery Channel's MythBusters tested substances usually recommended in this practice—including breath mints, mouthwash, and onion—and found them to be ineffective. Adding an odor to mask the smell of alcohol might fool a person, but does not change the actual alcohol concentration in the body or on the breath.
Products such as mouthwash or breath spray can "fool" breath machines by significantly raising test results. Listerine, for example, contains 27% alcohol; because the breath analyzer will assume the alcohol is coming from alcohol in the blood diffusing into the lung rather than directly from the mouth, it will apply a "partition ratio" of 2100:1 in computing blood alcohol concentration—resulting in a false high test reading.
Factors affecting your BAC
The more you drink, the higher your BAC. But two people who drink the same amount might register quite different BACs. There are many factors that will affect this, including:
A smaller person will have a higher BAC than a larger person because the alcohol is concentrated in a smaller body mass.
Someone with an empty stomach will reach a higher BAC sooner than someone who has just eaten a meal. Food in the stomach slows down the rate at which alcohol passes into the bloodstream.
People with a lot of body fat tend to have higher BACs because alcohol is not absorbed into fatty tissue, so alcohol is concentrated in a smaller body mass.
After drinking the same amount of alcohol, a woman will almost always have a higher BAC than a male.
Because of all these variable factors, counting the number of standard drinks you consume can only give a rough guide to your BAC. For more detailed information about alcohol and how it effects you, please see the Australian Drug Foundation website.
It is safest not to drink alcohol at all if you are going to drive. The more alcohol you have in your body, the more risk you have of crashing.
· At 0.05% Blood Alcohol Content (BAC), your risk of being involved in a road crash is double that of a 0.00% reading.
· At 0.1% BAC your risk is more than seven times as high of being involved in a road crash, than at 0.00%.
· At 0.15% your risk increases to 25 times that of driving at 0.00%.
AUSTRALIAN FEDERAL POLICE