Trained and experienced police officers can develop remarkably accurate assessments of individual levels of alcohol impairment. However, it is virtually impossible for the casual observer or a friend to judge another’s BAC without the use of a precision breath alcohol tester.
Making the "do not drive argument" to someone who does not show outward signs of intoxication or who does not consider themselves unfit to drive is more compelling when a breathalyzer shows them to be "over the limit." Even someone who is considering driving but blows under .08 may have drunk enough to have a BAC level that will still be rising after they are on the road.
Driving ability is actually impaired at lower BAC levels than .08. Other countries have set the threshold at 0.05 and impairments in judgment and reaction time begin at even lower BAC levels.
We recommend you never to drink and drive. And never consent to ride with anyone who’s been drinking. Even if their BAC is reliably measured at well under the legal limit, they may be significantly impaired and their BAC level may still be rising.
Breathalyzer measurements can also predict other alcohol related behaviors. Educating yourself about the typical effects of alcohol at different BAC levels can help reduce over drinking. It can also help you predict the physical, mental and emotional path that heavy drinking friends or loved ones may follow. While Individual responses to alcohol differ, the BAC chart below is representative of the stages and effect of alcohol at various breath alcohol concentrations.
All drinkers should recognize that the beneficial effects of alcohol on mood, tension and inhibitions occur at BAC levels well below the legal limit of .08. At .08 and over judgment is impaired for everyone.
|BAC Level||Effects from Alcohol|
|0.02 - 0.03 BAC||
No loss of coordination, slight euphoria and loss of shyness. Mildly relaxed and maybe a little lightheaded.
|0.04 - 0.06 BAC||
Feeling of well-being, lower inhibitions, and relaxation. Judgement is slightly impaired. Minor impairment of reasoning and memory, and less cautious. Your behavior can become exaggerated and emotions (ex. happiness or sadness) felt more intensely.
|0.07 - 0.09 BAC||
Impairment present in everyone. Driving skills such as vision, steering, lane changing and reaction time are impaired along with balance, speech, and hearing. Feelings of Euphoria in some. Self-control and caution are reduced. Riskier behaviors displayed. Judgement, reason and memory suffer. You are likely to believe that you are functioning better than you really are.
|.08 BAC is legally impaired and it is illegal to drive at this level.|
|0.10 - 0.12 BAC||
Significant impairment to motor coordination and loss of good judgment. Speech may be slurred; balance, vision, reaction time and hearing will be impaired. Probably not thinking straight.
|0.13 - 0.15 BAC||
Very obviously drunk. Severe impairment to judgment, perception, and major motor skills. Very slow reaction time. Blurred vision, loss of balance and slurred speech. Feelings of well being starting to be replaced by anxiety and restlessness (dysphoria). Vomiting common.
|At .15 BAC you are 380 times more likely to be in a fatal crash than you are sober. (Relative Risk of Fatal Crash Involvement by BAC, Age, and Gender, 2000)|
|0.16 - 0.19 BAC||
The drinker has the appearance of a "sloppy drunk." At this point, most drinkers begin to feel incapacitated. Many social drinkers will pass out. Nausea begins to set in and the drinker has difficulty focusing on any object.
|The average BAC among fatally injured drivers is 0.17, which is also the average BAC nationally for persons arrested for drunk driving. (Century Council)|
Out of it. Confused. Dizzy. Requires help to stand or walk. If injured may not feel the pain. Nausea and vomiting. The gag reflex is impaired and you can choke if you do vomit. Blackouts are likely.
All mental, physical and sensory functions are severely impaired. Near total loss of motor function control. Increased risk of asphyxiation from choking on vomit and of seriously injuring yourself by falls or other accidents.
|0.30 - 0.40 BAC||
Extremely life threatening. You have little comprehension of where you are. You may pass out suddenly and be difficult to awaken. Complete unconsciousness. Coma is possible. This is the level of surgical anesthesia. Death may occur.
|Over 0.45 BAC death will occur in most people.|
Another educational tool that simulates the effects of alcohol on visual and physical impairment are "Drunk Buster Impairment Goggles." These goggles are popular with schools and other organizations for alcohol education and awareness training. Each goggle simulates a different BAC level progressing from mildly intoxicated through dangerous levels of intoxication.
The body (in actual fact the liver) can metabolize only a certain amount of alcohol per hour. No matter how much or how fast you consume alcohol the body can only dispose of it a rate that is generally accepted as being 1 standard drink per hour. Allowing for individual variations in weight, percent body water, percent body fat, and food intake, the amount of alcohol from one standard drink will peak, in your blood stream, within 30 to 45 minutes.
If you have two or more drinks in rapid succession (i.e. in less than an hour) then the liver quickly reaches the point at which it cannot metabolize the alcohol as rapidly as it has been consumed. When this happens the alcohol in your blood, as measured by your breath alcohol content (BAC), will rise.
The rapid consumption of four or five drinks in one or two hours (see binge drinking) overwhelms the liver with much more alcohol than it can handle. As a result BAC rapidly increases and continues to do so until drinking is stopped or decreased to a rate of less than one drink per hour. Excessively rapid drinking as frequently practiced on campus or by those turning 21 will invariably lead to dangerously high BAC levels.
Alcohol leaves the body of at a conservative rate of about 0.5 oz. alcohol per hour or .015 percent of blood alcohol content (BAC) per hour. This is an average rate at which the liver can metabolize (burn off) alcohol. The result is that it can take many times longer to sober up than it took to become intoxicated.
When testing yourself or others, the Lifeguard can help you to get a good idea how long it will take to fully rid your system of alcohol. After measuring your peak breath alcohol content (BAC after it has stopped rising) divide the peak BAC reading by .015 BAC.
Someone with a BAC of .16, or twice the legal driving limit will require over 10 hours to be completely sober and after 5 hours may still not be under the legal driving limit.
Many late night revelers never think about the time it takes to sober up. You place yourself or someone you care about at great risk by driving the morning after without knowing your BAC. For example; if your breath alcohol content after an evening of heavy drinking is .20 BAC when you finish drinking at 1:00 AM, you may not be under the legal driving limit of .08 BAC until approximately 9:00AM later that morning.
Using the Lifeguard for a safety BAC test the morning after a night's drinking is a very good idea. In the UK more than a quarter of people who lose their license for drinking and driving do so the morning after their drinking.