It’s a familiar scene – a man or woman, obviously three sheets to the wind, saying, “I’m fine, leave me alone, I can do this.” What they think they can do is walk to the door, pour another beer – or drive home. That’s the frightening paradox of alcohol: the very thing that makes you unable to drive safely makes you unable to tell that you’re unable to drive safely. It’s a paradox that kills about a thousand Canadians a year.
It’s a rare person who knows the exact point at which to say, “That’s enough – no driving for me tonight.” Most people go beyond that limit somewhat, and some go considerably beyond it. Just for the record, here are the numbers you need to know.
Blood Alcohol Concentration by the Numbers
A long time ago scientists figured out a way to measure how much alcohol was in your blood by figuring out how much exited through your lungs. It appears there’s a pretty steady relationship between the two. It’s called blood alcohol concentration (BAC) and it’s measured by a number.
- .02 BAC. Relaxed. You probably feel okay to drive, since your coordination is still all right. Whatever shyness you have has diminished. You might feel a bit lightheaded, though, which isn’t the best way to drive.
- .05 BAC. Feeling no pain. The alcohol has taken off. Anyone watching you closely would be able to tell you’ve had something to drink, though it hasn’t diminished your senses a lot. You’re the life of the party, cheery and intense. But you’re not too caution. In the bar, this means you might blurt out something inappropriate. On the road, it means you might make a left turn when you don’t have enough time.
- .08 BAC. Drunk. You might not consider yourself intoxicated, but your balance is off, and you’ll forget words and stumble over sentences at times. Your reaction times are slower than normal. If you had your vision or hearing tested, they’d be worse than normal. This is not a time to be driving, and the crash statistics prove it.
- .12 BAC. High. You’re in the “movie drunk” phase now, with blurred vision and serious motor impairment. Since you can’t walk straight, how are you supposed to drive?
- .16 BAC. Hammered. You’re getting sick, and people will have a hard time understanding what you are saying when you talk. Yet people have been known to get in their cars and drive with this much, or more, alcohol in their blood.
- .20 BAC. Blacking out. At this point you might not remember what happens the next day, and you might not want to. Nausea is common.
- .30 BAC. Alcoholic poisoning. Generally you’re in a stupor and can’t be awakened.
- .40 BC. Coma and Death. People have been found behind the wheel with this amount of alcohol in their systems as well.
Blood Alcohol Concentration Drink by Drink
Now that you know how much alcohol does what, it pays to know how much you can drink to reach an unsafe BAC level. It’s not easy to say, because it’all depends on your size, your sex, your age, your fitness level, and probably a few factors we don’t even know about. But we can use the first two factors to get a general idea of how many drinks put you in the danger zone.
|MEN Body Weight (kg)|
|WOMEN Body Weight (kg)|
One of the sad facts of life is that women have a lower tolerance of alcohol than men, and many smaller women might not be able to drive after one drink unless they wait a good while for the alcohol to leave their systems.
How much alcohol is safe to have in your system if you’re driving? There’s no sure answer. The legal limit is .08, but obviously a lot less alcohol can make a difference in your driving, and you can even be arrested for DUI with less than .08 in your system, if you are judged to be impaired at the scene. Also, some provinces have a “warn range” of .05, over which penalties can be imposed. Keep in mind that any amount of alcohol can affect your driving, so the best option really is not to drink at all. Second best is allowing plenty of time for alcohol to leave the system – about an hour per drink – before getting behind the wheel.
Also remember that other factors, such as fatigue, food, your size and weight, and your metabolism, all change how alcohol affects you.
So spend a little time with the numbers, and know the ones that apply to you. They’re all that stand between you and the fatal decision that so many Canadians make every year.