DriveSmartBC - What Would My BAC Be?
 

If you are a driver who will not say no to alcohol prior to driving, BC's new Immediate Roadside Prohibition (IRP) makes it critical to understand how drinking affects your blood alcohol concentration (BAC). How many standard drinks, 12 ounces of beer, 5 ounces of wine or 1.5 ounces of hard liquor, can you consume and still not be over the 50 mg% (.05) level? More importantly, if you continue to imbibe, will your BAC rise, fall or stay the same?

I am a 180 pound (82 kg) male with no health issues that affect my ability to metabolize alcohol. If I consume 3 drinks in an hour, my peak BAC will be 50 mg%. The peak will occur about 40 minutes after I stop drinking although this may be affected by the consumption of food which can extend the absorption period. I have to limit myself to 2 drinks in the first hour to avoid passing the limit and build in a bit of a safety factor.

My body will eliminate about 15 mg% (.015) from my BAC each hour. This means that I can keep my BAC at the level of 2 drinks by drinking a bit more than one drink each hour after the first hour. Drink more than that and it will rise, less and it will fall.

Not all of us are 180 pound males, so let's take a look at a 120 pound female and a glass of wine. This will produce a BAC of 27 mg% (.027) in her, so she had better consider stopping there. She must also consume less than one more glass of wine each hour after that to remain at this level.

Given that there is some variability in everyone's ability to absorb and eliminate alcohol and doing these calculations can be problematic, it would probably be wise to stop at one or two at most depending on your size and sex. Otherwise, it's time for a taxi, designated driver, transit or shoe leather!

Reference Links

This is one thing that many people don't take into consideration when drinking, and then waiting several hours before they drive:

BAC calculator

http://caaneo.ca/about/blog/blood-alcohol-calculator


x3 341ml 5% beers within an hour 0.065 = gg
x3 341ml 5% beers within 2 hours 0.053 = gg
x2 341ml 5% beers within an hour 0.0393

I still think it would be a lot more convenient, if a new law was added stating that any establishment which serves alcohol must have a breathalyzer handy (probably near the entrance/exit) which a staff member can provide should someone want to test themselves prior to leaving.

They would of course have to be properly calibrated, but considering the markup on alcoholic beverages at restaurants/bars/clubs I don't think this would be too unreasonable...

The problem is that the instrument would have to be maintained and recalibrated on a regular basis and the test administered correctly by a trained operator who had kept the subject under observation. Otherwise you would have someone who slammed 4 doubles in a short time, took a test that showed below legal limits, then started a long period of driving. The driver could be stopped a bit later or crashes due to his rising levels of impairment and the club is on the hook because it told him he was sober to drive. I cannot see any bar volunteering to guarantee sobriety levels.

It wouldn't be too hard to at least have the hosts at restaurants and a manager or whoever at a bar trained to administer the test. They should also be able to tell from the billing or at least somewhat keep track of what drinks you've had at what time, as well as asking the person when they took their last drink. Lastly they could have a basic waiver/disclaimer that states that while the establishment is administering the test, they are in no way liable etc etc.

It may be less practical/useful to have at a club, and typically when people are drinking there, they're drinking larger amounts. But if you're out at Boston Pizza for a birthday or at the bar to watch the game, I think this would be a good idea, as after a few drinks and such, you're more likely to be in a mental gray area as to what your BAC should be.

Waivers are virtually worthless when it comes to huge liability lawsuits. We are talking about "permitting" people to drive after consuming liquor, a hugely risky occupation. It would take a person trained to the same levels as law enforcement and even then the lawsuits would follow. I cannot see any club hanging themselves out to dry at the mercy of an employee who is administering the tests. Even if the test was administered properly, what is to stop the drunk driver consuming more alcohol after the test and blaming the resulting crash on the club. The club would have to prove the driver consumed more, to absolve themselves. You know that will happen....the "last drink defence" is a classic Cdn legal tactic.

Well if you sign a quick form, and blow a certain level, but later crash with a higher BAC, shouldn't that be obvious that they drank more later on? People can't sue the police if they go through a roadblock okay, but drink more later on and crash, can they?

It sucks that this likely wouldn't work, because I think it would be quite helpful if people could get tested BEFORE getting behind the wheel.

You either do the test properly and accurately..or not at all. To give someone false expectations of sobriety because of an inaccurate test will lead to major problems for everybody. In this 'excuse to avoid responsibility" world that is the norm.

From the Liquor Control and Licensing Act:

Breathalizer machine

37 A licensee who installs a breathalizer machine is not liable if the machine malfunctions or is misinterpreted, provided the licensee does not aid in its operation or interpret its results.

The business may put one in, but no one is going to be willing to help you use it.

^there are a few places in and around victoria that have them, but they're horridly inaccurate (180lb male blowing .04 after a pitcher and a half of beer), somehow I think maintenance and calibration have been neglected
They're good for business though, you get lots of 19-25 year olds trying to set the high score :P

It is also important for people to remember that their BAC can continue to rise after providing that sample at the club's exit.

Here's something novel: while some restaurants are complaining about the hit to their business caused by this, others are adapting:

http://ht.ly/2Vie5

No.

BAC can increase as alcohol is absorbed into your blood. Ie, I can pound a 26er of vodka, blow a low BAC mins later, yet within an hour I'll be falling down drunk.

You were at that party too? :blushsmile:

If anything should be illegal, these things should be.

It could easily cause people to believe they are fit for driving.

Anything about pricing? Or will they still charge the same jacked up rate? (or close to it)

Again, not hard to ask "How long ago was your last drink? You need to wait XX for it to be accurate"