Anyone who thinks it cool to be driving round ****ed needs castration
Fixed.
Drink driving - got away with it?
- Thread starter salami1212
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Fixed.
Think that pretty much answers the question
No, grassing him up would have done squat, the police would've just said nothing they can do. Event's been and gone, they have no evidence, and they're hardly gonna trail him til he does it again. On the other hand, grassing him up about a new offence about to take place, is something entirely worthwhile, as there's something they can do about it.
Soldato
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The device measures alcohol content relative to oxygen levels in the air mass flow rate. Brushing teeth/chewing gum will not reduce the chances of getting off when doing the breathe test.
Your friend is a moron.
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like what?
I don't know, films, the bill, Road wars, cops on cameras.. even mythbusters or someone done tests to see if anything would alter the reading..
and of course it wouldn't because the alcohol isn't coming from your teeth, its coming from your blood back out your lungs.
quite simple innit.
Breathe heavily and rapidly for a short while before taking the test. It will cause a reduction in the reading.
Soldato
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Why would that change the reading?
I would guess that he (or someone he read) is assuming that the vapour accumulates in the lungs and this will flush it out. Except AFAIK it doesn't accumulate: if it did then your body would just reabsorb it. Any alcohol vapour will be in equilibrium with your blood. All that will happen if you try this is that you will get light-headed. Not to mention the fact it will look a bit obvious to the fed holding the breathaliser.
Then there's the fact that most cars currently do NOT have evidential breathalisers, just indicative ones, so it's back to the station for a proper test anyway. Followed by a second one. You get the lower reading, but if the two were wildly different I assume that they'd do a third then leave the lawyers to sort it out.
M
Both CO2 and alcohol are highly soluble across the lung membrane. The reason breathing rapidly and deeply (hyperventilation) makes you feel light-headed is because of a drop in blood CO2 levels. In ordinary breathing, you breath out a CO2 concentration of about 4% (atmospheric concentration 0.04%); when you hyperventilate, you breath out a lower CO2 concentration, thus maintaining a greater concentration gradient between the lungs and the bloodstream, causing CO2 transfer to happen more quickly, thus lowering the concentration in the blood (thus when hyperventilating, breathing into a paper bag maintains CO2 concentration and stops you passing out).
Since CO2 and alcohol are chemically similar, it would make sense to me that a similar thing would happen to your blood alcohol concentration - yes, hyperventilation probably would cause a lower reading. Unfortunately, you'd feel light-headed/dizzy from low CO2 before having any real effect on alcohol breath levels, and that will only make you appear more drunk, especially if you then pass out!
If the two readings are wildly different, I presume it would either be rising if you only just stopped drinking (alcohol's absorbed very quickly so it would have to be *just* stopped), or because you're metabolising it (about 1 unit/hr median). But as you said, their meters are not evidential, and they need a blood/urine test to confirm.
I meant if you tried the same game at the police station and it actually did work (which I still doubt) for the first test. The alcohol would rapidly rise again, causing the second test to appear bigger (but actually simply more accurate). The two tests are done in quick succession, so no chance to hyperventilate between the two.
But I'm not sure what you mean by CO2 and ethanol being chemically similar?
M
Ah yes, I see what you mean - you'd have to hyperventilate before each breath test.
CO2 and ethanol are both lipid-soluble, so they cross the blood-air membrane very easily (cell membranes are made from phospholipids, so lipids can simply diffuse through, whereas polar substances such as glucose need special transporter proteins that span the membrane). That's one of the reasons alcohol's absorbed so quickly when you drink it.
Of course - as the blood alcohol returns to its previous levels (by diffusing out of cells etc), which doesn't take very long, the concentration gradient between the blood and the air in your lungs is restored, so the alcohol content of the air you breath out is restored. A contributing factor is that your drive to breath comes from blood CO2 concentration alone until the O2 drops very low, so if you hyperventilate you will then find you have no desire to breath for quite some time - this allows the alcohol (and CO2, irrelevantly) concentration to build up more quickly than if you force yourself to keep breathing normally after hyperventilating. I'd be surprised if it was as long as 30s actually.
Edit: Disclaimer - you should not hyperventilate and hold your breath after! Because the drive to breath comes from CO2 levels, you will be able to hold your breath for several minutes at least, and you may give yourself brain damage from low oxygen levels before you *have* to breath again.
That obvious enough?
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Just tried this, it's true.
