NSYNK
...the 1 hour 1 unit is only a guideline as food, excercise, sweating in a sauna etc all have effects...
An incorrect statement and a very dangerous assumption if anyone decides they want to try to calculate when they will be safe to fly or drive.
Exercise, cold showers, coffee, food taken before, during or after alcohol intake does not affect the volume of alcohol in the bloodstream, or the reduction of it.
Alcohol will leave an individuals body at roughly 1 unit per hour, the exact figure fluctuates but depends on the individual. You cannot eat or exercise it out... those activities may make you feel better or more 'with it', but they do not get rid of the alcohol.
In fact it could be argued that if you have a large meal, your body is less capable of getting rid of alcohol efficiently as it is also having to digest a meal...
Anyone who is considering trying to calculate how long it will take them to clear their system should be very cautious.
Alcohol starts to disspipate as soon as you start driniking it, so even as you drink, you will be getting rid of some units. 1 unit per hour is a good base to work from, but don't try to work out to the nearest 20 mins or so when you will be 'safe'.
Use the 1 unit per hour rule and give yourself an added 2 or 3 hours just to be (more) sure.