|MadSci Network: Chemistry|
Gasoline is roughly 10% ethanol, which is close to the ethanol content of white wine. You would need to inhale the entire contents of a soda can full of gasoline before you would show any appreciable blood alcohol level on a breathalyzer. And at that point you would certainly already be dead, so the breathalyzer would be the least of your worries.
Gasoline contains a lot of nasty things like benzene, toluene, and xylene, none of which is particularly good for you. Breathing concentrated gasoline fumes in an enclosed space can very easily be fatal. If you hear of someone who is worried about being caught "huffing" by a breathalyzer test, get that person some help immediately, before it is too late.
(More information can be found at http://www.mayoclinic.com/health/inhalant-abuse/HQ00923 if needed)
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