I something that has dropped by more than half in the past 35 years really a "crisis"? I think through education and awareness the US has done really well at hitting home the point that drinking and driving is stupid. I don't think this type of technology is the way to go. Everyone person responds to alcohol differently and having a set BAC number is just stupid. Some people can drive fine at .08 while some people can't. The .08 limit is defined by who exactly? Some arbitrary bureaucrat that just decides the limit? No thanks. Why don't we train officers to make a judgement if a person is too impaired to drive instead of having arbitrary BAC limits. A person in Germany can legally drive with a BAC of .4
Discretion is a bad thing. It's arbitrary and leads to abuse and uneven enforcement.
The perfect standard would allow both motorists and law enforcement to know where the line is. For motorists preferably before they have committed a crime.
BAC sucks. Driving while tired is just as dangerous. Objective measurements of reaction time and judgement are problematic because some drivers will fail just because.
I can't imagine the air sensors working very well. Can it pin point which person is the source of what ever it sniffed? What happens when the driver is the DD to her four drunk friends? I would think the four drunks would set those sensors off pretty quick. Does the car know who is drunk?