How accurate are personal breathalyzers?

Charles Yim’s little smartphone invention called the Breathometer was enough to turn the heads of all “sharks” on ABC’s “Shark Tank” investment-themed reality television show last year.

His breathalyzer app for iPhones grabbed headlines, investors and a huge demand as a result of the exposure.

Skeptics, though, wondered just how reliable the little device was compared to breathalyzers police use.

"The police department uses an instrument that's calibrated weekly and it's controlled by the board of health with very strict rules on how this instrument is used,” Lt. Bruce Hofbauer, a commander with the Cincinnati Police Department's traffic section said. “It is very accurate, it's accepted by the courts.  Now this instrument, thing you would put on your phone, your app, is not something that's controlled.  So the accuracy is very much in question."

And though Hofbauer and his department couldn’t legally compare their breathalyzer results to those of products like the Breathometer, an officer agreed to go out with a WCPO reporter to give the popular products a road test.

Jon Kennedy of Cincinnati was leaving his favorite watering hole downtown when he was approached to try the Breathometer and another device currently on the market.

Kennedy said he had two beers before breathing into the Breathometer and second smartphone product selected by WCPO called the BACtrack . Kennedy blew 0.07 on Yim’s device. Moments later he blew .089 on the BACtrack.

"That's better than I expected," Jon said.

The difference between the BACtrack and the Breathometer was enough to determine whether or not a driver went to jail in Ohio or Kentucky, but within a reasonable range for an average adult male who slowly drank two beers.

Another volunteer who identified herself as Maude blew a  0.15 on the Breathometer and a 0.137 in Covington’s Mainstrasse Village.

“It’s why I called a taxi,” Maude said. "I mean I already knew that I wasn't well enough to drive. But I feel like a lot of people maybe wouldn't know.”

Both Maude and Jon said they could see an upside to a personal breathalyzer.

"I could see how it could be useful. Like, maybe somebody would blow into it and decide, oh I shouldn't drive," Jon said.

Lt. Hofbauer though warns drivers that if they are not careful, the little devices could work against them if someone like him eventually pulls them over.

"If they say, no I wasn't drinking and they refuse all of our tests, and they can do that, but then we would get a search warrant for that (smartphone app) and it shows you blew into your instrument on the phone."

Bottom line, Hofbauer said, don't count on an exact reading from a personal breathalyzer. The companies don't claim to be full proof and the fact is that drinking and driving don’t not mix.

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