Do smartphone breathalyzer apps really work?

By Eric Flack | April 24, 2015 at 3:27 PM EDT - Updated July 25 at 1:14 PM

Greg Pippen tested one of the breathalyzer apps. (Source: WAVE 3 News)

This is what one of the apps showed Greg blew. (Source: WAVE 3 News)

What happened when Greg blew into a police officer's official breathlyzer? (Source: WAVE 3 News)

LOUISVILLE, KY (WAVE) - It's Derby time. For many, that means it's time to drink and party. But after a night on the town how do you know if you're over the legal limit?

Smartphone breathalyzers claim to be able to show you when you've hit your legal limit. So we decided to put the leading brands to the test.

Inside the Highlands Taproom on Bardstown Road the alcohol was flowing.

Participant Jimmie Welch said she tries to drink responsibly.

"If you drink you should be able to know you're limit," Welch said. "You should be able to know if you're good enough to drive or not."

Like the cocktails our test subjects were having, the results were mixed.

"I'm worried about it," said Shay Dobozi. "This could tell me I'm a .02 and I could be way higher than that."

In fact, when Dobozi blew into our least expensive device, the $40 Breathometer, it barely registered. Her reading was .01.

"No, over that," Dobzi admitted. "Over that for sure."

Way over that as it turned out.

Off-duty police officer Tony Lehman gave Dobozi the same portable breathalyzer test many police use and she blew a .175 - more than twice the legal limit.

The Breathometer read closer with the rest of our group, but not much. All blew a .20 on the Breathometer. Their police readings: .119, .134 and .144.

"That's a big difference," Welch said.

Next on the testing block: the $100 Alcohoot, which proved to be a hoot when Tracy Sunley, a drug and alcohol counselor, read off the charts.

Her Alcohoot reading was .284 - more than three times the legal limit and nowhere close to accurate. At least not according to our police breathalyzer, which showed Sunley at .144 - about half of what Alcohoot said she was.

Still, that's obviously way over the legal limit. The Alcohoot results were a little closer for everyone else, but not much.

Dobozi blew a .23 on the Alcohoot and a .175 on the police breathalyzer. Welch blew a .154 on the Alcohoot and a .119 on the police breathalyzer. And the fourth member of our test group, Greg Pippen, blew a .164 on the Alcohoot and .134 on the police breathalyzer.

The final smartphone breathalyzer WAVE 3 News tested was BACTrack Mobile Plus, available for about $105.

Welch blew a .119 on the BACTrack, the exact same reading he got on the police breathalyzer. Sunley blew a .15 on the BACTrack, virtually the same on the police breathalyzer, a .144.

Our other two BACTrack readings were just slightly off. Dobozi blew a .15 on the BACTrack and a .175 on the police breathalyzer.

Pippen blew .116 on the BACTrack and a .134 on the police breathalyzer.

"The arrogant, ego side of me, yeah, I feel like I would be ok to get home," Pippen said.

But Lehman said field breathalyzers are only part of the assessment if you get pulled over. Officers can arrest you for failing balance and coordination tests as well.

"Some people can test well below .08 and be impaired driving," he said.

Which is the reason most police say no matter how accurate you think smartphone breathalyzers are, the safest thing to do is just not drive if you've been drinking. It's also the reason Yellow Cab of Louisville gave everyone involved in this test a free ride home.

"Breathometer said their devices are geared towards giving consumers a good baseline of whether alcohol affects them, not if they should get behind the wheel of a car. Breathometer also said it believes in the accuracy of their product and offered to exchange the unit we tested believing our results were not accurate. Here's the complete statement:

Thanks for taking the time to test our breathalyzer for your piece. Breathometer believes that our personal devices for testing BAC levels are geared towards giving consumers a good baseline of how the consumption of alcohol affects them – not if they should get behind the wheel of a car as alcohol effects everyone differently. At no time should anyone that has consumed alcohol consider operating a motor vehicle. Don't drink and drive.

Breathometer focuses on providing our customers with more than an estimated BAC level, starting with the Back to Zero information provided whenever alcohol is detected. This helps educate the user about the length of time it takes for alcohol to actually metabolize, or to return to being sober. We also feature Get Home Safe options, and Stay Nearby options, which provide local options to make better decisions.

Breathometer believes in the accuracy of our product with proper use and do not believe the results you had are reflective of the products. We would like to exchange the unit you utilized so we can confirm the settings and your findings."

BACtrack said it was pleased to see the Mobile Pro delivered results consistent with the police breathalyzer. Here's BACTrack's complete statement.

"It is great to see WAVE 3 News highlight the topic of alcohol consumption and breathalyzers. BACtrack is dedicated to providing the most accurate, reliable and affordable breathalyzers, and we're pleased to see BACtrack Mobile Pro delivered results consistent with the police breathalyzer. BACtrack is proud to offer an affordable way for consumers to estimate their alcohol level."

On May 6, WAVE 3 News received the following statement from Alcohoot:

"We are pleased that there is currently a larger conversation around personal alcohol limits and the dangers of over consumption. Whether the testing conditions were accurate or not - the study addresses the fact that using Alcohoot, or any personal breathalyzer, enhances the public's education around the effects of alcohol on the body.

Alcohoot stands behind the accuracy of our products and, under proper testing conditions, the results have proven to be as accurate as police-grade breathalyzer devices. However, in any situation, we do not promote anyone to solely rely on any personal breathalyzer device to make what ultimately could be a life or death decision."