Research Questions Accuracy of Smartphone Alcohol Breath Testers

May 10, 2021

Alcohol breath testing devices that pair with smartphones are marketed as safety tools for general use, but their accuracy is highly variable, a new laboratory study shows.

According to the report from the Research Society on Alcoholism, while some of these widely-available devices potentially help people avoid driving while impaired, others may mislead users into thinking falsely that they are fit to drive.

The study in Alcoholism: Clinical & Experimental Research compared the accuracy of six devices with that of two validated alcohol-consumption tests including a police-grade handheld device. Researchers worked with 20 moderate drinkers aged 21–39, testing their breath alcohol concentration (BrAC) several times after giving them doses of alcohol and then testing their blood alcohol concentration (BAC), which is the the most accurate way of measuring alcohol consumption.

The participants’ peak blood alcohol concentration ranged from 0.06% to 0.14%. All the breath-testing devices, including the police-grade device, underestimated BAC, consistent with previous research — in this study by a mean of more than 0.01%.

The accuracy of smartphone-paired devices varied widely. The most accurate — the BACtrack Mobile Pro and the police-grade device — underestimated BAC by no more than 0.02%.

Other devices yielded wider margins. Drinkmate and DRIVESAFE Evoc generated average estimates of 0.04% below peak BAC; BACtrack Vio and Floome differed significantly from the police-grade device at certain points in the study.

The devices also varied in detecting driving-limit thresholds. BACtrack Mobile Pro and Alcohoot were the most sensitive, while Drinkmate and DRIVESAFE failed to detect BAC limit thresholds of 0.08% more than half the time.

The researchers concluded that such devices are potentially useful for remotely monitoring alcohol consumption and may help reduce risky driving behavior. The BACtrack Mobile Pro, for example, was suitable for personal, clinical, and research use. Other devices, however, dangerously underestimated BAC and frequently failed to detect risky breath-alcohol levels, they concluded.

The researchers recommend closer government regulation of such devices and research into their effects on users’ decisions to drive.

Since the study was conducted, Drinkmate has been discontinued and some models have been updated.

Alcohol-impaired driving kills 29 people a day and costs $121 billion a year in the U.S, according to the research society.

Original Study: Accuracy of Consumer‐marketed smartphone‐paired alcohol breath testing devices: A laboratory validation study by M. Delgado, F. Shofer, R. Weatherill, B. Curtis, J. Hemmons, E. Spencer, C. Branas, D. Wiebe, H. Kranzler.

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