When law enforcement officers suspect people of drinking and driving, they may ask them to submit to breath alcohol tests. Drivers’ performance on these tests may contribute to their arrests, as well as provide evidence of their alleged intoxication at trial. Therefore, it behooves people to understand how these tests work and the factors that may affect their results. 

Once consumed, alcohol enters the stomach and small intestine where it gets absorbed into the bloodstream. As the alcohol gets carried throughout the body in the blood, the body expels it through breathing, sweating and other processes. 

According to the U.S. National Library of Medicine, drivers’ BAC levels, or blood-alcohol content levels, refers to the amount of alcohol in their blood. Measuring the amount of alcohol in the air drivers exhale, breath alcohol tests reflect people’s BAC levels, and thus, their level of intoxication. The devices used for obtaining such measurements may be manual or electronic. 

According to WebMD.com, several factors may affect people’s breath alcohol test readings. The fuel cell-based testing units used by law enforcement offer the most accuracy. However, they may still have erroneous readings due to issues such as the need for recharging or recalibration. A low charge or inappropriate settings may result in glitches that cause these devices to give falsely high or low results. 

Factors to do with the drivers may also affect the accuracy of breath alcohol test results. For example, a driver who used mouthwash or another alcohol-containing product may lead to false high readings. Likewise, residual alcohol in a driver’s mouth from a drink taken within 15 minutes of the administration of the test may also affect breath test device readings.