Evidential Breath Testing Device

Definition - What does Evidential Breath Testing Device mean?

An evidential breath testing (EBT) device is a device that measures the alcohol level of a person through his breath. The concentration of alcohol in the breath is related to the concentration of alcohol in the blood so it is possible to calculate the alcohol levels through the use of this device. Specifically, evidential breath testing devices are those approved for DOT (Department of Transportation) testing and those that are generally accepted for legal proof in court. Devices that fall under the evidential breath testing device designation are determined by the National Highway Traffic Safety Administration (NHTSA) and listed in the Conforming Products List (CPL).

WorkplaceTesting explains Evidential Breath Testing Device

Evidential breath testing devices are all tested to the highest standards before getting approval from the DOT. Though they are mostly used by law enforcement officials, evidential breath testing devices are also sometimes used in the workplace when there is a reasonable suspicion, after an accident, randomly, and during pre-employment testing.


EBT devices use either an infrared cell or a fuel cell. In the case of infrared cells, the cells directs the infrared energy to the sample and the energy that does not get absorbed at the other side is detected by the device. If the concentration of ethanol is high, then there will be more absorption of infrared energy. Just like sunglasses are able to absorb light, alcohol is able to absorb infrared light.


An EBT must be able to:


  • Provide three copies of the result of each breath test
  • Assign a unique number to each successfully completed test
  • Print the name of the device along with its serial number and the time when the test was taken
  • Distinguish acetone from alcohol at a 0.02 alcohol concentration level
  • Test an air blank
  • Execute an external calibration check.
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