Alcohol testing is done using DOT approved instruments called EBTs or "Evidential Breath Testing devices." EBTs test the content of deep lung air to determine if alcohol has been used recently.
In addition to the EBT devices, the government allows for the user of initial screening devices to test for alcohol. Some of these devices are saliva tests and simple breath tubes. The saliva tests as well as the breath tubes measure the alcohol content in the donor's saliva. The breath tube is a simple device that the donor breaths into and the results can be read within two minutes. A color change indicates the use of alcohol.