A screening test give preliminary test results. If the test result is negative, no further testing is required. If the screening test shows the presence of alcohol then a second test should be performed using an evidential quality device.
For DOT alcohol testing a positive test result is .020 or higher. However, for testing in any other application, the company or agency may choose their own policy for determining a positive test.
DOT alcohol testing uses a two-test procedure. The first of the two tests is called a screening test. Every employee requiring a test for alcohol under DOT regulations receives a screening test. If the screening test determines the subject has no alcohol present, or if the alcohol level is less than .020, the testing process ends with the screening test. If the screening test is .020 or higher, then the BAT performs a second test called the confirmation test.
Any alcohol testing device may be used to perform a screening test for non-regulated alcohol testing. Companies performing DOT alcohol testing must use either an Alcohol Screening Device (ASD) or an Evidential Breath Tester (EBT) to perform the screening test.