A breath alcohol test (BAT) is an estimate of blood alcohol concentration (BAC). The test measures the amount of alcohol in the air that exhaled. The testing procedures for DOT breath alcohol testing are outlined in 49 CFR Part 40. They are very specific and must be followed whenever a DOT-required alcohol test is requested by the employer. These procedures include using a Federal Alcohol Testing Form (ATF) and applies only to DOT-required testing.