A breath alcohol test roughly quantitates the alcohol content of the blood by measuring the alcohol content of exhaled air. The test can be performed after waiting at least 15 minutes since the last drink of an alcoholic beverage (at least 1 minute after smoking).

Breath alcohol testing can be done using either an electronic or manual meter. There are various brands of breath alcohol testers that use different methods to test the level of alcohol in the breath. Carefully read the instructions before using the test to assure accurate alcohol testing. The test helps you to know how much alcohol it takes to raise the blood-alcohol level to a dangerous level. Each person's response to alcohol varies. The test may help you make better decisions about driving after drinking

An example of a common tester requires you to inflate the balloon enclosed with the test in one continuous breath until it is full. Attach the balloon mouthpiece to one end of the glass tube. The tube is filled with bands of yellow crystals. Release the air slowly through the tube for 1 minute. Then count the bands in the tube that have changed from yellow to green. If an electronic alcohol meter is used, follow the instructions that come with the meter.