Why is there a 15-minute waiting period before administering a breath test?

The reasoning behind the 15-minute waiting period before administering a breath test is primarily to ensure that there is no mouth alcohol affecting the results. During this time, the individual being tested is observed to make certain that they do not consume any substances that could influence the test outcome. Mouth alcohol can arise from recent ingestion of alcoholic beverages or products that contain alcohol, such as mouthwash or breath fresheners.

If residual alcohol from the mouth interferes with the breath sample, it can produce a falsely elevated blood alcohol concentration (BAC) reading. The 15-minute observation period helps to eliminate the potential for such contamination by ensuring that the individual has not had any alcohol in their mouth for at least that duration. This is an essential step in maintaining the accuracy and reliability of the breath test results. Thus, this waiting period is a critical protocol in breath alcohol testing procedures.