An FTIR spectrometer equipped with a long-path gas cell can be used to measure breath alcohol concentrations in an instrumental analysis laboratory course. Students use aqueous ethanol solutions to make a calibration curve that relates absorbance signals of breath samples with blood alcohol concentrations. Students use their calibration curve to determine the time needed for their calculated blood alcohol levels to drop below the legal limit following use of a commercial mouthwash. They also calculate their blood alcohol levels immediately after chewing bread. The main goal of the experiment is to provide the students with an interesting laboratory exercise that teaches them about infrared spectrometers. While the results are meant to be only semiquantitative, they have compared well with results from other published studies. A reference is included that describes how to fabricate a long-path gas cell.