Section 67 Simulators Are Unlike Human Breath

• Library: DWI Experts and the Science of Chemical Tests 2014

Simulators contain pure ethanol and water (or pure gas), whereas human breath has many different components and many possible interferents. Alcohol vapor from the stomach escaping through the lower esophageal sphincter or trapped in the laryngeal cleft or laryngotracheoesophageal cleft in the throat can mix with exhaled breath in the mouth before being blown into the machine and cause a false breath alcohol.

The vapor/gas is pumped in the machine at a constant pressure, humidity, and temperature of 34°C +/- 0.2, not through the actual breath tube, but via a separate port...