Using Mouthwash to Hide Liquor Breath
Before the advent of the roadside screening device the use of mouthwash to hide the odour of liquor on a driver's breath was not unheard of. Today using a mouthwash containing alcohol as you approach a road check can be a very dangerous thing to do. The alcohol present in your mouth from the mouthwash could produce a warn or fail reading on the device when your true blood alcohol level is less.
This topic was prompted by a woman who e-mailed me to present her husband's drinking history from the previous evening. After a good night's sleep, breakfast, tooth brushing and gargling with mouthwash he was checked by police on his way to work. The officer smelled liquor, tested the husband with a screening device and received a warn reading. She was concerned that having been tested within 10 minutes of gargling the warn reading was a result of mouth alcohol rather than breath alcohol from the previous evening.
There is some possibility that mouth alcohol did play a part in this situation. The exact scenario was played out when I taught other officers to use the screening device. The student partners each took turns rinsing their mouths with mouthwash and then testing to see how long it took for the mouth alcohol to dissipate. One partner was to talk after rinsing and the other was to keep their mouth closed except when providing a sample. In either case, after 10 minutes mouth alcohol no longer produced a reading.
I was somewhat suspicious of the scenario. Six drinks the evening previous, tooth brushing and mouthwash use prior to driving and the officer still smelled the odour of liquor on the driver's breath. Should this driver have consumed a significant amount of liquor during the evening it is possible that his blood alcohol level would be high enough to produce a warn the following morning without help from the mouthwash.