What about breath tests and smoking? When you are stopped at the roadside for an impaired driving investigation, the police will often ask you to blow into a roadside breath testing device. These are known in law as Approved Screening Devices (ASDs). But what happens if you just finished a cigarette and you are asked to blow?
The ASD is fallible. It cannot distinguish between mouth alcohol and alcohol in the body. It is the responsibility of the police to ensure that they are using the ASD properly and are not using it in circumstances where the results could be contaminated by the presence of mouth alcohol.
I have been asked by many clients about the impact that smoking can have on the reliability of the ASD result. Should we be concerned about breath tests and smoking?
The RCMP are told to delay using the ASD for a few minutes if they know a person has been smoking recently. It is said that blowing smoke into the device can damage the ASD and it will give inaccurate readings.
However, the actual presence of smoke does not elevate blood alcohol readings. This issue has been studied. The British Medical Journal published a report in January 1991 about the effects of smoking on alcohol absorption. The authors examined individuals who consumed a meal with alcohol and measured the impact that smoking had on their gastric emptying and the rate at which they absorbed alcohol.They found that cigarette smoking actually slows gastric emptying and delays the absorption of alcohol into the blood.
The smoking issue is thus generally only relevant in cases where breath samples are taken outside the two-hour time limit and the police are required to rely on extrapolation to calculate the readings back to the time of driving. If the accused had been smoking, the readings at the time of driving may not have been as elevated as the calculations suggest.
There are other factors, however, that can impact the readings on the ASD. Chewing tobacco and gum can trap alcohol in the mouth and may contribute to an elevated reading. Police are required to delay taking an ASD sample for fifteen minutes where there is a risk that mouth alcohol may elevate the readings. Recent consumption of alcohol, as well as burping, belching, and vomiting, can also cause the presence of mouth alcohol.