Most ignition interlock devices operate on fuel cell technology. Fuel cell technology is alcohol-specific and isn't affected by outside interference. This means that there is little chance of your IID registering a false positive because of cigarette smoke, perfume, gasoline, etc. However, any amount of alcohol that is blown into an ignition interlock device will register. This means that if you use mouthwash with alcohol in it, eat liquor-filled candy, or even eat a pastry (sometimes the combination of sugar and active yeast produce low levels of alcohol), the IID will pick up on and register alcohol in your blood sample. The good news is that when alcohol registers, you will usually be given the opportunity to retest almost immediately.  The low levels of alcohol that may be present in these types of situations quickly disappear. Rinsing your mouth with water in between samples can help to expedite this process.