In every AlcoHAWK manual we state that you should wait 20 minutes after smoking, eating or drinking before testing.
We also have a list of precautions in each manual, one of these precautions reads "Do not blow smoke, food or liquid into the unit." Why do we make such a big deal out of smoking before using your breathalyzer? Because we want you to get the longest life possible out of your breathalyzer. Failure to follow the instructions and precautions given in the manual can harm the sensor of your personal breathalyzer.
But, besides causing harm to the sensor itself (and your body) smoking can also affect your breathalyzer results because smoking causes a delay in alcohol absorption in your body. So if you're drinking and smoking and are using a breathalyzer to monitor your BAC you could end up drinking more than you wanted to. Not good.
So please, in the future if you smoke, wait 20 minutes before using your breathalyzer.
You want a more technical explination? You can find an article1 about the study in the highly respected British Medical Journal.
1 British Medical Journal; Cigarette smoking and rate of gastric emptying: effect on alcohol absorption
Leave a comment if you please.