You smoked almost every day 4 many yrs then stopped 4 2 months and you smoked about a month ago once how long will it be in your system?

I smoked tobacco for 12 years and quit in 01/1979.
5 years later I got acute bronchitis and coughed
up flem with black specs in it from tobacco.

So it takes at least 5 years.

Most doctors say seven years, but no one really knows. One thing you'll know is that every day you are off cigarettes your lungs are getting clearer. Don't be too hard on yourself about the one cigarette, but that's a warning sign you are in a bad hump right now so see your doctor and ask for the patch to help you over the few bad times you may have. It isn't worth going back to smoking. Good luck