Smell of Smoke Caused by Sinus Infection?

For two months, I've been smelling cigarette smoke at work, at home, even in my car. I know there is no actual smoke in the air (I don't smoke and neither do my family or coworkers) but I smell it. I read that it could be a sinus problem or brain tumor.

Generally sinus disease or infection causes a foul odor and not the smell of cigarettes. Often odors can linger on clothing, carpet, furniture, automobile seats, drapery etc.

Some brain tumors can cause olfactory (smell) delusions or hallucinations and these can be manifest as almost any odor. Having said that, they are extremely rare.

If the odor is still perceived away from likely offending environments I would recommend seeing an otolaryngologist (ENT physician) for evaluation.