Why you smell cigarette smoke when there is none (meaning there’s no real smoke or other obvious source) may be due to a type of olfactory hallucination. In most cases, it happens during common respiratory infections like a cold or the flu.
Sometimes this sudden cigarette-smoke smell can be linked to other health conditions. Examples include head trauma, epilepsy, migraines, or psychiatric disorders.
For this reason, if you suddenly notice a smell of cigarette smoke, it’s best to consult a neurologist or your primary care provider, especially if these phantom odors occur often or are accompanied by other symptoms.