Cigarette smoke is a collection of over 4,000 chemicals. Nicotine is a deadly poison. Taken in high doses, it can kill. At one time, nicotine was used as an insecticide.
Cigarette smoke contains cyanide, a deadly poison.
Cigarette smoke contains formaldehyde, a chemical used a preserve dead frogs for biology class. Cigarette smoke contains methanol, a wood alcohol. Taken in sufficient amounts, methanol can cause blindness. It is also used as an additive in or substitute for gasoline. Cigarette smoke contains acetone, which is the prime ingredient of fingernail polish remover.