At room temperature, acrolein (also called propenal or acrylaldehyde) is a colourless or yellow liquid. Acrolein is produced when organic materials such as tobacco are burned incompletely. Under these circumstances acrolein is a gas and can be inhaled. It is a very reactive substance with an unpleasant, penetrating, pungent odour.

Acrolein is released in automobile exhaust fumes, as well as from factories where acrolein is used. Acrolein is also released when tobacco is smoked. Acrolein is used as a pesticide to fight algae, weeds, bacteria and molluscs. It is also used as a raw material for making other chemicals.

Acrolein in tobacco smoke

Acrolein is not added to tobacco. Rather, it is produced during smoking by the burning of sugars present in the tobacco. Smokers inhale it when they take a puff of smoke (first-hand smoke). It is also inhaled in smaller amounts by passive smokers (second-hand smoke).

Adverse health effects

Acrolein is a very reactive substance which can cause irritation even in low concentrations and with short exposure times. Because of its strong reactivity, the effects of acrolein occur at the place of initial contact. Exposure to acrolein from smoking (and passive smoking) can cause the airways to become irritated.