Humectants are used in the manufacturing of some tobacco products, such as cigarettes, e-cigarettes, and self-rolled tobacco. They are used to control and maintain the moisture content of the cut tobacco filler and add flavor. Humectants are vital to the creation of cigarettes. In an examination of waterpipe smoking, researchers worked to identify substances such as formaldehyde, acetaldehyde, and acrolein in the smoke of a waterpipe, discovering that the value of formaldehyde detected in one smoking session was five times higher than that of a regular cigarette. This data demonstrated that increasing amounts of humectants in the unburned tobacco lowered the temperature in the waterpipe head during smoking, so that considerable amounts of toxic substances were present. Further, e-cigarettes produce aerosol by heating a humectant containing nicotine without burning tobacco. Those "vaping" then inhale the aerosol and receive nicotine.