Cigarette residue is composed of two main components: TAR and ASH. TAR is a dark, viscous liquid that is produced when tobacco is burned and is the main component of cigarette smoke. It is composed of many chemicals, including nicotine, carbon monoxide, and polycyclic aromatic hydrocarbons. ASH is the solid material that remains after the combustion of tobacco and is composed of minerals and other compounds. Both TAR and ASH are hazardous to human health and can cause serious respiratory and cardiovascular diseases.