Xylene is a colorless, sweet-smelling gas. It is mostly a synthetic chemical that is produced from petrol. It also occurs naturally in petrol and coal tar and is formed during forest fires. Xylene is used as a solvent in the printing, rubber, and leather industries. It is also used as a cleaning agent, a thinner for paint, and in paints and varnishes. It is found in small amounts in airplane fuel and gasoline and small amounts are found in cigarette smoke.