It is an aromatic hydrocarbon occurs naturally at low levels in crude oil and is usually produced in the processes of making gasoline via catalytic reforming. It is a clear, water-insoluble liquid with the smell of paint thinner. The majority of ethyltoluene is used as a petrol constituent in the C9 fraction produced from petroleum refining, which also contains 1,2,4-trimethylbenzene and other trimethylbenzenes (see 1,2,4 trimethylbenzene). 2-Ethyltoluene is also a volatile organic compound VOC which can contribute to the formation of harmful ground level ozone formation. Releases of 2-ethyltoluene are directly to the air from fugitive emissions from petroleum refining, and car exhausts. As a VOC, 2-ethyltoluene can be involved in reactions with other air pollutants that can form ground-level ozone, which can damage crops and materials as well as having negative effects on human health.