Volatile organic compounds (or VOC) include many substances that may be of a biogenic origin (natural origin) or anthropogenic origin (human origin). They are always composed of the element carbon and other elements such as hydrogen, halogens, oxygen and sulphur.
Their volatility permits them to move away from their place of emission, thus causing direct and indirect impacts on animals and nature. They are contained in solid materials and liquids used for industrial or everyday purposes. Some VOCs modify the chemical composition of the ambient air. In this case they are considered to be pollutants.
Here are a few examples of well-known VOCs: butane, propane, ethanol (90 alcohol), acetone, paint solvents and ink solvents.