Volatile Organic Compounds (VOCs)
Volatile organic compounds are comprised of a wide range of individual substances including hydrocarbons (alkanes, alkenes, and aromatics), halocarbons (e.g. trichloroethylene), and oxygenates (alcohols, aldehydes, and hetons). They are all organic compounds and are volatile enough to exist as vapour in the atmosphere under normal conditions.
Sources of VOCs:
Hydrocarbons (HC) arise mainly from the incomplete combustion of fuels and petrol evaporation. Oxygenates originate from vehicle exhaust and are also formed through atmospheric chemical reactions. Hydrocarbons, oxygenates, and halocarbons are also released into the atmosphere through the evaporation of solvents such as those used in paints or industrial degreasing processes.
Human Health Effects of VOCs:
A number of VOCs are proven or suspected to cause cancer.
Environmental Effects of VOCs:
HCs contribute to the formation of secondary pollutants such as ground-level ozone, to the depletion of stratospheric ozone, and indirectly to the formation of atmospheric acidity.
Ethylene, a major VOC component, is a plant hormone and can seriously inhibit the growth of plants.