This page is part of the Earth Journalism Toolkit’s glossary.

United Nations Environment Programme: The United Nations Environment Programme (UNEP), established in 1972, works to encourage sustainable development through sound environmental practices everywhere.

Urban heat island: the tendency for urban areas to have warmer air temperatures than the surrounding rural landscape, due to the low albedo of streets, sidewalks, parking lots, and buildings. These surfaces absorb solar radiation during the day and release it at night, resulting in higher night temperatures.

Vaccine: A vaccine is a biological preparation that improves immunity to a particular disease.

Vinyl: a type of plastic (usually PVC) used to make products such as fruit juice bottles, credit cards, pipes and hoses.

Virtual water: the volume of water required to produce a commodity or service – also known as embedded water

Virulence: A measure of how harmful a pathogen is.

Volatile: Evaporating readily at normal temperatures and pressures. The air concentration of a highly volatile chemical can increase quickly in a closed room.

Volatile organic compound (VOC): An organic chemical that evaporates readily. Petroleum products such as kerosene, gasoline and mineral spirits contain VOCs. Chlorinated solvents such as those used by dry cleaners or contained in paint strippers are also VOCs.