Definīcija:In air pollution control, the concentration of air pollutants in a definite area during a fixed period of time prior to the starting up or on the stoppage of a source of emission under control. In toxic substances monitoring, the average presence in the environment, originally referring to naturally occurring phenomena.
VVC izstrādātie vides zinātņu, zemes zinātņu un fiziskās ģeogrāfijas termini