Emanation
Part of speech: noun
Definition: The act of flowing or proceeding from a fountain head or origin. That which issues, flows, or proceeds from any object as a source; efflux; an effluence; as, perfume is an emanation from a flower. radon
Emission
Part of speech: noun
Definition: Something that is emitted, especially the exhaust from a car.The act of sending or throwing out; the act of sending forth or putting into circulation; issue; as, the emission of light from the sun; the emission of heat from a fire; the issuing of bank notes.That which is sent out, issued, or put in circulation at one time; issue; as, the emission was mostly blood. Emission theory (Physics), the theory of Newton, regarding light as consisting of emitted particles or corpuscles. See Corpuscular theory, under Corpuscular.
Example sentence: Approximately 80% of our air pollution stems from hydrocarbons released by vegetation, so let's not go overboard in setting and enforcing tough emission standards from man-made sources.