RVSM is a measure that has been implemented to reduce the vertical separation minima of aircraft flying between flight level 290 (29000 ft) and 410 (41000 ft).
This measure enhances the capacity of the airspace which might look as stimulation of the activities and of its consequent emissions. However, this measure also makes it possible to reduce the detours aircraft make to avoid each others vicinity and thus allow to reduce unnecessary emissions.
Since 1997 RVSM has been progressively implemented in large parts of the world (incl. Europe, North Africa, Southeast Asia, North America, Atlantic and Pacific Oceans).
=> Glossary