Trees and other vegetation must use what is in their environment. So it is not surprising to find that they absorb pollutants (natural or man made) which may be absorbed successfully or may cause the vegetation to die. Vegetation plays an unexpectedly large role in cleansing the atmosphere, a new study finds. The research, led by scientists at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., uses observations, gene expression studies, and computer modeling to show that deciduous plants absorb about a third more of a common class of air-polluting chemicals than previously thought.