With
 plants and trees being known for their ability to absorb and transform 
harmful gases like carbon dioxide, researchers at the US National Center
 for Atmospheric Research (NCAR) recently discovered other substances 
that plants also absorb. 
They found that some are particularly 
efficient at transforming chemicals known as oxygenated volatile organic
 compounds (oVOCs), which can create long term health and environmental 
damage, including contributing to lung infections and asthma attacks. 
Deciduous
 trees,which shed their leaves annually, were found to take in these 
chemicals four times faster than previously thought, with trees that are
 gathered in a forest setting being even more efficient.  
National 
Center for Atmospheric Research scientists, we appreciate these insights
 into the further gifts offered by the plant kingdom for human benefit. 
May our deeper appreciation inspire ever more protection for the natural world.  
http://www.treehugger.com/files/2010/10/plants-clean-up-more-air-pollution-than-previously-thought.php