NASA and the Associated Landscape Contractors of America's "Clean Air Study" concludes that indoor plants provides a natural way of removing toxic agents from the air and thereby neutralizing the effects of sick building syndrome. Indoor plants not only produce oxygen but can also absorb contaminants such as benzene and formaldehyde (known carcinogen), and trichloroethylene. NASA researchers suggest one plant per 100 square feet of home or office space can provide efficient air cleaning.
Plants can "filter" a room reducing 50-60 % airborne microbes (such as mold spores and bacteria), according to Dr. B.C. Wolverton's research at the Environmental Research Laboratory at John C. Stennis Space Centre. By absorbing pollutants into their leaves and emitting clean oxygen, interior plants can cut down on the expenses associated with illness.
A study conducted by Dr. Virginia Lohr of Washing State University found that participants were less stressed when plants were present.
A study carried out by Peter Costa of South Bank University (London, England) found that plants absorb background noise inside buildings.
Naturally controlling humidity levels, plants release moisture through transpiration. This can help contribute towards the human comfort range of 30 to 60 percent.