Living Wall at the University of Guelph-Humber.

University of Guelph-Humber in Toronto has a unique air-purification system: a 4-story tall wall of plants with about 1,000 plants that act as a biofilter.

... while the lush array that includes orchids, ferns, ivy and hibiscus is impressive, the truly innovative part of the biofilter - which has been operating for less than a year - is its capacity to break down hundreds of different kinds of contaminants found in indoor air.

Thanks to the action of microbes that live on the plant roots, common pollutants such as formaldehyde, toluene and benzene are transformed into harmless water and carbon dioxide. While the plants themselves have little impact on contaminants, they provide the environment for the microbes to work efficiently.

Link: Business Edge News | Guelph