Kamal Meattle became allergic to ambient air, with his lung capacity going down to 70%. His research found that three plants were particularly good at cleaning and purifying air (see here for more info):
What he learned for his own health purposes, Meattle has applied in an old building in Delhi where people who stayed in the building were able to improve their oxygen levels, and were less susceptible to eye irritation, headaches, lung impairment and asthma. Meattle calculates the benefits in productivity of the people to be over 2o%, while reducing energy costs for air circulation and purification.
They are now building a 1.75M sq. ft. building according to these principles, which will incorporate 60,000 plants. The building is expected to be ready by 2011. You can learn more about this building at the GreenSpaces web site(click here).