The study was conducted by Dr. B.C. Wolverton, Anne Johnson, and Keith Bounds in 1989. While it was originally intended to find ways to purify the air for extended stays in orbiting space stations, the study proved to have implications on Earth as well.

Newer homes and buildings, designed for energy efficiency, are often tightly sealed to avoid energy loss from heating and air conditioning systems. Moreover, synthetic building materials used in modern construction have been found to produce potential pollutants that remain trapped in these unventilated buildings.

The trapped pollutants result in what is often called the Sick Building Syndrome. With our ultra modern homes and offices that are virtually sealed off from the outside environment, this study is just as important now as when it was first published.

While it’s a well known fact that plants convert carbon dioxide into oxygen through photosynthesis, the NASA/ALCA study showed that many houseplants also remove harmful elements such as trichloroethylene, benzene, and formaldehyde from the air.

NASA and ALCA spent two years testing 19 different common houseplants  for their ability to remove these common pollutants from the air. Of the 19 plants they studied, 17 are considered true houseplants, and two, gerbera daisies and chrysanthemums, are more commonly used indoors as seasonal decorations.

The advantage that houseplants have over other plants is that they are adapted to tropical areas where they grow beneath dense tropical canopies and must survive in areas of low light. These plants are thus ultra-efficient at capturing light, which also means that they must be very efficient in processing the gasses necessary for photosynthesis. Because of this fact, they have greater potential to absorb other gases, including potentially harmful ones.

In the study NASA and ALCA tested primarily for three chemicals: Formaldehyde, Benzene, and Trichloroethylene. Formaldehyde is used in many building materials including particle board and foam insulations. Additionally, many cleaning products contain this chemical. Benzene is a common solvent found in oils and paints. Trichloroethylene is used in paints, adhesives, inks, and varnishes.”