Plants "Clean" Air Inside Our Homes

By Laura Pottorff, Cooperative Extension agent, horticulture, plant pathology

Houseplants are the latest word in household cleaning.
Research now shows that houseplants play an important role in cleaning the air we breath, both indoors and out.

Plants produce their own food through a process called photosynthesis. This means they take in carbon dioxide from the atmosphere and release oxygen. Photosynthesis "cleans" our air by absorbing carbon dioxide and by taking in certain other pollutants, as well.

A team of National Aeronautics and Space Administration (NASA) researchers lead by Dr. Bill Wolverton tested the effect of fifteen house plants on three pollutants known to be present in spacecrafts. These same three pollutants--benzene, formaldehyde and trichloroethylene--are present in homes and office buildings. They occur because they are emitted from furnishings, office equipment and some building materials. 

Under controlled conditions, in the NASA study, certain houseplants were found to remove as much as 87 percent of indoor air pollutants within 24 hours.

Until recently, indoor air pollution was not considered a health threat; most homes and public buildings leaked so much that air often was replaced every couple of hours. But during the 1970's, after energy shortages occurred, more and more of us began to insulate our houses and office buildings to conserve energy and lower heating and cooling costs. As a result, indoor air might linger for five hours or more allowing pollutants to accumulate.

Researchers are just beginning to understand how indoor pollutants such as cigarette smoke, for example, can harm humans. Effects range from skin and eye irritations to headaches and allergies. Some of the pollutants may be carcinogenic. According to the NASA study, the plants listed below proved effective in removing certain indoor air pollutants.

Troubleshooting Pollutants with Plants

Pollutant: Benzene
Source: Inks, oils, paints, plastics, rubber, dyes, detergents,gasoline, pharmaceutical, tobacco smoke, synthetic fibers
Plants that Remove Pollutant: English Ivy, Dracaena marginata, Janet Craig, Warneckei, Chrysanthemum, Gerbera Daisy, Peace lily


Pollutant: Trichloroethylene
Source: Primarily used in the metal degreasing and dry cleaning industries; also in printing inks, paints, lacquers, varnishes, adhesives
Plants that Remove Pollutant: Gerbera Daisy, Chrysanthemum, Peace lily, Warneckei, Dracaena marginata

Pollutant: Formaldehyde
Source: Foam insulation, plywood, pressed-wood products, grocery bags, waxed paper, fire retardants, adhesive binders in floor coverings, cigarette smoke, natural gas
Plants that Remove Pollutant: Azalea, Philodendron, Spider plant, Golden Pothos, Bamboo palm, Corn plant, Chrysanthemum, Mother-in-law's tongue


The NASA researchers suggest that for the test plants to be effective "air cleaners" it is necessary to use 1 potted plant per 100 square feet of home or office space. Indeed, it would appear that plants have many useful qualities, including one of making our indoor air cleaner to breath.*

*Information obtained from The Foliage For Clean Air Council and National Academy of Sciences.

Colorado State University & Denver County Extension Master Gardener. 2010.