Occupational Health & Safety

Plants: Elementary Answer to a Larger Problem

• By Pamela Kelly
• Feb 01, 2005

One expert says plants are especially needed in office buildings in which Sick Building Syndrome is common.

ALL of us have known since grade school that plants clean the air we breathe. And yet, the Environmental Protection Agency rates indoor air pollution among the world's top environmental health risks. With average Americans spending 90 percent of their time indoors and many facilities unable to afford and maintain a system to control humidity and/or being forced to operate contaminated systems, Sick Building Syndrome has been on the rise.

Sick Building Syndrome develops into a serious and expensive liability when toxins found in fibers (carpet, fabric, wall coverings) and solvents (wallboard, paints, varnishes, furniture) become concentrated inside sealed office buildings. The result is a notable increase in employee illness (generally, these are eye, lung, and upper respiratory problems, as well as allergies, colds, and viruses).

The National Aeronautics and Space Administration in Washington, D.C., reports the syndrome is widespread in energy-efficient buildings. The problem is that these sealed buildings have less exchange of fresh outdoor air for stale indoor air. This causes higher concentrations of toxic chemicals in indoor environments, brought about by emissions from a great variety of building constituents. Their data confirm that energy-efficient, sealed office structures are often 10 times more polluted than the air outside.

The answer to the problem is elementary, one we have known all along but have failed to implement until recently. Could it be as simple as plants?

Research shows plant-filled rooms contain 50-60 percent fewer airborne molds and bacteria than rooms without plants. For almost 20 years, Dr. Billy C. Wolverton and his aides in the Environmental Research Laboratory of the John C. Stennis Space Center (Picayune, Miss.) have been conducting innovative research employing natural biological processes for air purification. "We've found that plants can suck these chemicals out of the air," he said. "After some study, we've unraveled the mystery of how plants can act as the lungs and kidneys of these buildings."

The plants clean contaminated office air in two ways. They absorb office pollutants into their leaves and transmit the toxins to their roots, where they are transformed into a source of food for the plant. In his book "How to Grow Fresh Air: 50 Houseplants That Purify Your Home or Office" (Penguin, 1997), Wolverton details exactly how plants emit water vapors that create a pumping action to pull dirty air down around the roots, where it is once again converted into food for the plant.

Wolverton has found plants are especially needed in office buildings in which Sick Building Syndrome is common. He goes so far as to suggest that everyone should have a plant on his or her desk, within what he calls the "personal breathing zone." This is an area of six to eight cubic feet where you spend most of your working day. Jon Naar, author of "Design for A Livable Planet: How You Can Help Clean Up the Environment" (Harper & Row, 1990), suggests 15 to 20 plants are enough to clean the air in a 1,500-square-foot area.

Tove Fjeld, a professor at the Agricultural University in Oslo, Norway, conducted a two-year study in an office and found the following reductions in ailments after plants were introduced:

This article originally appeared in the February 2005 issue of Occupational Health & Safety.

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