EcoEng Newsletter No. 8, December 2003


Plants and the "sick building syndrome"

Interior plants make it possible to have an energy-efficient building without "Sick Building Syndrome," providing bottom-line savings on mounting sick leave expenses


By M.J. Gilhooley and Chris Rice, Plants at Work
Cincinatti & Los Angeles, USA

Press Contact:
M.J. Gilhooley, Director of Media Relations
Phone: +1-800-347-9014
Fax: +1-818-920-5522


Indoor air pollution is a health risk


The Environmental Protection Agency rates indoor air pollution among the world's top environmental health risks, since most Americans spend 90% of their time indoors. Many facilities can't afford to maintain a system to control humidity and/or are forced to operate contaminated systems, which emit disease-causing microorganisms. The result is a notable increase in employee illness. The most common illnesses are eye, lung and upper respiratory problems as well as allergies, colds and viruses. In addition, employee health and productivity are at risk due to common but dangerous office toxins found in fibers (carpet, fabric, wall coverings) and solvents (wallboard, paints, varnishes, furniture). Specifically, formaldehyde is found in office foam insulation, plywood, particleboard in desks and bookshelves, carpeting, paper goods, and janitorial supplies. Benzene is in offices rich with synthetic fibers, inks, plastics and tobacco smoke. Trichloroethylene comes from adhesives, inks, paints, lacquers and varnishes used in office buildings. 

Sick Building Syndrome develops into a serious and expensive liability when these toxins become concentrated inside sealed office buildings. The National Aeronautics and Space Administration (NASA, Washington, DC) reports that 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. As energy-efficient construction becomes absolutely essential, green building designers have become justifiably concerned about this indoor air quality dilemma. One of the most troubling reports comes from research published by Bio-Safe Incorporated (New Braunfels, Texas). Their data confirms that energy-efficient, sealed office structures are often 10 times more polluted than the air outside!


Indoor air pollution is expensive


According to studies done by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO), absenteeism related to poor indoor air quality has been on an alarming upswing. In recent studies, 40% of absenteeism was attributed to poor indoor air quality. Similarly, the same report demonstrates an increase of Worker Compensation Claims from 1980 to 1994 for indoor air quality issues. The number of such cases rose by almost 5,000 claims within that period and has continued to rise over the past few years. Many of these more recent cases have actually become litigants. The average cost of one of these Worker's Compensation Claims is US$27,850. The cost breakdown is US$4,750 in insurance premium increases, US$2,100 in human research costs and US$21,000 in medical treatment costs. What these figures do not account for is the cost to business for absenteeism of these individuals. If the absent worker happens to be in a supervisory or managerial position, there is a cascade effect on productivity losses from the staff they supervise.

Research shows that plant-filled rooms contain 50% to 60% fewer airborne molds and bacteria than rooms without plants. For almost 20 years, Dr. Billy C. Wolverton and his aids in the Environmental Research Laboratory of 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 says. "After some study, we've unraveled the mystery of how plants can act as the lungs and kidneys of these buildings." The plants absorb office pollutants into their leaves and transmit the toxins to their roots, where they are transformed into a source of food. In his book, How to Grow Fresh Air: 50 Houseplants That Purify Your Home or Office (Penguin, 1997), Dr. 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 that plants are especially needed in office buildings in which Sick Building Syndrome is common. He goes so far as to suggest that everyone 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 that 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 which found the following reductions in ailments after plants were introduced:







Sore/dry throats




Dry facial skin



At the International Plants for People Symposium, Fjeld presented his findings from another study with plants at the Radium Hospital in Oslo, Norway. After adding plants and full-spectrum lighting to their workspace, the absenteeism level among hospital workers reduced from 15% to just 5.6%, and stayed that way over five years.

Mr. Ron Wood at University of Technology, Sydney, Australia, also presented findings at the Symposium, where he stated, "When we remember that indoor air is often more polluted than outdoor air, having plants in our homes and workplaces becomes very important." Wood continued, "Plants clean, plant-shaped ornaments pollute."

If such a large body of credible research didn't exist, it would be hard to believe that a solution as simple and economical as indoor plants can address a problem as menacing and expensive as poor indoor air quality.

Plants at Work is a national educational campaign dedicated to informing professionals

and the public about the many benefits interior plants can bring to the workplace. For more information on these benefits, please see, or contact M.J. Gilhooley at


© 2003, International Ecological Engineering Society, Wolhusen, Switzerland