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Blog/Opinion: Removing VOCs Using Plants and Biotechnology

I am pleased to see that HHI and AAFA will be helping Americans with allergies and asthma. It is my belief, as well as that of many other physicians and scientists, that airborne contaminants in the indoor environment play a significant role in the alarming increase of respiratory illnesses, particularly allergies and asthma.


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In a 1973 Skylab III mission, NASA detected more than 300 volatile organic chemicals (VOCs) inside the spacecraft. NASA soon realized that a tightly-sealed structure comprised primarily of synthetic materials, whether in space or on earth, could likely encounter serious indoor air quality (IAQ) issues.

To address these issues, we began to evaluate in sealed test chambers a variety of interior plants for their ability to remove VOCs commonly found in the indoor environment. NASA first published its findings in 1984. This discovery has drawn worldwide interest from news outlets and the general public and it continues to this day.

For further evaluation, NASA had constructed a tightly-sealed structure (approx. 640 ft2) termed ‘the Biohome.’ Comprised of synthetic materials, the Biohome was the typical ‘sick building.’ Mass Spec/GC analyses revealed high airborne levels of VOCs. Upon entering the facility, everyone experienced respiratory discomforts, including burning eyes and throat, breathing difficulties, etc. The Biohome was then equipped with a number of interior plants and an experimental fan-assisted planter. The planter’s substrate consisted of a soil/activated carbon mixture. Test data showed the planter as having the VOC-removal capacity of fifteen regularly potted plants. Analyses several days later proved that most all VOCs were removed. A student then lived in the Biohome for the summer and experienced no respiratory discomfort. Our studies were the first use of interior plants to remove VOCs from a tightly-sealed, non-ventilated structure.

These early studies have led to continued research efforts by scientists throughout the world and these efforts are ongoing. As a result, we now have a much greater understanding of biotechnology’s capabilities and limitations. For instance, we are now aware that the introduction of outside air in highly ventilated buildings will overwhelm a biological air filtration system, as is the case with mechanical filtration. Biological systems are much more effective in non-ventilated buildings.

Two opinions often cited in negative reviews of biological air filtration systems are those expressed by John Girman (EPA – Indoor Air Quality Program) and Hal Levin (Building Ecology Research Group, Santa Cruse, CA). They repeatedly cite one failed study (I did not participate in this study) of a highly-ventilated building where plants did not reduce VOCs. However, they fail to mention that due to high ventilation rates, indoor VOCs were roughly equivalent to those outdoors. However, as we all know, ventilation has not solved our IAQ issues, but does effectively reduce energy-efficiency and thereby increases energy costs.

The building industry and regulatory agencies continue to send mixed messages to the general public. Two articles in the same issue of Indoor Environment Connection (Jan. 2010; Vol. II; Issue 3), a newspaper for the IAQ industry, make my point. In one article, President Obama is promoting his ‘Cash for Caulkers’ program which encourages the public to seal all leaks to prevent outside air from leaking into homes, making them more energy-efficient and reducing energy costs. The second article is entitled, ‘California Study Finds Excessive Formaldehyde Levels.’ The study by the California Air Resources Board concluded that indoor concentrations of formaldehyde, benzene, naphthalene and 1,4-dichlorobenzene in recently built homes all exceeded exposure guidelines. The Board’s solution is to require all new homes in California to make use of mechanical ventilation. Where is the common sense in tightly sealing our homes, while simultaneously providing mechanical ventilation? Is it environmentally responsible to purge VOCs into the outdoor environment where the neighbor’s ventilation system might introduce the VOCs into their home?

In conclusion: (1) Research by many scientists have proven the validity of biological air filtration systems. No, just placing a few plants inside a building will not solve a serious IAQ problem, but neither will ventilation. (2) Studies show plants and plant-based air filtration systems to be far more effective in non-ventilated buildings. (3) The efficiency of fan-assisted planters have been improved ten-fold in their VOC removal capacity and are now commercially available ( (4) Studies also show that plants grown in hydroculture are more effective in removing VOCs than soil-grown plants, primarily due to increased air flow to root microbes. Hydroculture also has many other added benefits, such as reducing the incidence of mold and mildew as the surface remains dry. (5) Regulatory agencies in other countries have been far more supportive in funding research than in the U.S. As a result, the U.S. now lags far behind in incorporating biological air filtration systems into its air quality standards and in its implementation of viable demonstration projects.


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Removing VOCs Using Plants and Biotechnology:  Created on September 22nd, 2011.  Last Modified on November 6th, 2011

About B.C. Wolverton

B.C. "Bill" Wolverton is the founder of Wolverton Environmental Services, Inc. (WES), an environmental consulting firm providing services in the field of phytoremediation. Founded in 1990, WES advocates the use of plants and microorganisms to biodegrade and treat indoor air and water pollution.

Before WES, Dr. Wolverton conducted more than 30 years of research as a civilian scientist with the U.S. military and as a Senior Research Scientist with the National Aeronautics and Space Administration (NASA). His military research was directed toward developing means to protect against and destroy toxic chemicals and pathogenic microbes. Dr. Wolverton's NASA research was directed toward the development of a closed ecological life support system for long-term space habitation. Upon retirement from NASA, he has conducted research with plants and microorganisms toward solving earthly environmental pollution problems. Not only is he a world-renowned pioneer in the field of phytoremediation, but he has many years of practical application, primarily in wastewater treatment and indoor air pollution abatement.


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