NASA Spinoff

Plants Clean Air and Water for Indoor Environments

Although one of NASA’s goals is to send people to the far reaches of our universe, it is still well known that people need Earth. We understand that humankind’s existence relies on its complex relationship with this planet’s environment—in particular, the regenerative qualities of Earth’s ecosystems.

In the late 1960s, B.C. “Bill” Wolverton was an environmental scientist working with the U.S. military to clean up the environmental messes left by biological warfare centers. At a test center in Florida, he was heading a facility that discovered that swamp plants were actually eliminating Agent Orange, which had entered the local waters through government testing near Eglin Air Force Base. After this success, he wanted to continue this line of research and moved to what was at the time called the Mississippi Test Facility, but is now known as NASA’s Stennis Space Center.

He was funded by the Space Agency to research the environment’s natural abilities to clean itself as part of what is now Stennis’ Environmental Assurance Program. The goals were to clean the Center of chemicals left behind through wastes and to supply information to NASA engineers about closed-environment “eco” support that may prove helpful in designing sustainable living environments for long-term habitation of space. A tertiary goal was to provide usable technologies to NASA’s Technology Utilization Program, essentially making the research available to the American public.

The first step for Wolverton’s research was to continue the remediation work he had started with the military. He was tasked with using plants to clean waste water at the NASA Center. To this day, Wolverton’s design, which replaces a traditional septic system with water hyacinths, is still in use. His research then turned to using plants to improve air quality.

In 1973, NASA scientists identified 107 volatile organic compounds (VOCs) in the air inside the Skylab space station. Synthetic materials, like those used to construct Skylab, give off low levels of chemicals. This effect, known as off-gassing, spreads the VOCs, such as formaldehyde, benzene, and trichloroethylene, all known irritants and potential carcinogens. When these chemicals are trapped without circulation, as was the case with the Skylab, the inhabitants may become ill, as the air they breathe is not given the natural scrubbing by Earth’s complex ecosystem.

Around the same time that Wolverton was conducting his research into VOCs, the United States found itself in an energy crisis. In response, builders began making houses and offices more energy efficient. One of the best ways to do this was to make the buildings as airtight as possible. While keeping temperature-controlled air in place, this approach reduced circulation. Combined with the modern use of synthetic materials, this contributed to what became known as Sick Building Syndrome, where toxins found in synthetic materials become concentrated inside sealed buildings, making people feel sick.

The solution Wolverton sought was not to make indoor environments less energy efficient or to move away from the convenience of synthetic materials; rather, the plan was to find a solution that restores personal environments. The answer, according to a NASA report later published by Wolverton in 1989, is that “If man is to move into closed environments, on Earth or in space, he must take along nature’s life support system.” Plants.

One of the NASA experiments testing this solution was the BioHome, an early experiment in what the Agency called “closed ecological life support systems.” The BioHome, a tightly sealed building constructed entirely of synthetic materials, was designed as suitable for one person to live in, with a great deal of the interior occupied by houseplants. Before the houseplants were added, though, anyone entering the newly constructed facility would experience burning eyes and respiratory difficulties, two of the most common symptoms of Sick Building Syndrome. Once the plants were introduced to the environment, analysis of the air quality indicated that most of the VOCs had been removed, and the symptoms disappeared.