Can plants clean the air in your home?

by Deborah Mitchell

Clean the air in your home with houseplants Houseplants are great for decoration, but they serve an even more important purpose. They help clean the air you breathe.

During the early 1970s, the National Aeronautics and Space Administration (NASA) discovered that the air inside Sky Lab 3 was contaminated with more than 100 toxic substances.

NASA needed a way to ensure clean air in its spacecraft. So they put environmental engineer Bill Wolverton, PhD, to the task. After much research, he found a simple, natural answer: plants.

Dr. Wolverton knew that plants recycle oxygen, so he placed different plants in sealed chambers into which he injected common indoor air pollutants, such as benzene, formaldehyde, and trichloroethylene, to see if the plants would break down the toxins. He didnt have to wait long. Within 24 hours, Boston fern, dracaena, Ficus benjamina (rubber plant), and chrysanthemum eliminated up to 90% of the poisons in the chambers.

Around the same time, Americans began making office buildings and homes more energy efficient. In many cases, windows in office and public buildings were designed to be permanently closed, and air systems were installed to filter and recirculate the air. In addition, builders began using more synthetic materials, which contain potentially toxic chemicals.

According to the Environmental Protection Agency (EPA), there are toxic substances lurking in the air in modern offices and homes. These substances, known as volatile organic compounds, are in building materials and furniture composed of or treated with synthetic materials. These toxins are emitted into the air by the materials and can cause symptoms such as headache, nausea, dizziness, heart palpitations, blurred vision, and eye and throat irritation. In addition, VOCs have been linked to multiple chemical sensitivity syndrome

Dozens of plants are effective at removing pollutants from indoor air. The plants absorb the chemicals through tiny holes in their leaves, and bacteria in the roots break down the pollutants, which are then used by the plant as food. Not only are plants excellent recyclers, but they also get better with time.

"The longer a plant is exposed to certain chemicals, the more effective it becomes at removing them," says Dr. Wolverton.

Below is a list of the most effective plants for removing common indoor air pollutants, such as formaldehyde, carbon monoxide, benzene, and trichloroethylene. Plants in the palm family are the best at removing volatile organic compounds from indoor air, according to Dr. Wolverton.

• Bamboo palm
• Chinese evergreen
• English ivy
• Chrysanthemum
• Corn plant (a type of Dracaena)
• Diffenbachia
• Mother-in-laws tongue
• Janet Craig (a type of Dracaena)
• Peace lily
• Marginata (a type of Dracaena)
• Spider plant
• Warneckii (a type of Dracaena)
• Golden pothos
• Wandering Jew
• Rubber plant

Two potted plants per 100 square feet of floor space will help clean and freshen the air in a home. Dr. Wolverton suggests placing a plant within your "personal breathing zone" a space six to eight cubic feet around where you work at your computer, watch television, or sleep. Placing several inches of aquarium gravel over the soil in the plant container will help prevent the formation of mold, a common allergen.

Although the experiments of Dr. Wolverton and other scientists indicate that plants can remove contaminants from indoor air, the EPA notes that most research to date has used only small chambers. Therefore, the results cannot necessarily be applied to large offices and entire homes. The EPA maintains that the ability of plants to improve indoor air quality is limited compared with the effectiveness of proper ventilation.