Plants are often placed indoors for their visual appeal, but their ability to clean the air is another bonus.

Trees That Filter Room Air

by Cynthia Domenghini

Pollutants are found in many common household items. Formaldehyde is released into the air from various materials such as furniture made of pressboard, new carpet, cleaning products and permanent press fabrics, according to the EPA. Benzene and trichloroethylene are two other pollutants commonly found in homes. While all plants may have air-filtering qualities, some are better than others at breaking down pollutants.

1. Healthy Plants, Healthy Air

Newer homes tend to be better insulated to for energy conservation purposes, but this airtight quality traps the pollutants inside. While ventilation is important, plants can help. NASA recommends using houseplants to break down pollutants. To improve the air quality in an 1800-square-foot home, NASA recommends growing 15 houseplants, if each has the diameter of about 6 to 8 inches. Plants have small openings on the leaves called stomata that allow pollutants to enter into the plant. Pollutants are moved through the plant down to the roots and released into the soil where the microbes can break them down. Houseplants that do well in low-light, used in conjunction with activated carbon air filters, decrease pollutants in the air, including benzene, trichloroethylene, and formaldehyde, according to a 1989 report from NASA and the Association of Landscape Contractors of America: "Interior Plants for Indoor Air Pollution." Trees that can be grown as houseplants and that are included in the plants the NASA and ALCA report recommends includes varieties that have since been recommended by varying agencies, including the University of Illinois Extension, which organizes them by the type of pollutants they are best at reducing.

2. Ficus Trees

Among the best plants for cleaning the air in a home is the weeping fig (Ficus benjamina), which also adds beauty with its dark, glossy green leaves that are oval-shaped. The light gray trunk provides a nice color contrast. This tree will grow indefinitely tall if not restricted by space or pruning. Rubber plant (Ficus elastica "Robusta"), another top air freshening plant, also has dark colored leaves; however, the new leaves emerge reddish in color. Leaves are thick and can be up to 18 inches long. Depending on space, rubber plant can grow 6 to 10 feet tall. Outdoors, rubber plant and weeping fig thrives in U.S. Department of Agriculture plant hardiness zones 10 through 11.

3. Palms

Three of the palm trees studied by NASA that improve air quality: Areca palm (Chrysalidocarpus lutescens) has green feather-like fronds with light green stalks. The stems clump at the base of the plant and then can extend 10 to 20 feet high. Bamboo palm (Chamaedorea seifrizii) has 10 to 12 leaflets grouped together atop stalks. The leaves are a light green color. Stalks resemble bamboo and are clustered growing up to 12 feet tall. Dwarf date palm (Phoenix roebelenii) requires more space because of the wider growth habit. It can reach 10 feet tall with an equal spread. The fronds form an arch and are dark green. All three of these palms can be grown outdoors in USDA zones 10 through 11.

4. Dracaena and Philodendron

Not only an air-cleaner, but an intriguing plant, is lacy-tree philodendron (Philodendron bipinnatifidum) with its dark green, deeply lobed, two-foot long leaves. This tree can reach 10 to 15 feet tall if space is sufficient, and grows outdoors in USDA zones 9 through 11. A popular houseplant and air purifier, the red-edge dracaena (Dracaena marginata) can grow 15 to 20 feet tall. There are multiple cane-like stems that support thin, pointed leaves. Lacy-tree philodendron and red-edge dracaena thrive outdoors in USDA zones 10 through 11.

About the Author

Cynthia Domenghini holds a Ph.D. and bachelor's degree in horticulture, as well as a master's degree in teaching. She spent several years researching health outcomes of school gardening and has written numerous youth garden curricula and activity guides. Domenghini also served as an education specialist for the National Gardening Association.

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