Updated: June 11, 2009, 12:03 pm

Going Green Indoors: Clear The Air With Houseplants

By Anne Halpin | 1 Comment

The plants absorb the chemicals through their leaves and move them down to the root system, where microbes break them down. Basically, the plants use the pollutants as food. Photos courtesy of Jupiter Images

Southampton - "Take a deep breath." It's good advice, most of the time. A good, deep breath is restorative. It can help calm you down, clear your head, prepare you for an important task.

Most of us don't think much about the air we breathe at home or at work. We take for granted that the air we inhale is safe, cooled and cleaned by air conditioners, heating systems and filters. But you might be surprised to learn that the U.S. Environmental Protection Agency now considers indoor air pollution to be one of the top five threats to human health. There's even a name for the problem - sick building syndrome. The EPA estimates there are 100 to 200 different contaminants (called volatile organic compounds - VOCs) in the air of the average home.

About 25 years ago, NASA researchers working on ways to maintain clean
air in spacecraft during extended missions discovered that plants are
effective air cleaners.

When enough of these compounds are present, people working or living in buildings can become ill, developing such symptoms as headaches, allergies, asthma, and eye and skin irritations.

Modern building materials, furnishings, and office equipment contain chemical compounds that escape into the air and accumulate over time. The best way to get rid of VOCs is to open the windows. When that's not feasible there are alternatives. Using all-natural building materials and furnishings prevents problems, too, but they're most useful for new construction. But there's a simple way to clean up the air in your indoor space - bring in some houseplants. Yes, plants. They've been found to clear toxins from the air indoors.

About 25 years ago, NASA researchers working on ways to maintain clean air in spacecraft during extended missions discovered that plants are effective air cleaners. Basic photosynthesis enables plants to absorb carbon dioxide and transpire oxygen back into the air, but they can also remove benzene, formaldehyde, and trichloroethylene, which are present in many homes and offices. The plants absorb the chemicals through their leaves and move them down to the root system, where microbes break them down. Basically, the plants use the pollutants as food.

If you live in an old, drafty house you probably don't have to worry much about toxins in your air. But if your house is tightly insulated, with central air and double-paned windows, it's time to bring in some houseplants. When it comes to air cleaning, not all houseplants are created equal. Luckily, some of the best ones to use are easy to grow and don't demand a sunny window.

Some of the best plants to grow? Bamboo palm, corn plant (a species of Dracaena, not edible corn), dragon tree, and golden pothos will thrive in a bright east or west-facing window. For a north window that gets no sun at all, try Chinese evergreen, English ivy, peace lily, philodendron, or snake plant. For best results, grow any of them in a good all-purpose potting mix, with some filtering charcoal (not barbecue briquettes) mixed in. If the plant's bottom leaves are close to the soil, trim them off so the soil is open to the air. Water the plants to keep the soil evenly moist, but not soggy, and feed them once a month with compost tea or a liquid fertilizer based on fish and kelp.

Follow package directions for dilution and application. The NASA researchers recommend using 15 to 18 good-sized plants to clear the air in an 1,800 square foot house.

So bring in some houseplants and take a deep breath.

If the plant's bottom leaves are close to the soil, trim them off so the soil is open to the air. Water the plants to keep the soil evenly moist, but not soggy, and feed them once a month with compost tea or a liquid fertilizer based on fish and kelp.

10 Plants To Clear Your Air
• Bamboo palm (Chamaedorea seifrizii), absorbs benzene, carbon monoxide, formaldehyde.
• Chinese evergreen (Aglaonema species), clears benzene, carbon monoxide, formaldehyde.
• Corn plant (Dracaena fragrans 'Massangeana'), absorbs formaldehyde>
• Dragon tree (Dracaena marginata), benzene, trichloroethylene.
• Florist's chrysanthemum (Dendrathema xgrandiflora), benzene, formaldehyde, trichloroethylene.
• English ivy (Hedera helix), benzene.
• Peace lily (Spathiphyllum cultivars), benzene, trichloroethylene.
• Golden pothos (Epipremnum aureum), formaldehyde. •
• Philodendron (Philodendron scandens), formaldehyde.
• Snake plant (Sansevieria trifasciata), formaldehyde.

Great sources for local potted plants include Marder's Nursery on Snake Hollow Road in Bridgehampton (631-537-3700), Lynch's Garden Center in Southampton (631-283-5515), Homeside Florist and Greenhouse in Riverhead (631-722-3380), and The Laurel Group at Baywoods in Water Mill (631-726-6610).

Anne Halpin is a writer, editor and professional gardener, and the author of 17 garden, home and nature books. She lives in Hampton Bays.