Go Green! > Helpful Houseplants
It’s the time of year when we yearn for all things green as the wintry landscape surrounds us in a white blanket. Our gardens sleep, put to bed until the next growing season. The dry, heated air inside our homes makes us recall the hot and humid days of summer with fondness as scratchy throats prevail. If you relish advancing springtime, try creating what designers call a “tended space” indoors. Adding some interior landscaping with houseplants to your home may brighten your days and improve the quality of the air you breathe.
Many of the products used in homes today—from paint to flooring—release chemicals into the air. When this is combined with newer construction standards that create a tighter building “envelope” (the barrier between the inside and outside environment, such as the walls and roof), we breathe in the airborne chemicals.
How plants work to improve air quality
B.C. “Bill” Wolverton—author of How to Grow Fresh Air and Growing Clean Water: Nature’s Solution to Environmental Pollution(with John D. Wolverton, currently out of print)— has focused his work on green plants and how their life processes could be used to create and clean air.
“There are two major mechanisms by which plants do this,” says Wolverton, who retired from NASA after working in the early seventies on research that sought to mimic the Earth’s environment for extended human habitation on the moon or in space stations. “First, certain chemicals— like formaldehyde [a chemical classified as a volatile organic compound (VOC) used as an adhesive, bonding agent and solvent that may be found in home products such as plywood and other pressedwood products]—can be absorbed by the leaves and broken down. Second, when plants transpire [breathe], they emit moisture and pull the air down to their roots to create an aerobic condition for their roots and associated microbes. They consequently pull down the airborne chemical into the soil.
“The major function of a plant is to grow the microbes and then the microbes convert toxic chemicals into a source of food and energy for the plants,” Wolverton continues in a telephone interview from his home in Mississippi. This process is called photosynthesis.
Wolverton’s NASA research evaluated plants for their ability to remove toxins, ease of growth, resistance to insects and transpiration rate (how quickly a plant takes in air and gives off moisture). The goal was to create what he calls a “bioregenerating plant filter system” for the air. “In 1989, the EPA [U.S. Environmental Protection Agency] did an analysis and found that as many as nine hundred varieties of low-levels of VOCs were present in public buildings, representing a major threat to people,” says Wolverton.
While most houseplants are grown in pots with soil, if you’re lucky enough to have an attached greenhouse or sunspace, you may reap even more benefits from plants grown in alternative mediums. Wolverton notes that when plants are grown hydroponically in stable mediums—such as expanded shale or clay pebbles— their efficiency in cleaning the air increases by between 30 percent and 50 percent because it is easier for the plant to pull the air down and for the microbes to grow.
You need more than plants for clean indoor air
Jessica Morton, indoor air quality specialist with the New Hampshire Department of Environmental Services, notes that using plants to clean indoor air is only part of a whole-house solution. “Plants alone won’t solve your indoor air quality problem,” she says, adding that they need to have the proper care.
She cautions that when you have multiple plants, over-watering them could cause mold to grow and possibly create other health issues. Morton prefers to rely on the four principles of healthy homes suggested by the U.S. Environmental Protection Agency: keep the home dry, clean, ventilated and pest-free.
If you are interested in testing your indoor air quality, she recommends finding a professional licensed by the American Board of Industrial Hygiene (www.abih.org) or the American Indoor Air Quality Council (www.iaqcouncil.org)
Plants for your indoor ecological garden
Wolverton’s NASA study showed that palms proved to be the most effective plants overall at improving air quality due to their ability to pump out so much moisture. Wolverton (who has degrees in medical microbiology and chemical engineering) recommends the Areca palm (Chrysalidocarpus lutescens), a medium- textured plant with thin ribbons of green fronds, and the Lady palm (Rhapis excelsa), which features both green and variegated varieties. His research lists the top plants for improving indoor air (see NASA’s Top Houseplants for Improving Air Quality on the facing page).
Many houseplants are varieties of tropical vegetation that are accustomed to growing beneath tall trees in the forest and tolerant of low light levels. Check the minimum exposure a plant needs before you buy it to be sure it will thrive in your chosen location.
Keeping the leaves of your plants dust-free will improve how they function, allowing them to breathe more easily while reducing the allergen factor in your home. Plants also like humidity, so a weekly spritz with the water mister will be appreciated. The Web site cleanairgardening.com, following the NASA guidelines, recommends about fifteen of the plants for a house of less than two thousand square feet be grown in six-inch containers for optimum benefit.
Wolverton also notes that a bonus to plants with a high moisture rate is that they produce negative ions for the indoor atmosphere that studies show may provide a psychological boost.
So sit back, breathe deeply and relax in the company of your new houseplants that are working for you to support a healthy lifestyle.
January is National Radon Action Month
In the Granite State—and many parts of the Northeast—you could be living with radon, a naturally produced radioactive gas that you can’t smell in the air or taste if it is in your water supply. During the winter, when homes are more airtight, the possibility of trapping radon gas—an EPA-labeled carcinogen—inside increases.
The solution is simple: Test your home’s air and water for radon. And, if necessary, install a radon abatement system to exhaust the gas. Do-it-yourself test kits are available from:
• State-certified laboratories;
• By calling the New Hampshire Department of Environmental Services, Radon Program, (800) 852-3345, extension 4610; and
• By calling (800) SOS-RADON (767- 7236).
For more information, see the EPA’s Web site, www.epa.gov/radon.