Cultivating the power of houseplants

The science may be sketchy, but many swear by = greenery=20

Sunday, April 02, 2006

BY AMY WHITESALL

News Staff Reporter

Biology professor Annie Hannan helps the houseplant-challenged. = As part=20 of an indoor gardening class she teaches, students learn how not = to kill=20 their plants, while they develop a deeper appreciation for the = things that=20 plants can do. Plants can soften cubicle-filled workplaces, Hannan = points=20 out. They muffle noise.

Most are surprised, though, when Hannan tells them the = houseplants=20 they've been nurturing can help clean the air in their homes.

"What people tell me is they feel empowered by it,'' says = Hannan, whose=20 class is one of Eastern Michigan University's continuing education = offerings. "First of all they're extremely troubled to learn that = the=20 indoor air is so polluted. They feel so powerless, and then here's = this=20 possible solution.

"Plus, it makes you feel a good sense of accomplishment that = you're=20 helping your health and helping your family's health by growing = these=20 plants.''

The best-known science regarding houseplants and air quality = came out=20 of a series of NASA studies in the 1970s, when the space agency = was=20 looking for ways to clean trace amounts of more than 300 volatile = organic=20 compounds from the air inside the Skylab spacecraft. Environmental = engineer Bill Wolverton found that several common houseplants, = when placed=20 individually in a sealed chamber with specifically polluted air, = did the=20 job.

As plants pull water through the soil toward their roots they = pull air=20 along with it. Some compounds get trapped in the soil, and mixing=20 activated charcoal (the kind that's used in aquarium filters) with = the=20 potting soil will help snag more. Beyond that, plant physiologists = aren't=20 sure how it happens, but Wolverton showed plants dramatically = reduced the=20 levels formaldehyde, benzene, paratrichloroethylene, toluene, = carbon=20 monoxide and nitrogen dioxide in that sealed chamber. He would = later write=20 a book, "How to Grow Fresh Air,'' that details just which plants = are best=20 at removing what. Wolverton eventually concluded that 15 to 20 = potted=20 plants should be able to clean certain toxins in the air in an=20 1,800-square-foot house.

It's a claim the Environmental Protection Agency has chosen not = to=20 endorse, although the difference seems to hinge on the number of = plants it=20 would take to clean the air in a house, which is by no means a = sealed=20 chamber.

"The sheer number of houseplants per square foot to improve air = quality=20 in your house would turn your house into a jungle,'' says EPA = press=20 officer Roxanne Smith. "Basically we don't see any valid signs = that would=20 lead us to support the claim that houseplants improve indoor air = quality.=20 We would need to see some peer-reviewed science to make a comment = on it.''=20

So can houseplants clean the air in your home? It depends on = your home,=20 and on what you want to clean out of the air.

Older, draftier buildings aren't as likely to develop = concentrations of=20 off-gassed pollutants. But newer homes and offices can, especially = if=20 they're not well ventilated. Formaldehyde is in many construction=20 materials. Toluene is used as a solvent in some glues, paints and=20 thinners; paratrichloroethylene turns up in glues, paints, = cleaners,=20 insecticides and fungicides. Breathing the fumes of these = compounds can=20 cause symptoms that include headaches, nausea, dizziness, and eye = and lung=20 irritation.

In addition to Wolverton's research, Hannan says, there's lots = of=20 anecdotal evidence of these symptoms disappearing after plants = were=20 brought in.

But plants can't do everything. They don't clear the air of = dust, mold,=20 animal dander, dust mites, asbestos, radon or the fumes from many=20 household cleaning products. In fact, if they can gather dust and, = if=20 overwatered or poorly drained, develop mold. Plus you have to take = care of=20 them. But in Hannan's opinion, the potential benefits outweigh the = drawbacks.

"The presence of houseplants have a very soothing effect on = people.=20 There's a cheerfulness that they create. ... Obviously my house = and your=20 house are going to be different from a lab, but it seems as though = particular houseplants have the ability, to some degree, to remove = these=20 specific toxins from the air,'' Hannan says. "From my perspective, = can it=20 hurt?''

Amy Whitesall can be reached at 734-994-6679 or=20 awhitesall@annarbornews.com.



Cultivating the power of houseplants The science may be sketchy, but many swear by = greenery=20 Sunday, April 02, 2006 BY AMY WHITESALL News Staff Reporter Biology professor Annie Hannan helps the houseplant-challenged. = As part=20 of an indoor gardening class she teaches, students learn how not = to kill=20 their plants, while they develop a deeper appreciation for the = things that=20 plants can do. Plants can soften cubicle-filled workplaces, Hannan = points=20 out. They muffle noise. Most are surprised, though, when Hannan tells them the = houseplants=20 they've been nurturing can help clean the air in their homes. "What people tell me is they feel empowered by it,'' says = Hannan, whose=20 class is one of Eastern Michigan University's continuing education = offerings. "First of all they're extremely troubled to learn that = the=20 indoor air is so polluted. They feel so powerless, and then here's = this=20 possible solution. "Plus, it makes you feel a good sense of accomplishment that = you're=20 helping your health and helping your family's health by growing = these=20 plants.'' The best-known science regarding houseplants and air quality = came out=20 of a series of NASA studies in the 1970s, when the space agency = was=20 looking for ways to clean trace amounts of more than 300 volatile = organic=20 compounds from the air inside the Skylab spacecraft. Environmental = engineer Bill Wolverton found that several common houseplants, = when placed=20 individually in a sealed chamber with specifically polluted air, = did the=20 job. As plants pull water through the soil toward their roots they = pull air=20 along with it. Some compounds get trapped in the soil, and mixing=20 activated charcoal (the kind that's used in aquarium filters) with = the=20 potting soil will help snag more. Beyond that, plant physiologists = aren't=20 sure how it happens, but Wolverton showed plants dramatically = reduced the=20 levels formaldehyde, benzene, paratrichloroethylene, toluene, = carbon=20 monoxide and nitrogen dioxide in that sealed chamber. He would = later write=20 a book, "How to Grow Fresh Air,'' that details just which plants = are best=20 at removing what. Wolverton eventually concluded that 15 to 20 = potted=20 plants should be able to clean certain toxins in the air in an=20 1,800-square-foot house. It's a claim the Environmental Protection Agency has chosen not = to=20 endorse, although the difference seems to hinge on the number of = plants it=20 would take to clean the air in a house, which is by no means a = sealed=20 chamber. "The sheer number of houseplants per square foot to improve air = quality=20 in your house would turn your house into a jungle,'' says EPA = press=20 officer Roxanne Smith. "Basically we don't see any valid signs = that would=20 lead us to support the claim that houseplants improve indoor air = quality.=20 We would need to see some peer-reviewed science to make a comment = on it.''=20 So can houseplants clean the air in your home? It depends on = your home,=20 and on what you want to clean out of the air. Older, draftier buildings aren't as likely to develop = concentrations of=20 off-gassed pollutants. But newer homes and offices can, especially = if=20 they're not well ventilated. Formaldehyde is in many construction=20 materials. Toluene is used as a solvent in some glues, paints and=20 thinners; paratrichloroethylene turns up in glues, paints, = cleaners,=20 insecticides and fungicides. Breathing the fumes of these = compounds can=20 cause symptoms that include headaches, nausea, dizziness, and eye = and lung=20 irritation. In addition to Wolverton's research, Hannan says, there's lots = of=20 anecdotal evidence of these symptoms disappearing after plants = were=20 brought in. But plants can't do everything. They don't clear the air of = dust, mold,=20 animal dander, dust mites, asbestos, radon or the fumes from many=20 household cleaning products. In fact, if they can gather dust and, = if=20 overwatered or poorly drained, develop mold. Plus you have to take = care of=20 them. But in Hannan's opinion, the potential benefits outweigh the = drawbacks. "The presence of houseplants have a very soothing effect on = people.=20 There's a cheerfulness that they create. ... Obviously my house = and your=20 house are going to be different from a lab, but it seems as though = particular houseplants have the ability, to some degree, to remove = these=20 specific toxins from the air,'' Hannan says. "From my perspective, = can it=20 hurt?'' Amy Whitesall can be reached at 734-994-6679 or=20 awhitesall@annarbornews.com. =A92006 Ann Arbor News =A9 2006 Michigan Live. All Rights=20 Reserved.