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Dear EarthTalk:
Do houseplants really help to clean indoor air?
-- Jackson Schlemmer, London, England
One positive result of the 1970s energy crisis was the development
and widespread adoption of improved insulation materials to
maintain indoor energy efficiency. Unfortunately, however,
many of these materials have compromised indoor air quality
due to their tendency to “off-gas” various airborne
toxins, including formaldehyde, trichloroethylene (TCE), benzene
and other volatile organic compounds (VOCs).
Much of the synthetic carpeting, upholstery and paint used
indoors also contain sometimes noxious gases that get trapped
inside air-tight homes and offices and which can build up
gradually over time. And most synthetic air fresheners only
make matters worse, adding even more harmful VOCs to the indoor
air. With most people spending upwards of 90 percent of their
time indoors, it may be no coincidence that cases of asthma
and other respiratory diseases have been on the rise in recent
years.
The unlikely hero in this scenario may in fact be the humble
houseplant. In a landmark 1984 National Aeronautics and Space
Administration (NASA) study, initially commissioned to find
ways to clean air in space bases and vehicles, researcher
Bill Wolverton found that some common houseplants actually
cleaned polluted indoor air. He found that philodendrons and
golden pothos excelled at stripping formaldehyde from the
air, gerbera daisies and chrysanthemums wiped out excessive
amounts of indoor benzene, and pot mums and peace lilies absorbed
a toxic degreasing solvent known as TCE.
A later NASA study, also conducted by Wolverton, saw houseplants
removing up to 87 percent of toxic indoor air within 24 hours.
And a 1994 German study reported that one spider plant could
cleanse a small room of formaldehyde in just six hours. Further,
English ivy, bamboo palm and snake plants have been shown
to be effective in removing cigarette smoke as well as noxious
odors from carpeting and chemical-laden household cleaners.
Just how can a houseplant be so good at cleansing the air?
The reason lies in its basic ability to absorb carbon dioxide
from the air while releasing oxygen as part of the photosynthetic
process. Houseplants are essentially doing indoors what other
plants and trees ordinarily do outdoors.
To maximize the benefits of houseplants in cleaning indoor
air, it is generally recommended to use one plant for every
100 square feet of indoor space. Besides those plants mentioned
above, other good indoor air cleaners include palms, ferns,
dracaenas, corn plants, weeping figs, dumb canes, orchids,
arrowheads, dwarf bananas and Chinese evergreens.
For its part, the U.S. Environmental Protection Agency (EPA)
recommends opening the windows and letting in some good old-fashioned
fresh air as the best antidote to breathing in off-gassed
airborne toxins in both homes and offices. But many modern
buildings do not permit such exchanges between indoor and
outdoor air, and it is in just these situations where houseplants
can really make the difference.
CONTACT: Plant-Care.com; www.plant-care.com/indoor-plants-clean-air-1.html.
PHOTO
CREDIT: GETTY IMAGES
Some
70 percent of all antibiotics used are added to livestock
feed to ward off diseases and to promote growth.
Dear EarthTalk:
Why do modern bacteria “resist” antibiotics,
confounding medical treatment? -- Hugo Mestres, Seattle,
WA
Antibiotics have
played a profoundly important role in staving off bacterial
infections since Alexander Fleming first discovered them in
1927. But the effectiveness of these so-called miracle drugs
has waned in recent years as some of the very bacteria they
are meant to control have been mutating into new forms that
don't respond to treatment. Many medical experts blame this
phenomenon on both the misuse and overuse of antibiotics in
recent years in both human medicine and in agriculture.
Doctors first noticed antibiotic resistance more than a decade
ago when children with middle ear infections stopped responding
to them. Penicillin as a treatment for strep has also become
increasingly less effective. And a recently-discovered strain
of staph bacteria does not respond to antibiotic treatments
at all, leading medical analysts to worry that certain “super
bugs” could emerge that are resistant to even the most
potent drugs, rendering some infections incurable. The U.S.
Centers for Disease Control and Prevention (CDC) calls antibiotic
resistance one of its “top concerns” and “one
of the world’s most pressing health problems.”
One large part of the problem, according to the CDC, is the
tendency for people to take antibiotics to fight viruses,
which they cannot do. Antibiotics fight bacteria, not viruses,
and will not fight colds, flu, bronchitis, runny noses, or
sore throats not due to strep. Nonetheless, says CDC, “more
than 10 million courses of antibiotics are prescribed each
year for viral conditions that do not benefit from antibiotics.”
To address this, a growing number of doctors, including Dr.
Randel Cardott, an internist with Iowa’s Genesis Convenient
Care, are advocating a “wait-and-see” approach
to prescribing antibiotics, especially in cases like middle
ear infections that sometimes prove to be viral and not bacterial
in origin. Cardott says that European physicians have taken
this approach for years with no adverse effects.
Scaling back on antibiotics for human maladies won't address
the whole problem. Farmers and ranchers use antibiotics heavily,
too. In North America, industrial beef, pig and poultry farming
is a big unsanitary business, and antibiotics are used extensively
to ward off diseases and also for non-medical reasons, such
as to promote growth. In fact, the Union of Concerned Scientists
(UCS), a non-profit research and advocacy group, estimates
that some 70 percent of all antibiotics are used as additives
in the feed given to healthy pigs, poultry and cattle. These
drugs leave the animals’ bodies as waste and work their
way into local water supplies, as well as right into the food
chain. “Nonetheless,” says UCS, “agribusiness
and the pharmaceutical industry are fighting hard to thwart
restrictions on the use of antibiotics in agriculture.”
Keep Antibiotics Working, a non-profit dedicated to reducing
antibiotics overuse in agriculture, advocates phasing out
unnecessary antibiotics in healthy livestock and poultry.
In lieu of Congressional action along these lines, the group
is encouraging meat wholesalers and retailers to voluntarily
stop buying or selling meat that has been produced using antibiotics
for purposes other than treating sick animals. Consumers looking
to avoid antibiotics in meat should seek out organic offerings
at natural foods markets.
CONTACTS: UCS, www.ucsusa.org/food_and_environment/antibiotics_and_food/;
Keep Antibiotics Working, www.keepantibioticsworking.com.
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