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Dear
EarthTalk: I know that global warming causes
extreme weather and melts glaciers and causes sea level rises.
But how does it increase the spread of disease?
-- Curran Clark, Seattle, WA
Climate
change accelerates the spread of disease primarily because
warmer global temperatures enlarge the geographic range in
which disease-carrying animals, insects and microorganisms--as
well as the germs and viruses they carry--can survive. Analysts
believe that, as a result of global temperature rises, diseases
that were previously limited only to tropical areas may show
up increasingly in other, previously cooler areas.
For
example, mosquitoes carrying dengue fever used to dwell at
elevations no higher than 3,300 feet, but because of warmer
temperatures they have recently been detected at 7,200 feet
in Colombia’s Andes Mountains. And biologists have found
malaria-carrying mosquitoes at higher-than-usual elevations
in Indonesia in just the last few years. These changes happen
not because of the kinds of extreme heat we’ve experienced
in recent months, but occur even with minuscule increases
in average temperature.
But
extreme heat can also be a factor, and the nexus of global
warming and disease really hit home for North Americans in
the summer of 1999, when 62 cases of West Nile virus were
reported in and around New York City. Dr. Dickson Despommier,
a Columbia University public health professor, reports that
West Nile Virus is spread by one species of mosquito that
prefers to prey on birds, but which will resort to biting
humans when its normal avian targets have fled urban areas
during heat waves.
“By
reproductive imperative, the mosquitoes are forced to feed
on humans, and that’s what triggered the 1999 epidemic,”
Despommier says. “Higher temperatures also trigger increased
mosquito biting frequency. The first big rains after the drought
created new breeding sites.” He adds that a similar
pattern has been recognized in other recent West Nile outbreaks
in Israel, South Africa and Romania.
Bird
flu is another example of a disease that is likely to spread
more quickly as the Earth warms up, but for a different reason:
A United Nations study found that global warming--in concert
with excessive development--is contributing to an increased
loss of wetlands around the world. This trend is already forcing
disease-carrying migrating birds, who ordinarily seek out
wetlands as stopping points, to instead land on animal farms
where they mingle with domestic poultry, risking the spread
of the disease via animal-to-human and human-to-human contact.
A
Congressionally-mandated assessment of climate change and
health conducted in 2001 predicted that global warming will
cause or increased incidences of malaria, dengue fever, yellow
fever, encephalitis and respiratory diseases throughout the
world in coming decades. The assessment also concluded that
insect- and rodent-borne diseases would become more prevalent
throughout the U.S. and Europe.
The
news isn’t good for less developed parts of the world
either. Researchers have found that more than two-thirds of
waterborne disease outbreaks (such as cholera) follow major
precipitation events, which are already increasing due to
global warming.
CONTACTS:
Natural Resources Defense Council Consequences of Global Warming,
www.nrdc.org/globalWarming/fcons.asp.
Dear EarthTalk:
I’m going to be remodeling and was wondering: Are there
floorings or wall coverings available that won’t aggravate
my child’s respiratory problems?
-- Mary, Lake Zurich, IL
For those with
chemical sensitivities, the home is sometimes anything but
a refuge. Volatile organic compounds (VOCs) such as formaldehyde
can “off-gas” from carpets, wallpaper and paints,
irritating lungs and promoting headaches and itchy eyes. Luckily,
there are increasingly more options to traditional building
materials and furnishings that are both kinder to Mother Earth
and safer for our health.
For flooring, the
Seattle-based Environmental Home Center recommends cork, linoleum,
bamboo and selected hardwoods as the best choices from an
indoor air quality standpoint. If you choose any of these
options, make sure installers use non-toxic adhesives as the
devil--leaking VOCs--is often in such details.
For those seeking
something plusher underfoot, Earth Weave and Natural Home,
among others, use natural fibers such as wool, jute, hemp
and rubber to create attractive, chemical-free carpeting for
both wall-to-wall and area rug applications. Both companies
avoid toxic dyes and mothproofing as well as stain-repellents,
relying instead upon the natural resiliency of the materials
they incorporate.
And don’t
stop at the carpet. All-natural wool padding, which is usually
needled together to avoid the VOCs often found in adhesives,
will keep the top layer soft without introducing toxins to
the underfoot mix. Traditional carpets and pads can off-gas
a smorgasbord of noxious chemicals, including VOCs.
A raft of new wall-coverings
has also come to the rescue in recent years. Most wallpaper
is not made from paper at all, but from a malleable plastic
called polyvinyl chloride (PVC), which generates several known
carcinogens, including dioxin, during its production. One
green alternative is Sherwin-Williams’ non-vinyl Easychange
brand. Made from paper, it requires no special solvents or
adhesives to install, and is stocked in a variety of designs
and styles. Another good choice is Pallas Textiles’
DialTones line, made from discarded phonebooks. Also, Environmental
Home Center makes its own Innovations brand, which is made
from nontoxic polyester and wood pulp, using water-based inks
completely free of heavy metals.
In the paints category,
there are now many non-toxic or low-VOC offerings, including
AFM Safecoat, Livos, BioShield, Yolo and Olivetti. GreenHome.com
stocks many of these, and mainstream paint dealers may carry
eco-friendly paints from more familiar names, like Benjamin
Moore or Sherwin-Williams.
Remodelers beware,
though: Changing out your flooring and wall coverings won’t
banish chemical irritants entirely. Many homes built or remodeled
during the 1970s were insulated with formaldehyde foam, which
can remain a health nuisance long after installation. Luckily,
there are now plenty of greener insulation choices, such as
cellulose, cotton and radiant metal barriers. Open-cell spray
insulations such as Icynene or Air Krete are also popular
with green builders, as they are effective, inexpensive and
easy to apply. Some of these products are available at Home
Depot and Lowe’s, but small green building supply retailers
can be researched at GreenerBuilding.org.
CONTACTS:
Environmental Home Center, www.environmentalhomecenter.com;
GreenHome.com, www.greenhome.com;
GreenerBuilding.org, www.greenerbuilding.org.
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