EarthTalk: Now that autumn is here the leaves
are going to pile up in my yard again. Is it really that bad
to burn them? Why is it illegal to burn leaves in so many
-- Jeffrey Edwards, Westport, CT
Burning fallen leaves used to be standard practice across
North America, but most municipalities now ban or discourage
the incendiary practice due to the air pollution it causes.
The good news is that many towns and cities now offer curbside
pickup of leaves and other yard waste, which they then turn
into compost for park maintenance or for sale commercially.
And there are other burn-free options as well.
Because of the moisture that is usually trapped within leaves,
they tend to burn slowly and thus generate large amounts of
airborne particulates--fine bits of dust, soot and other solid
materials. According to Wisconsin’s Department of Natural
Resources, these particulates can reach deep into lung tissue
and cause coughing, wheezing, chest pain, shortness of breath
and sometimes long-term respiratory problems.
Leaf smoke may also contain hazardous chemicals such as carbon
monoxide, which can bind with the hemoglobin in the bloodstream
and reduce the amount of oxygen in the blood and lungs accordingly.
Another noxious chemical commonly present in leaf smoke is
benzo(a)pyrene, which has been shown to cause cancer in animals
and is believed to be a major factor in lung cancer caused
by cigarette smoke. And while breathing in leaf smoke can
irritate the eyes, nose and throat of healthy adults, it can
really wreak havoc on small children, the elderly and people
with asthma or other lung or heart diseases.
Sporadic individual leaf fires usually don't cause any major
pollution, but multiple fires in one geographic area can cause
concentrations of air pollutants that exceed federal air quality
standards. According to the U.S. Environmental Protection
Agency (EPA), several leaf and yard waste fires burning simultaneously
in a particular locale can cause air pollution rivaling that
from factories, motor vehicles and lawn equipment.
Purdue University consumer horticulture specialist Rosie Lerner
says that composting leaves is the most eco-friendly alternative
to burning. Dry leaves alone will take a long time to break
down, she says, but mixing in green plant materials, such
as grass trimmings, will speed up the process. Sources of
nitrogen, such as livestock manure or commercial fertilizer,
will also help. “Mix the pile occasionally to keep a
good supply of air in the compost,” she says, adding
that a compost pile should be a minimum of three cubic feet
and will generate soil conditioner within weeks or a few months,
depending on conditions.
Another option is to shred leaves for use as mulch for your
lawn or to help protect garden and landscape plants. Lerner
suggests adding no more than a two-to-three-inch layer of
leaves around actively growing plants, chopping or shredding
the leaves first so they don’t matt down and prevent
air from reaching roots.
As to using leaves as mulch for your lawn, it is just a simple
matter of mowing right over the leaves with the lawnmower
and leaving them there. As with leaves used for garden mulch,
this will provide many benefits, including weed suppression,
moisture conservation and moderation of soil temperature.
CONTACTS: U.S. EPA Residential Leaf Burning
“Composting for Beginners,” www.plowhearth.com/magazine/compost_how_to.asp.
COURTESY OF GETTY IMAGES
nice clean shower -- and so much more so with solar-heated
I heard that using a solar powered water heater in my home
would reduce my CO2 emissions significantly. Is this true?
And what are the costs? -- Anthony Gerst, Wapello, IA
According to mechanical engineers at the University of Wisconsin’s
Solar Energy Laboratory, an average four-person household
with an electric water heater needs about 6,400 kilowatt hours
of electricity per year to heat their water. Assuming the
electricity is generated by a typical power plant with an
efficiency of around 30 percent, it means that the average
electric water heater is responsible for about eight tons
of carbon dioxide (CO2) annually, which is almost double that
emitted by a typical modern automobile.
The same family of four using either a natural gas or oil-fired
water heater will contribute about two tons of CO2 emissions
annually in heating their water.
Surprising as it may seem, analysts believe that the annual
total CO2 produced by residential water heaters throughout
North America is roughly equal to that produced by all of
the cars and light trucks driving around the continent. Another
way of looking at it is: If half of all households used solar
water heaters, the reduction in CO2 emissions would be the
same as doubling the fuel-efficiency of all cars.
And that might not be such a tall order. According to the
Environmental and Energy Study Institute (EESI), there are
1.5 million solar water heaters already in use in U.S. homes
and businesses. Systems can work in any climate and EESI estimates
that 40 percent of all U.S. homes have sufficient access to
sunlight such that 29 million additional solar heaters could
be installed right now.
Another great reason to make the switch is a financial one.
According to the EESI, residential solar water heating systems
cost between $1,500 and $3,500 compared to $150 to $450 for
electric and gas heaters. With savings in electricity or natural
gas, solar water heaters pay for themselves within four to
eight years. They last between 15 and 40 years--the same as
conventional systems--so after that initial payback period
is up, zero energy cost essentially means having free hot
water for years to come.
What’s more, in 2005 the U.S. began offering homeowners
tax credits of up to 30 percent (capped at $2,000) of the
cost of installing a solar water heater. The credit is not
available for swimming pool or hot tub heaters, and the system
must be certified by the Solar Rating and Certification Corporation.
According to the U.S. Department of Energy’s “Consumer’s
Guide to Renewable Energy and Energy Efficiency,” zoning
and building codes relating to the installation of solar water
heaters usually reside at the local level, so consumers should
be sure to research the standards for their own communities
and hire a certified installer familiar with local requirements.
Homeowners beware: Most municipalities require a building
permit for the installation of a solar hot water heater onto
an existing house.
For Canadians looking to get into solar water heating, the
Canadian Solar Industries Association maintains a list of
certified solar water heater installers, and Natural Resources
Canada makes its informative booklet “Solar Water Heating
Systems: A Buyer’s Guide” available as a free
download on their website.
CONTACTS: U.S. Department of Energy, www.eere.energy.gov/consumer/;
Natural Resources Canada, www.canren.gc.ca/app/filerepository/AC5201041AFA42A1BFD51EA128F787CF.pdf.
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