Motor vehicles running on ethanol
may be more harmful to human health
than vehicles running on petrol.
A study conducted by Stanford
University and published in the online
edition of Environmental Science and
Technology has revealed the shocking
fact that if a majority of vehicles
used ethanol, the ground level ozone
showed an alarming increase.
Ozone, which is a pollutant, is known
to cause serious damage to the
respiratory system. Increase in smog
levels would contribute to an
additional 200 deaths a year in the
United States, the study found.
The results of the study were based on
a computer simulation model run by
Mark Jacobson, an atmospheric
scientist at Stanford University. The
model is based on the quality of air
in 2020 if all vehicles were to shift
to ethanol for fuel. The model also
takes into account factors like
sunlight, temperatures clouds and rain
to produce simulations of air quality.
Ethanol is widely touted as an
eco-friendly, clean-burning fuel, but
if every vehicle in the United States
ran on fuel made primarily from
ethanol instead of pure gasoline, the
number of respiratory-related deaths
and hospitalisations is likely to go
up.
The chemicals that come out of a
tailpipe are affected by a variety of
factors, including chemical reactions,
temperatures, sunlight, clouds, wind
and precipitation. Besides, Mark
Jacobson said, overall health effects
depend on exposure to these airborne
chemicals, which varies from region to
region.
Stanford University’s was the first
study on ethanol that took into
account population distribution and
the complex environmental
interactions.
For the study, Jacobson used a
sophisticated computer model to
simulate air quality in the year 2020,
when ethanol-fueled vehicles are
expected to be widely available in the
United States, with a special focus on
Los Angeles. “Since Los Angeles has
historically been the most polluted
airshed in the United States, the
testbed for nearly all US air
pollution regulation and home to about
6% of the US population, it is also
ideal for a more detailed study,” Mark
Jacobson said.
He programmed the computer to run air
quality simulations comparing two
future scenarios:
* A vehicle fleet (that is, all
cars, trucks, motorcycles, etc., in
the United States) fueled by gasoline,
versus
* A fleet powered by E85, a popular
blend of 85% ethanol and 15% gasoline.
The results of the computer
simulations were striking, according
to Mark Jacobson.
The researchers found that E85
vehicles reduce atmospheric levels of
two carcinogens, benzene and
butadiene, but increase two
others-formaldehyde and acetaldehyde.
As a result, cancer rates for E85 are
likely to be similar to those for
gasoline. However, in some parts of
the country, E85 significantly
increased ozone, a prime ingredient of
smog.
Inhaling ozone, even at low levels,
can decrease lung capacity, inflame
lung tissue, worsen asthma and impair
the body’s immune system, according to
the US Environmental Protection
Agency. The World Health Organisation
estimates that 800,000 people die each
year from ozone and other chemicals in
smog.
Mark Jacobson said that switching
vehicles to operate on batteries and
electricity could avoid 10,000
pollution-related deaths each year.
Jennifer Wood of the US Environmental
Protection Agency reacted to the
study, saying that ethanol would
reduce greenhouse gas emissions and
would help farming communities in the
country. The pollutants that
contribute to ozone, which may
slightly increase as a result of
additional ethanol use, can be managed
by the suite of effective tools
available under the Clean Air Act, she
stressed.
