Stanford Report, April
Ethanol vehicles pose significant risk to health, new
BY MARK SHWARTZ
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 hospitalizations likely would increase,
according to a new study by Stanford University
atmospheric scientist Mark Z. Jacobson. His findings are
published in the April 18 online edition of the journal
Environmental Science & Technology (ES&T).
"Ethanol is being promoted as a clean and renewable fuel
that will reduce global warming and air pollution," said
Jacobson, associate professor of civil and environmental
engineering. "But our results show that a high blend of
ethanol poses an equal or greater risk to public health
than gasoline, which already causes significant health
Gasoline vs. ethanol
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.
"The chemicals that come out of a tailpipe are affected
by a variety of factors, including chemical reactions,
temperatures, sunlight, clouds, wind and precipitation,"
he explained. "In addition, overall health effects
depend on exposure to these airborne chemicals, which
varies from region to region. Ours is the first ethanol
study that takes into account population distribution
and the complex environmental interactions."
In the experiment, Jacobson ran a series of computer
tests simulating atmospheric conditions throughout the
United States in 2020, with a special focus on Los
Angeles. "Since Los Angeles has historically been the
most polluted airshed in the U.S., the testbed for
nearly all U.S. air pollution regulation and home to
about 6 percent of the U.S. population, it is also ideal
for a more detailed study," he wrote.
Jacobson 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 percent
ethanol and 15 percent gasoline. Deaths and
The results of the computer simulations were striking.
"We found that E85 vehicles reduce atmospheric levels of
two carcinogens, benzene and butadiene, but increase two
others—formaldehyde and acetaldehyde," Jacobson said.
"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 Environmental
Protection Agency. The World Health Organization
estimates that 800,000 people die each year from ozone
and other chemicals in smog.
"In our study, E85 increased ozone-related mortalities
in the United States by about 200 deaths per year
compared to gasoline, with about 120 of those deaths
occurring in Los Angeles," Jacobson said. "These
mortality rates represent an increase of about 4 percent
in the U.S. and 9 percent in Los Angeles above the
projected ozone-related death rates for gasoline-fueled
vehicles in 2020."
The study showed that ozone increases in Los Angeles and
the northeastern United States will be partially offset
by decreases in the southeast. "However, we found that
nationwide, E85 is likely to increase the annual number
of asthma-related emergency room visits by 770 and the
number of respiratory-related hospitalizations by 990,"
Jacobson said. "Los Angeles can expect 650 more
hospitalizations in 2020, along with 1,200 additional
asthma-related emergency visits."
The deleterious health effects of E85 will be the same,
whether the ethanol is made from corn, switchgrass or
other plant products, Jacobson noted. "Today, there is a
lot of investment in ethanol," he said. "But we found
that using E85 will cause at least as much health damage
as gasoline, which already causes about 10,000 U.S.
premature deaths annually from ozone and particulate
matter. The question is, if we're not getting any health
benefits, then why continue to promote ethanol and other
"There are alternatives, such as battery-electric,
plug-in-hybrid and hydrogen-fuel cell vehicles, whose
energy can be derived from wind or solar power," he
added. "These vehicles produce virtually no toxic
emissions or greenhouse gases and cause very little
disruption to the land—unlike ethanol made from corn or
switchgrass, which will require millions of acres of
farmland to mass-produce. It would seem prudent,
therefore, to address climate, health and energy with
technologies that have known benefits."
Stanford University - This ES&T study was partially
supported by NASA