Ethanol vehicles pose significant risk to human health - study

Ethanol is widely touted as an eco-friendly, clean-burning fuel that reduces carbon dioxide emissions and thus helps mitigate catastrophic climate change. But if every vehicle in the United States ran on fuel made primarily from ethanol instead of pure gasoline, a side-effect would be that the number of respiratory-related deaths and hospitalizations would likely 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.

"Ethanol is being promoted as a clean and renewable fuel that will reduce global warming and air pollution," says 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 damage."

Gasoline versus 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. In addition, overall health effects depend on exposure to these airborne chemicals, which varies from region to region. Jacobson's 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:
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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.

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 hospitalizations
Jacobson 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 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. 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, Jacobson 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. 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 notes.

Alternatives
The researcher notes that there are alternatives, such as battery-electric, plug-in-hybrid and hydrogen-fuel cell vehicles, whose energy can be derived from renewables like wind and solar power. 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 large tracts of farmland to mass-produce.

The problem is that the economics of wind or solar generated electricity are currently not impressive. Biofuels used directly in indirect combustion engines or biomass used to generate electricity are between 2 to 40 times less costly than solar or wind power (earlier post). Moreover, batteries have a highly problematic life-cycle. Either current battery technology is not competitive yet (in the case of li-ion batteries) and the batteries that are competitive pose a huge waste-problem because they include toxic metals such as cadmium, cobalt, copper, nickel and iron whose disposal poses health risks and threaten to pollute water resources. Moreover, many of these metals are mined in developing countries under environmentally unsound conditions that threaten the health of thousands of poor people.

Finally, hydrogen used in fuel cells is costly to produce. If made from nuclear, wind or solar power, the costs are several times higher than if the hydrogen were to be made from fossil primary energy sources (coal, natural gas) or biomass (earlier post).

All technologies come with their drawbacks, ethanol is no different. If consumers decide the relatively small health risks associated with ethanol outweigh the advantage of less costly mobility, they will start buying electric or hydrogen powered fuel cell vehicles.

More information:
The study, "Effects of Ethanol (E85) Versus Gasoline Vehicles on Cancer and Mortality in the United States," by Mark Z. Jacobson, will appear in the April 18 online edition of Environmental Science & Technology (not online at the time this article was written).