Ethanol use in vehicle fuel is increasing worldwide, but the potential cancer risk and
ozone-related health consequences of a large-scale conversion from gasoline to ethanol
have not been examined. Here, a nested global-through-urban air pollution/weather
forecast model is combined with high-resolution future emission inventories, population
data, and health effects data to examine the effect of converting from gasoline to E85 on
cancer, mortality, and hospitalization in the U.S. as a whole and Los Angeles in
particular. Under the base-case emission scenario derived, which accounted for projected
improvements in gasoline and E85 vehicle emission controls, it was found that E85 (85%
ethanol fuel, 15% gasoline) may increase ozone-related mortality, hospitalization, and
asthma by about 9% in Los Angeles and 4% in the U.S. as a whole relative to 100%
gasoline. Ozone increases in Los Angeles and the northeast were partially offset by
decreases in the southeast. E85 also increased PAN in the U.S. but was estimated to cause
little change in cancer risk. Due to its ozone effects, future E85 may be a greater overall
public health risk than gasoline. However, because of the uncertainty in future emission
regulations, it can be concluded with confidence only that E85 is unlikely to improve air
quality over future gasoline vehicles. Unburned ethanol emissions from E85 may result in
a global-scale source of acetaldehyde larger than that of direct emissions.

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