Indicators of Human Health Impacts from Ethanol and Gasoline Lifecycle Air Emissions

Traditional lifecycle assessments have compared corn-based ethanol and unleaded gasoline for global warming, acidification, and eutrophication influences without adequately addressing the fuels' human toxicity impacts. This work quantifies indicators of human health impacts from ethanol and gasoline lifecycle air emissions. It also illustrates the shift in regional pollution associated with producing more ethanol as a gasoline substitute, as mandated by U.S., the Energy Independence and Security Act (EISA) of 2007. Emissions from increased corn growing and ethanol production will add to the health burden of people in the Midwest, but displace some of the petroleum impacts that people along the Gulf of Mexico currently endure.

Emission inventories from the Swiss Centre for Life Cycle Inventories' ecoinvent v2.0 database are multiplied by inhalation toxicity weights from the U.S. EPA's Risk-Screening Environmental Indicators (RSEI) computer-based screening tool to generate regional pollution profiles. During the production of corn-based ethanol, there are fewer emissions and lower human health impacts in both low and high population density areas than during the production of gasoline. There is, however, uncertainty in this analysis due to the inability to quantify all emissions based on the specific molecular species. Some of the emissions are aggregated and reported as “non-methane volatile organic compounds from unspecified origins.” When these are excluded from production emissions inventories, corn-based ethanol's production emissions per vehicle mile create a higher human health impact than those of unleaded gasoline.