Policy Positions: Ethanol’s Positive Impact on the Environment & Air Quality

Ethanol is one of the best tools available today to reduce air pollution from vehicles. Ethanol contains 35% oxygen, and adding oxygen to fuel results in more complete fuel combustion, thus reducing harmful tailpipe emissions. Ethanol is a high octane fuel and its use displaces toxic octane boosters such as benzene, a carcinogen. Ethanol is a virtually sulfur free additive and is biodegradable. Thus, it’s easy to see why many states use ethanol to reduce vehicular emissions.

Ethanol’s strongest air quality impact is in reducing carbon monoxide and toxics pollution. It also reduces particulates and total hydrocarbon emissions. Toxics, also known as Hazardous Air Pollutants (HAPs), and particulate matter (PM) are the most dangerous air pollutants to humans.

Ethanol is most commonly blended at 10% with gasoline (E10). It is also used as an alternative fuel, E85 (85% ethanol), designed for use in flexible fuel vehicles, and may be optimal in today’s vehicle fleet in higher blends than E10.

Ethanol Reduces Carbon Monoxide Emissions

According to the National Research Council, carbon monoxide (CO) emissions are responsible for as much as 20% of smog formation. Ethanol is the oxygenate of choice in the federal winter oxygenated fuels program in cities that exceed public health standards for CO pollution.

Ethanol Displaces Toxic Octane Boosters

According to the U.S. Environmental Protection Agency (EPA), today more than half of all Americans live in places where the air is unhealthy to breathe. The addition of octane-boosting ethanol replaces the use of toxic octane boosters, helping to make our air safer to breathe and reducing the cancer risks of driving and living near roadways. “Traffic presents a unique public health threat due to the toxicity of its emissions and its extensive integration into our lives and communities. The stakes are high and include epidemic proportions of excess cancer and child asthma rates,” according to Associate Professor Tim Buckley, Chair, Division of Environmental Health Sciences, the Ohio State University. A 1999 Colorado Department of Public Health and the Environment (CDPHE) study found that ethanol-blended gasoline reduced hydrocarbon pollution like benzene by 16.5% (source: “The Impact of 10% Ethanol Blended Fuel on Exhaust Emissions of Tier 0 and Tier 1 Light Duty Vehicles at 35 Degrees,” Ragazzi, et al.).

Ethanol Blends Reduce Soot Particulate Pollution

According to the American Lung Association, more than 2,000 studies link soot pollution to health problems like cancer, asthma and heart attacks. A growing number of studies demonstrate 10% ethanol blends reduce soot particulate pollution. The CDPHE study mentioned above found that E10 reduced soot pollution by 36% from newer vehicles and more in older, more polluting vehicles. A 2002 Journal of the American Medical Association study linked soot or fine particulate matter to lung cancer deaths, heart attacks, among other death-causing illnesses. For every 10 micrograms per cubic meter increase in soot pollution, lung cancer deaths increase 8%, heart attack deaths increase 6%, and all deaths increase 4%. (source: Pope, Clive Arden III; Richard P. Burnett, et al. Lung Cancer, Cardiopulmonary Mortality, and Long-term Exposure to Fine Particulate Air Pollution. Journal of the American Medical Association, March 6, 2002-Vol. 287, No. 92).

Ethanol Reduces Emissions from the Biggest Offenders

Over half of the air pollution attributable to vehicles comes from "high emitting" vehicles that make up only 10% of the vehicle fleet. High emitters include older vehicles as well as well as newer cars with malfunctioning pollution control systems. The use of ethanol-blended fuel is also one of the best pollution control strategies for off-road vehicles, including motorcycles, ATVs and snowmobiles, which represent a significant source of emissions. Source: Smog Reyes, February 2004

Ethanol’s Impact on NOx/VOCs

There has been much debate on ethanol’s impact on emissions of NOx and volatile organic compounds (VOCs). In parts of the country with the worst smog pollution (ozone nonattainment areas), the U.S. EPA requires the use of federal reformulated gasoline (RFG). The state of California enforces its own more stringent state RFG program. It is important to note that both RFG programs do not allow refiners to market gasoline blends that increase emissions of pollutants (such as NOx) over an established baseline fuel, whether they contain ethanol or not. Refiners, then, must adjust other fuel parameters to “zero out” any NOx response from ethanol (again, assuming one is assessed by the regulation) or any other fuel constituent. For example, an E10 ethanol blend might have lower sulfur levels than gasoline without ethanol, because a refiner decided to reduce sulfur levels to produce a NOx compliant ethanol fuel. Thus, ethanol-blended RFG meets the same evaporative emission standard as gasoline without ethanol.

The net public health impact of using biofuels is beneficial. Ethanol blending significantly reduces emissions of pollutants that are generally believed to pose the greatest public health threat (PM and Toxics); and, the actual ozone impact of the alleged increases in NOx and VOC emissions, if assumed to be true, is negligible or extremely small. (Source: A Northeast Regional Biomass Plan). For it is generally accepted that ethanol reduces emissions of PM and HAPs, and that mobile sources account for a vast majority of human exposure to HAPs and a significant portion of human exposure to PM.

Various airshed models suggest that the use of ethanol (E10), even while assuming slight increases in NOx and/or VOCs, does not measurably increase actual ozone levels. These photochemical airshed models are generally accepted as the most accurate way to measure the actual ozone impacts of various fuels and emissions. Thus, the “alleged” negative emissions responses from biofuel blending do not lead to a measurable impact on smog levels, which in turn means that the use of biofuels is extremely unlikely to jeopardize ozone attainment. “As such, it is reasonable to suggest that the public health benefit of reduced particulate and HAP exposure is greater than the negligible deleterious smog impact of any NOx and VOC emissions increases.” (“A Northeast Regional Biomass Plan,” R. Brooke Coleman, New Fuels Alliance, March 2008, http://www.nebiofuels.org/pdfs/NERegionalReportFINAL.pdf).