Several examples of EPA’s standards for gasoline are listed below (EPA 2013):
- The Gasoline Sulfur program was phased-in from 2004 to 2007. Refiners can produce gasoline with a range of sulfur levels as long as their annual corporate average does not exceed 30 parts per million (ppm). In addition, no individual batch can exceed 80 ppm. Sulfur can adversely affect catalysts and may also be emitted as a sulfur oxide.
- The Mobile Source Air Toxics (MSAT) rules reduce hazardous air pollutants, also known as air toxics, emitted by cars and trucks. Air toxics include benzene and other hydrocarbons such as 1,3-butadiene, formaldehyde, acetaldehyde, acrolein, and naphthalene.
- Reformulated Gasoline (RFG) was mandated for metropolitan areas with the worst smog beginning in 1995. RFG is a blended oxygenated fuel which burns cleaner than conventional gasoline, reducing emissions of smog-forming and toxic pollutants.
- EPA regulates the volatility/Reid Vapor Pressure (RVP) of conventional gasoline sold at retail stations during the summer smog season to reduce evaporative emissions that contribute to smog.
- Winter Oxygenate Fuel programs increase fuel oxygen and are mandated in certain areas for carbon monoxide control.
- E15 is a fuel containing a mixture of gasoline and ethanol, specifically 15-volume percent ethanol and 85-volume percent gasoline. EPA has granted a partial waiver to allow E15 to be introduced into commerce for use in model year 2001 and newer light-duty motor vehicles, subject to several conditions.
- Phosphorous in limited to 0.0013 g P/L since it can adversely affect exhaust catalysts.
- ASTM standards include D4814 - 13a, Standard Specification for Automotive Spark-Ignition Engine Fuel. All fuels must comply with various properties contained in this specification. Antiknock Index (AKI) is defined as the Research Octane Number + Motor Octane Number divided by two. AKI limits are not specified in the ASTM standards. AKI limits change with engine requirements and according to season and location. Fuels with an AKI of 87, 89, 91 are listed as typical for the U.S. at sea level, however higher altitudes will specify lower octane numbers.
EPA (Environmental Protection Agency). 2013. Control of Air Pollution From Motor Vehicles: Tier 3 Motor Vehicle Emission and Fuel Standards. Proposed Rule, Federal Register, Vol. 78, No. 98.