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Additive Laws for MTB & Ethanol Gas

The Clean Air Act is designed to improve and maintain air quality. One issue that receives a lot of regulatory attention is ozone pollution, a primary public health issue due to its contribution to lung ailments, such as asthma. Ozone is regulated by limiting volatile organic compounds (VOC) to safe levels from various sources, including mobile sources. Under the Mobile Source Air Toxic (MSAT) regulations (40 CFR Parts 59, 80, 85 and 86), the Environmental Protection Agency (EPA) requires that reformulated gasoline sold in certain areas be oxygenated to reduce VOCs; oil companies do so by adding methyl tertiary-butyl-ether (MTBE) or ethanol to achieve acceptable levels.

  1. VOC Control Areas

    • The EPA has designated certain areas as VOC Control Areas. These areas already have high levels of VOCs, significant smog pollution, high tropospheric ozone levels, and most importantly, high incidences of public health lung issues. Reformulated gasoline is required to be dispensed in designated VOC control regions (40 CFR 80.71). In 2010, reformulated gasoline was used in 17 states and the District of Columbia--30 percent of the gasoline sold in the United States.

    Reformulated Gasoline

    • MTBE or ethanol is added to gasoline at the refinery to meet federally mandated standards for increased oxygen content.

      Each oil company that produces or imports gasoline prepares its own formula that must meet federal emission reduction standards. The basic requirements for compliance include reid vapor pressure less than or equal to 7.2 pounds per square inch, oxygen content greater than or equal to 2.0 percent by weight, toxic air pollutant reduction greater or equal to 15 percent and benzene less than or equal to 1 percent by volume weight (40 CFR 80.41).

    Oxygenated Additives for Reformulated Gasoline

    • The EPA only requires that reformulated gasoline be oxygenated. The agency does not require a specific additive (the oil companies maintain control over whether MTBE or Ethanol is used to achieve standards). According to the EPA, approximately 87 percent of the reformulated gasoline in the United States uses MTBE because it is less volatile and thus easier to meet overall emission standards. In any case, whatever additive is used, the EPA requires that reformulated gasoline be labeled at point of sale, stating: "The gasoline dispensed from this pump is oxygenated and will reduce carbon monoxide pollution from motor vehicles" (40 CFR 80.35). Carbon monoxide, lead, nitrogen, VOCs (ozone), particulate matter and sulfur dioxide are all regulated under the MSAT standards designed to reduce lung problems as well as the environmental impacts associated with acid rain. Therefore, the reformulated gasoline requirements for VOC decreases are part of overall air quality standards for mobile sources.

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