Title III Hazardous Air Pollutants

The Act established the National Emissions Standards for Hazardous Air Pollutants (NESHAPS) to regulate air pollutants designated by the EPA as hazardous. The EPA was directed to identify hazardous air pollutants (HAPs) that might have health effects, and then establish control standards for selected significant sources of these pollutants, restricting emissions to a level that produces no adverse health effects. This approach, however, was difficult to implement. Scientific controversy surrounding the identification of a "safe" exposure level made it very difficult for the EPA to write its regulations. Between 1970 and 1990, the EPA was only able to establish NESHAPS for certain sources of radon, beryllium, mercury, vinyl chloride, radionuclides, benzene, asbestos, and arsenic. Congress developed a new approach in the CAAA and shifted the regulatory emphasis from a risk-based approach to a technology-based approach for controlling air toxics.

Under the CAAA, technology-based control requirements are to be established to restrict the emissions of certain HAPs from certain categories of stationary sources. Only after these technical requirements are set will the EPA consider the significance of any remaining health risk.

The EPA is required to establish MACT standards for selected categories of industrial facilities that emit the listed HAP. The EPA identified the source categories since the Act passed. Table 15-4 lists some of the source categories and their subcategories that are relevant to fuel users and producers.

The MACT standards will be promulgated through successive regulations over 10 years. The first standards were to have been promulgated for 40 source categories by

November 1992, but some were delayed. The EPA did complete the Hazardous Organic NESHAP (HON), which covers many sources in the synthetic organic chemicals manufacturing industry, as well as a NESHAP for coke oven batteries. Standards have also been developed for HAP for benzene emissions. The development of these standards began before passage of the CAAA, but it has been drawn into the HAP process.

According to the EPA's final MACT promulgation schedule, which was issued on December 3, 1993, the next group of MACT standards to be set will cover mostly dry cleaning operations. Additional groups of standards will be adopted by a specified timetable, and all standards were to be promulgated by 2000. After each standard is promulgated, affected new sources must comply immediately and existing sources must achieve compliance within 3 years. In addition, MACT requirements can be triggered earlier by new major HAP sources under state/federal operating permitting programs. Lastly, if the EPA fails to meet the regulatory schedules, states must set MACT limits in the EPA's place. Should the states start developing MACT standards, they must work closely with the EPA to ensure that the state standard will not be invalidated by the EPA when it establishes its own MACT standards.

MACT Standards

The Act establishes criteria for setting technology-based MACT emissions limits. The MACT standards are based on the average emissions limitation achieved by the best performing 12% of existing sources in a source category or subcategory. If there are fewer than 30 sources in a category, the standard can be based on the average emissions limit achieved by the best performing 5 sources.

The Act also lists a number of control options that must be considered when establishing MACT, including:

• Reduction of emissions of pollutants through process changes, substitution of material, or other modifications

• Enclosure of systems or processes to eliminate emissions

• Collection, capture, or treatment of pollutants when released

• The design of equipment and operational standards

The Act provides incentives for sources to make early reductions in HAP emissions before the MACT standards are established. An existing source may obtain a 6-year extension from compliance with MACT if it achieves a

Source Categories

MACT Schedule


Petroleum and Natural Gas

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