![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Module 7: Regulatory Requirements - Title III: Hazardous Air Pollutants
Lesson Material
Practice Problems
Objectives
- Identify the type of pollutants covered by NESHAP regulations.
- Describe the objective of MACT standards.
Prior to the 1990 Clean Air Act Amendments (1990 CAAA), the control of hazardous air pollutants (HAPs) was based on the National Emission Standards for Hazardous Air Pollutants (NESHAPs). These regulations involved "noncriteria" pollutants - those not covered by the National Ambient Air Quality Standards (NAAQS) because the emission sources were localized. EPA promulgated especially stringent emission limitations for these pollutants because they were known to be capable of increasing mortality rates at high concentrations and increasing the incidence of irreversible or incapacitating reversible illnesses at low concentrations. During the time period from 1970 when the NESHAP program was initiated until 1990, a total of seven pollutants were designated as hazardous and regulated in accordance with these requirements. They are as follows:
- Beryllium
- Asbestos
- Mercury
- Vinyl chloride
- Benzene (fugitive emissions)
- Radionuclides
- Inorganic arsenic
The NESHAP regulations were oriented toward the major source categories with significant emission rates. The regulations were prepared in a variety of forms, including mass emission limitations, design standards, and work practice standards. These regulations apply to both existing and new sources.
The 1990 CAAA have greatly expanded programs directed at hazardous air pollutants (often-termed air toxics). Title III of the amended Clean Air Act initially included a list of 189 compounds or groups of compounds that were designated as hazardous. This list included all seven pollutants previously regulated under the NESHAP regulations. Provisions are included to allow EPA to add and delete pollutants from this list, as more information becomes available. One pollutant has been dropped from the original list of 189; therefore, 188 compounds or group of compounds are currently regulated under Title III.
The U.S. EPA is obligated to compile a list of the major source categories and area source categories that emit significant amounts of the pollutants on this list. A major source is defined as any facility that has the potential-to-emit 10 tons per year of any one of the materials or 25 tons per year of any combination of the materials. The 10-ton per year value is equivalent to 2.2 pounds per hour (assuming a 24-hour per day, 365 day per year operation). Accordingly, the requirements pertaining to hazardous air pollutants are intended to affect even relatively small stationary sources.
The emission controls to be implemented by Section 112 are termed maximum achievable control technology (MACT). The purpose of the MACT standards is to establish NESHAPs that require " the maximum degree of reduction in emissions of the hazardous air pollutants subject to this section (including a prohibition on such emissions, where achievable) that the Administrator, taking into consideration the cost of achieving such emission reduction, and any non-air quality health and environmental impacts and energy requirements, determines is achievable for new or existing sources in the category or subcategory to which such emissions applies…". As with BACT (Best Achievable Control Technology), these new standards are meant to be practicable because cost considerations can be taken into account in the determination of the emission limitations. EPA is in the process of implementing emission limits that are no higher than the average emission standards achieved by the best performing 12 percent of sources in each category specified in Section 112 (or the top 5 facilities if the category contains less than 30 sources).
The regulations under Section 112(g) require the application of controls for construction of new facilities and reconstruction of large sources of toxic air emissions at existing facilities. This is a transitional provision until most MACT standards are in place.
The previously promulgated NESHAP regulations applicable to the source categories remain in effect. However, these regulations and any newly adopted regulations based on the 1990 CAAA, will be subject to periodic EPA review and updating.
Practice Problems
Title III - Hazardous Air Pollutants
- Instructions:
- Complete the Practice Problems before proceeding to the next lesson. Click on the button below.