EPA's Region 6 Office
Serving: Arkansas, Louisiana, New Mexico, Oklahoma, Texas, and 66 Tribal Nations
What are Air Toxics? EPA has developed a generic guide Taking Toxics Out of the Air (EPA-452/K-00-002) (34 pp, 950 KB, About PDF for answers to general questions concerning Air Toxics. EPA's Technology Transfer Network (TTN) is the main source of information for detailed regulatory requirements pertaining to Air Toxics. For questions specific to Applicability Determinations, Alternative Monitoring, and Compliance Assistant Projects (ADAM-CAP) in Region 6, please see key terms summarized below. When available, direct links are provided to national websites such as EPA’s TTN that provide more detail on particular topics.
What are Hazardous Air Pollutants (HAPs)? HAPs are those pollutants that are known or suspected to cause cancer or other serious health effects, such as reproductive effects or birth defects, or to cause adverse environmental effects. The degree to which a toxic air pollutant affects a person’s health depends on many factors, including the quantity of pollutant the person is exposed to, the duration and frequency of exposures, the toxicity of the chemical, and the person’s state of health and susceptibility. Currently, the Clean Air Act (CAA) identifies 187 toxic air pollutants that EPA is required to control – see TTN: Air Toxics - Pollutants & Sources for the current list of HAPs and modifications made as well as information on types of sources (i.e., major, area) for air toxics.
What are New Source Performance Standards (NSPS)? Section 111 of the CAA authorized EPA to develop technology based standards which apply to specific categories of stationary sources. These standards are referred to as New Source Performance Standards (NSPS), are found in 40 CFR Part 60 and Appendices, and regulate pollutants such as particulate matter, sulfur dioxide, carbon monoxide, nitrogen oxides, volatile organic compounds, acid mist, total reduced sulfur and fluorides. The NSPS apply to new, modified and reconstructed affected facilities in specific source categories such as manufacturers of glass, cement, rubber tires and wool fiberglass. As of 2008, there were approximately 92 NSPS. For the current status of NSPS regulations, see TTN: Select NSPS.
What are National Emission Standards for Hazardous Air Pollutants (NESHAP)? Prior to 1990, Section 112 of the CAA directed EPA to establish national emission standards to reduce emissions of HAPs. These pre-1990 NESHAPs detailed in 40 CFR Part 61 establish minimum nationwide requirements for existing and new facilities for only seven pollutants: asbestos, beryllium, mercury, vinyl chloride, benzene, arsenic, and radon/radionuclides.
The 1990 CAA Amendments outlined a new approach for reducing emissions of all HAPs, with two main components. The first component involved establishing technology-based source category standards, and the second component involved addressing any significant remaining risk after the national standards are in place. These post-1990 NESHAPs detailed in 40 CFR Part 63 establish nationwide requirements for existing and new facilities for all HAPs. Since the NESHAP Part 63 (see Volumes 9-13, separate links) require application of standards based upon implementation of Maximum Achievable Control Technology (MACT) by source category, these post-1990 NESHAPs are also referred to as MACT standards. For a list of current MACT standards by source category, see TTN: Compilation of MACT.
What is delegation? After individual NSPS and NESHAPs are promulgated, EPA may implement and enforce the requirements on a national or regional level. State and local regulatory agencies often implement and enforce similar requirements by adopting analogous regulations under state or local authority. CAA Sections 111 and 112 allow EPA to transfer primary implementation and enforcement authority for most of the federal standards to state, local, or tribal regulatory agencies. This transfer of authority is called delegation of authority. Upon delegation of a specific rule, sources must send any required notifications or reports directly to the delegated agency. NSPS and NESHAPs may be delegated to the states, but both EPA and their State/Local/Tribal partners implement and enforce the standards. See Region 6 Delegations Unraveled for more information specific to ADAM-CAP in Region 6.