IV. The Regulation of Stationary Sources|
A. Regulatory Authority
Most of the authority to regulate air pollution springs from the federal Clean Air Act. The federal Clean Air Act is a set of federal statutes that are implemented by the U.S. Environmental Protection Agency (U.S. EPA) via the Code of Federal Regulations (CFR). The original federal Clean Air Act was passed in 1970, but the act has been incrementally amended in 1973, 1977, and 1990. Currently, the federal Clean Air Act is composed of several titles, which are in turn divided into parts.
The structure of the federal Clean Air Act is shown in Table 2. Note that the table shows components of the act with corresponding parts from the CFR. The CFR serves as the body of regulations enforceable by the U.S. EPA. It is the body of regulations that implement the federal Clean Air Act statutes. From the state viewpoint, the CFR defines the criteria and constraints which the state program must meet to conform with federal requirements.
B. Delegation of Authority and Regulatory Structure
The regulation of stationary sources is conducted at three levels of government in California: federal, state, and local government. Section 110(a)(1) of the Federal Clean Air Act requires states to directly regulate both stationary and mobile sources through a state implementation plan (SIP) in such a way as to provide "for implementation, maintenance and enforcement" of national ambient air quality standards (NAAQSs). For the purposes of stationary source regulation, Sections 110(a)(2)(A), (C) and (D) are especially important in specifying responsibilities of states:
Roadmap to Permit Programs and Processes Covered in this Document1
Structure of the Federal Clean Air Act and Corresponding Parts of the Code of Federal Regulations Affecting the Permitting and Control of Emissions from Stationary Sources
The Air Resources Board is part of a larger state umbrella agency called the California Environmental Protection Agency, or Cal-EPA. The board has eleven members that govern the agency and an executive officer who serves at the board's pleasure. The mission of the board members is to "exercise their independent judgement as officers of the state on behalf of the interests of the entire state in furthering the purposes of" Division 26 of the Health and Safety Code (Air Resources). The chairman assists the governor in establishing major policy and program matters on environmental protection and communicates the governor's direction to the agency. In reality, Cal-EPA now interfaces between the chairman of the Air Resources Board and the governor, with the Cal-EPA director serving as the Secretary for Environmental Protection.
Directives in the form of air pollution statutes from the state legislature are normally added to Division 26 of the California Health and Safety Code. The Air Resources Board may adopt regulations required to implement statutes. These regulations are then incorporated in the California Code of Regulations. The board also adopts guidance in terms of model rules and regulations which districts may in turn adopt in amended or unamended form. It is now more often, however, that the board interacts with districts in the development of such model rules and regulations through a statewide air pollution control organization called CAPCOA.
State law also allows a regional air pollution control district to be formed when two or more counties to merge their air pollution regulatory functions. Currently, there are 35 districts in California, 10 of which are regional. Figure 1 shows a map of California that outlines each district. Each district has a governing board referred to as the district board. The district board is usually the board of supervisors for single county districts. Multicounty districts normally contain appointed members from county boards of supervisors and members of city councils from within the districts area of jurisdiction. The district boards further appoint the air pollution control officer and district hearing board members. The air pollution control officer is responsible for the day-to-day administration of the district. Each district also has a hearing board which is responsible for hearing appeals for temporary relief from either state visible emissions requirents or rules and regulations of the district4.
Summarizing in simple terms, the primary responsibilities for the stationary source control program and air quality planning are assigned to the local level within the three-tier structure (see Table 3). The California Air Resources Board (CARB), however, is still responsible for submitting plans and maintaining a program that is in compliance with Title 40 of the CFR, should any district fail to meet its responsibilities. As a result, CARB has an oversight role in assuring district compliance with CFR requirements, and may assume the powers of a district where the district has failed to meet federal or state requirements. In addition, the State of California adopts statutes into Division 26 of the California Health and Safety Code which provide criteria, requirements, and constraints that districts must meet in conducting their duties and maintaining their programs. District programs are documented in district rules and regulations as well as local air quality. The air quality plans are adopted by the districts in order to meet state and federal requirements. Those portions of the plans which are federally required are then approved by CARB and subsequently the U.S. EPA before becoming part of the federally-required State Implementation Plan (SIP). The U.S. EPA does not have to fully approve or reject required plans, measures, and rules. Partial or conditional approval may also be granted.
District requirements for stationary sources primarily fit into three categories. The first category of requirements are rules which every source or every source in a certain category of sources must meet. We often refer to such rules as prohibitory rules. They apply whether or not a source is new or existing. A second category of rules applied to stationary sources are permitting rules for the siting and operating of new and modified stationary sources. These rules can be divided into:
California Air Pollution Control and Air Quality Management Districts
Regulatory Matrix for Air Pollution Control in California
C. Exposure Tolerance and Standards
In general, an air pollutant which has an acceptable human exposure level can be assigned an ambient air quality standard. These standards are developed with the aid of studies which provide health-based criteria for the standard. As a result, pollutants having air quality standards are referred to as criteria pollutants. On the other hand, toxic air contaminants (TACs) are not generally recognized as having acceptable human- exposure levels.6 These include carcinogens, mutagens, and teratogens.
There is a difference in strategy to achieve acceptable air quality as a result of the difference in the type of harm caused by criteria pollutants and TACs. Acceptable criteria for unharmful exposure to criteria pollutants may be stated in terms of air pollutant concentrations. In contrast, the acceptable level of exposure to TACs (of which federal HAPs are a subset) is typically based on dosages for carcinogens that are correlated with cancer risk. When combined with source and receptor exposure configuration, the effect of carcinogens can be modeled and expressed as excess cancers (above baseline). It is important to note that the level of excess cancers may depend on not only the concentration and toxicity of the pollutant, but the specific areal distribution of sensitive receptors around the source in terms of human exposure. Furthermore, noncarcinogenic effects resulting from TAC exposure can be evaluated using acute and chronic reference exposure levels.
National and California ambient air quality standards for criteria pollutants are listed in Table 4. Note that federal standards are divided into primary and secondary standards. Primary standards are air quality levels which are necessary to maintain an adequate margin of safety for the protection of public health.
Federal and California Ambient Air Quality Standards (Reference: ARB Fact Sheet 39)
Secondary standards are established at air quality levels necessary to protect public welfare from the adverse effects of criteria pollutants. Such adverse effects may include damage to crops, building materials, and the environment. In contrast federal standards, state standards are not divided into primary and secondary standards. However, they are usually more stringent than national standards.
The federal and state air quality programs are primarily aimed at protecting citizens and secondarily property and the general environment from air pollution. In further presenting the statutory and regulatory relationships, the programs for criteria pollutants and TACs will be kept separate both to simplify the relationships and because the regulations of the two categories of pollutants are different.
Figures 2 and 3 are regulatory road maps that can help to facilitate the reader's understanding of the interrelationships between the federal, state, and local air quality laws, regulations, and programs in California. In order to more easily understand the following discussion on programs, it is to one's benefit to closely inspect Figures 2 and 3 before proceeding and to refer back to these figures periodically while reading through the text. While reading and interpreting these regulatory roadmaps, keep in mind the relationships between statutes, programs, and regulations (see the left column in the Figures). At the federal level, statutes are passed by Congress that provide the U.S. EPA with the authority to establish programs and publish regulations initiate requirements of the statutes. From the state perspective, the state has to design programs to carry out requirements mandated by federal regulations and any applicable state statutes. State assistance is then provided to local districts in carrying out federal and state requirements at the local level through local programs and/or local rules and regulations. As a result, there is a web of relationships between statutes, programs, and regulations.
D. Federal Regulation of Criteria Pollutant Emissions from Stationary Sources
The stringency of both prohibitory and permitting rules depends on the type of pollutants emitted and the existing air quality problem. The federal Clean Air Act is structured to deal with air quality problems based on their severity. With regard to pollutants with national ambient air quality standards (i.e., criteria pollutants), it provides for more stringent control of criteria-pollutant emissions that potentially contribute to a violation of a national ambient air quality standard than those which do not.7 Such emission control covers both those pollutants that contribute with direct emissions (i.e., primary pollutant emissions) and emissions of pollutants which participate in the secondary formation of criteria pollutants (i.e., recognized precursor emissions).8 For instance, PM10 can be directly emitted into the atmosphere as a primary pollutant. In addition, it can be formed phere largely from pollutants emitted by gases, such as oxides of nitrogen and oxides of sulfur, chemically converted to solid forms or absorbed onto ambient aerosols. Aerosol formed by chemical conversion or absorption onto existing aerosols are referred to as secondary PM10. Commonly, reactive organic compounds, oxides of nitrogen, and oxides of sulfur are considered precursors of PM10.
To distinguish between areas with different levels of air quality problems, air quality jurisdictions are classified with respect to their compliance status for each national ambient air quality standard. In other words, for any given air quality jurisdiction in the United States, there are status designations for each criteria pollutant. For instance, areas where the carbon monoxide standard is violated are designated carbon monoxide nonattainment areas. On the other hand, if sufficient air quality monitoring indicated the area was in compliance with the carbon monoxide air quality standard, the area would be designated a carbon monoxide attainment area. If there are no violations and there is insufficient air quality monitoring data to make a determination, the area would be assigned unclassified status. It is important to note that the same area that is classified as attainment for carbon monoxide may be nonattainment for some other criteria such as ozone.
Federal ozone nonattainment areas are further classified as marginal, moderate, serious, severe, or extreme based on the extent to which a national ambient air quality standard is violated.9 Authority to regulate nonattainment pollutants is largely provided by Part D of Title I of the federal Clean Air Act (Plan Requirements for Nonattainment Areas). Authority to regulate an area designated as attainment or unclassified for a pollutant is largely provided by Part C of Title I (Prevention of Significant Deterioration of Air Quality). Part D generally requires that air quality plans achieve sufficient emission reductions to bring about compliance with any violated national ambient air quality standards within a given air quality jurisdiction. Such plans are part of and augment the SIP components otherwise required by Section 110 of the Clean Air Act.
E. Stationary Source Strategies in Nonattainment Area Plans
In terms of stationary source control for nonattainment pollutants, emissions are reduced through the application of technically- and economically-reasonable retrofit control technologies on existing sources. Such technology is referred to as reasonably available control technology (RACT). Measures incorporating RACT are referred to as reasonably available control measures (RACMs). To simultaneously prevent counteracting growth of the emission inventory due to siting new sources or modifying existing sources, new source review (NSR) rules are applied to new major sources and major modifications associated with significant increases in criteria-pollutant emissions. In California, most districts extend NSR requirements to some minor sources.
The U.S. EPA documents the regulatory application of RACT as RACMs with control technology guidelines (CTGs). A similar process of adapting potential control technologies for application in control measures was formerly conducted in California. In the late 1970's, CARB wrote guidelines in the form of model rules for control measures to be used in California air quality plans. This process was later replaced by a suggested control measure (SCM) process. The SCM process was a joint effort between CARB and the California Air Pollution Control Officers Association (CAPCOA). Districts may adopt these measures, often with some modifications, and then incorporate them into their respective local air quality plans. The plans are then submitted to ARB and subsequently the U.S. EPA for approval and incorporation into the SIP.
F. Federal Programs for Preconstruction Permits
The federal Clean Air Act has several programs that regulate the siting of new sources and modification of existing stationary sources. The most important of these programs is NSR and prevention of significant deterioration (PSD). NSR applies to sources emitting nonattainment pollutants. PSD applies to sources emitting attainment pollutants. Since it is easily possible that a given stationary source can emit both classes of pollutants, i.e., pollutants for which an area is classified for either attainment or nonattainment, the NSR and PSD rules may apply simultaneously to the same source for different pollutants.10 The requirements of these programs apply to major sources and major modifications 11, although the definitions of "major source" and "major modification" differ between the two programs. The requirements of NSR or PSD vary depending on the particular local or state sit especially in California.
In most cases, major sources in nonattainment areas are those sources over 100 tons/year of any criteria pollutant, but may spread down to 10 tons/year depending on severity of a nonattainment area (see definition in Table 5). NSR would apply to these sources. A similar emission threshold level for attainment areas is 250 tons per year of an attainment pollutant, with exception of 28 listed sources. These later 28 sources would be subject to PSD permitting requirements at 100 tons per year. More specifically, Table 5 shows the various definitions of "major source" used in the federal programs not only for PSD and NSR, but also HAPs and Title V. Stationary sources smaller than major sources are referred to as minor sources. As mentioned earlier, NSR requirements commonly extend to minor sources in California. Most California districts use relatively lower emission levels than those used at the federal level for triggering local NSR requireme As alluded to earlier, the NSR program addresses siting requirements for sources which directly emit criteria pollutants (or precursors to criteria pollutants) and have the potential to aggrevate air quality in a local air quality jurisdiction in violation of a national ambient air quality standard. As far as federal requirements go, this program only applies to nonattainment pollutants and specified precursors. NSR rules are intended to require appropriate levels of emission control and mitigation of any increase in emissions that would hinder progress towards compliance of the air quality jurisdiction with national ambient air quality standards.
For the purposes of federal NSR requirements, the appropriately stringent emission control for sources emitting nonattainment pollutants and their precursors is considered LAER. One can find the definition of LAER in the federal Clean Air Act12, and it will be discussed later in detail. Other requirements may also include an air quality analysis to determine if a standard will be violated due to a permitting action, and, if triggered, mitigation of the emission increases with a resulting positive net air quality benefit.
In terms of mitigation requirements for nonattainment pollutants, NSR may require that significant emission increases from any given major source be mitigated by decreases from other sources in the area of impact.
Major Source Definitions for Various Programs of the Federal Clean Air Act13
When required, mitigation is usually provided in the form of emission reductions either from units already at the facility (if the facility is being modified) or other facilities within the district. If the emission reductions are contemporaneous14 with the emission increases, emission reductions may be credited from one facility to the other.15
Emission reductions from the modification of a stationary source can be banked if the air quality jurisdiction has a banking rule. Such rules preserve emission reductions for use as credit against subsequent emission increases. They also provide for a more formal review of emission reductions and include criteria for determining what is a creditable emission reduction.
If an air quality jurisdiction has an emission banking rule, emission reductions may have to meet more stringent requirements imposed by the emission banking rule.16 In most California banking rules, for example, emission reduction credits would have to be real, quantifiable, permanent (or at least be valid for the life of the emission increase), surplus, enforceable, and, sometimes, adjusted to a value that coincides with an emission rate (i.e., pounds per day, pounds per calendar quarter, or tons per year).17 In addition, the ratio of emission reductions to new emissions (i.e., the emission offset ratio) may be offset at a ratio greater than 1:1.
One may ask how an NSR rule prevents emission growth if only major sources are required to offset emission increases. New non-major sources, i.e., minor sources, can be responsible for significant increases in a district's emissions inventory. The theoretical approach to this problem was to require more than 1:1 offset ratios for major sources. The thought was that the additional offsets would provide for mitigation of minor sources. In fact, the results of such a strategy were never realized, at least in California. Since there is no abundance of potential offset sources, relatively few sources were built large enough to trigger offsets, or they were built with very efficient control technologies that prevented sources from triggering NSR emission offset requirements. The result is that NSR rules tend to protect against excessive air quality declines, but do not live up to their billing as a maintenance measure. Later attempts at the state l ire offsets for all stationary sources in areas having serious air quality problems may have seemed unacceptably stringent to the regulated community, resulting in attempts to relax the no-net-increase requirements.
In attainment areas, the concern goes beyond protecting against new violations of a national ambient air quality standard. The PSD program is designed to prevent significant deterioration of air quality due to the siting of new or modification of existing sources in areas which comply with national ambient air quality standards. The federal Clean Air Act provides for establishing baseline air quality18 in any PSD area where a new or modified facility is to be sited. The emissions of a given criteria pollutant from a new or modified facility are not to degrade the air quality by more than certain air quality increments above air pollutant concentrations existing on the date of PSD baseline air quality19 or up to ambient concentrations corresponding to the national ambient air quality standards, whichever is more stringent. The size of the air quality increment depends on the classifi e area and air pollutant. At this time, however, not all criteria pollutants have listed air quality increments. Only sulfur dioxide, nitrogen dioxide, and particulate matter currently have listed air quality increments. If all goes as planned, there may also be a new increment for PM10 in the future.
All PSD areas were initially established as Class II areas, except areas of scenic value, such as international parks, national parks which exceed 6,000 acres, and national wilderness areas plus national memorial parks which exceed 5,000 acres. These later areas were assigned Class I status, which has smaller air quality increments to protect their natural state (see Figure 4, but note that Figure 4 only contains the original California Class I areas). If jurisdictions with Class II status wish to not comply with Class II air quality increment, they may redesignate to Class III, which has no increments. Exceptions are any of the following which exceed 10,000 acres: national monuments, national primitive areas, national preserves, national recreation areas, national wild and scenic rivers, national wildlife refuges, national lakeshores, national seashores, and national parks and wilderness areas established after the date of enactment of the CAA. tions may redesignate only to Class I or II.
Table 6 provides a summary of area designations and the applicability of permitting programs and requirements. When inspecting Table 6, it is important to also remember that the NSR, PSD, and Title V programs all have different definitions of the term "stationary source" (see Table 5).
When siting a major source or conducting a major modification of an existing major source that emits an attainment or unclassified pollutant (i.e., a PSD pollutant), one must obtain a PSD permit. In addition to addressing emissions of criteria pollutants for national ambient air quality standards which are not violated in the air quality jurisdiction, the program also addresses several "noncriteria pollutants."(20) PSD permits may be issued by the U.S. EPA. However, in some cases, a state or local air quality agency will have an SIP-approved PSD rule or the U.S. EPA may have delegated such permitting authority to such an agency. In such cases, the siting or modification of pollutant-emitting facilities is conducted in accordance with the requirements of a state agency or district rule. Tasks conducted in the permitting effort include establishment of the emission increase, the air quality baseline, control techno ments; assessment of the air quality impact on standards and air quality related values; assessment of compliance with increments in any nearby Class I areas, and, if needed, mitigation of the air quality impact. Establishment of the air quality baseline may require monitoring prior to submittal of an application.
Federal Area Designations for Criteria Pollutants and Corresponding Federal Stationary Source Requirements
In addition to the above requirement for NSR and PSD, some requirements will apply no matter what the status of the criteria pollutant. For instance, NSPS will apply to certain major sources. For districts which have adopted NSPS requirements in the SIP or received delegation for the NSPS program, NSPS requirements are usually incorporated into district prohibitory rules by reference.
G. Federal Operating Permit Requirements
Up until 1990, the federal Clean Air Act did not address the need for an operating permit program. Finally, the 1990 Clean Air Act Amendments added an operating permits program under Title V. It is interesting to note that all the preconstruction permit programs (i.e., NSR, and PSD, and Section 112(g)) are under Title I and that NSR and PSD are an SIP requirement if districts receive delegation from the U.S. EPA.21 In contrast, Title V is not to be incorporated into the SIP. Also, unlike federal preconstruction permit programs, the Title V operating permit program addresses all federally-regulated air pollutants, including HAPs and criteria pollutants.
There are several reasons for the adoption of Title V. Some are much more obvious than others. But underlying much of the U.S. EPA effort is an endeavor to gain greater influence in the permitting process and enforceability of conditions required by federal regulations. The six main reasons for adopting the program appear to be to:
Title V generally does not require additional emission controls. Instead, much of Title V is directed at providing a mechanism for enforcing existing federal requirements. Additional Title V requirements relate largely to permitting procedures, and requirements for monitoring, recordkeeping, and reporting. Its requirements affect existing major sources and some nonmajor sources as well as new and modified major sources. Existing sources subject to Title V must be reviewed for Title V compliance and issued a permit within three years of U.S. EPA approval of local Title V rules. Also, a permit review is required every five years or when a facility modifies. Unfortunately, Title V and its corresponding regulation, 40 CFR Part 70, are sometimes difficult to interpret. Title V program requirements have been challenged by industry and environmentalist, and the U.S. EPA proposes revisions to 40 CFR Part 70.
H. Federal Regulation of HAPs Emissions from Stationary Sources
Along with criteria pollutant emissions, the federal Clean Air Act provides authority to regulate HAPs, largely through Section 112 in Part A of Title I. Federal regulation of HAPs is mostly through NESHAPs. NESHAPs promulgated before 1990 are risk-based restrictions on the emission of HAPs. These NESHAPs are still in effect, but the federal structure for regulating HAPs has significantly changed with the passage of the 1990 amendments to the federal Clean Air Act. Both new and existing sources are now subject to a set of category-specific, technology-based NESHAPs, often called maximum achievable control technology (MACT) standards.22 Similar but less stringent requirements aimed more at smaller, more dispersed sources are referred to as generally available control technology (GACT).23
New and modified source requirements are in the NESHAP general provisions and MACT standards. Section 112 also requires the U.S. EPA to develop requirements for new and modified major sources of HAPs that are not yet subject to MACT standards. New regulations promulgated in the CFR pursuant to Section 112(g) now require that no major source of HAPs can be constructed24 or reconstructed25 after June 29, 1998 without MACT, unless the control requirement is at least as stringent or more stringent as the best controlled similar source. Furthermore, California districts will have to adopt and implement programs that meet the requirements of this new regulation. A district that does not have a program in place by June 29, 1998 may, for a limited one-year period, have the U.S. EPA approve the district's case-by-case MACT determinations or request that the U.S. EPA conduct case-by-case MACT ons for the district.
1. Acronyms used in this table are included in the list of acronyms near the front of the document.
2. Requirements for areas which comply with national ambient air quality standards.
3. Requirements for air quality plans in areas which violate a national ambient air quality standard.
4. But not from the permit conditions of a preconstruction permit.
5. Some rules would govern these activities for the facility rather than a unit. This is especially true for rules closely patterned after federal regulations.
6. According to Section 39655 of the California Health and Safety Code, a toxic air contaminant is " an air pollutant which may cause or contribute to an increase in mortality or in serious illness, or which may pose present or potential hazard to human health." Section 39655 also incorporates all federal hazardous air pollutants (HAPs) as toxic air contaminants by reference.
7. In general, criteria pollutants are those pollutants for which there is a national ambient air quality standard. In California, the list of criteria pollutants is expanded to also include pollutants regulated by state ambient air quality standards.
8. Precursors are primary emissions that contribute to the formation of secondary pollutants, i.e., a pollutant formed in the atmosphere. In theory, a pollutant could have many precursors and it may be debatable as to what primary emissions contribute to the formation of a secondary pollutant. Even the degree of contribution may be debatable. As a result, it is necessary to legally define precursor relationships in regulations. In California, new source review rules usually list such relationships in the definition sections of rules under the term "precursor."
9. For classification criteria, see Table 1 in Section 181 of the Federal Clean Air Act. Nonattainment area plan requirements can be found in Section 182.
10. In some cases, a district NSR may be written to apply to all pollutants emitted from the source. As a result, emissions of attainment pollutants may be regulated by both NSR and PSD rules. In addition, a pollutant which is a precursor to a criteria pollutant and is simultaneously regulated directly as primary pollutant by another standard may be subject to simultaneous review by both programs. This is because the air quality jurisdiction may be attainment for one of the criteria pollutants while being nonattainment for the other. An example would be oxides of sulfur which are regulated as a primary pollutant with a sulfur dioxide standard and as a precursor to PM10.
11. The terms "major source" and "major modification" apply at the facility level. In California, federal requirements have been adapted to apply at the unit level, a unit being a distinguishable entity within the stationary source usually referred to as "any article, machine, equipment or other contrivance or multi-component system, the use of which may cause the issuance of air contaminants, or which may eliminate, reduce or control the issuance of air contaminants." This definition is similar to what federal regulations refer to as an emissions unit.
12. Often called best available control technology in California. Most California districts do not use the term "lowest achievable emission rate," but have a best available control technology definition that is similar, if not equivalent, to the federal definition of lowest achievable emission rate.
13. Note that some provisions in these definitions have been ignored since they are very lengthy and contribute mostly as exceptions to general rules.
14. Or, to different degrees depending on district rules, before the increase due to the siting of the source to be offset.
15. That is, the reductions will occur on or before the time when the new emissions units begin operation, or within an allowed time interval as specified in the NSR rule.
16. However, the emission reductions used to offset new emissions will not have to be contemporaneous with the emission increase to be offset. That is, a banking rule allows emission reduction credits to be banked for use in offseting a future emission increase.
17. Simple, informal explanations of emission reduction credit criteria are as follows:
18. The baseline air quality is defined as the air quality for a criteria pollutant being reviewed under PSD that existed on August 7, 1977, i.e., the adoption date of the 1977 federal Clean Air Act Amendments. If the air quality at that time can not be established with historic air quality monitoring, a monitoring study of current air quality is usually required before an applicant submit an application for a PSD permit.
19. January 6, 1975 for oxides of sulfur and particulate matter, or February 3, 1988 for oxides of nitrogen. The air quality existing on this date is often referred to as the air quality baseline.
20. In addition to criteria pollutants, the emissions of several other air pollutants are also regulated by PSD rules. These include elemental lead, fluorides, sulfuric acid mist, total reduced sulfur compounds, hydrogen sulfide, chlorofluorocarbon, halons, acid gases, metals, furans, and dioxins from municipal waste combustors.
21. District Section 112(g) programs will not be included in the SIP. Major sources of HAPs sited after June 29, 1998 will be required to reviewed under a Section 112(g) program. Much of the Section 112 program for both new and existing sources will be implemented via Title V operating permits.
22. Actually, the term NESHAP refers to all emission standards promulgated under Section 112 of Title I. But often, HAP emission standards promulgated before July 21, 1992 are referred to as NESHAPs, while those promulgated after that date are often referred to as MACT standards.
23. In an informal way, new-source MACT is similar to BACT, and GACT and existing-source MACT are similar to RACT. That is, they are applied on a category or source basis and can be revised to be more stringent when new control technologies become available. Unlike BACT and LAER, MACT is defined for existing as well as new and modified sources.
24. In this regulatory context, a source undergoing construction can either be a new source or an addition at an existing facility that would constitute a major source of HAPs by itself.
25. In this case, if a modified source has a fixed capital cost exceeding 50 percent of the fixed capital cost to construct, it is considered a reconstructed source.