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Section A. Clean Air Act Requirements

Law: Federal Clean Air Act (amended 1990)

The Clean Air Act (CAA), with its 1990 amendments, sets the framework for air pollution control as it affects the electronics industry. This framework has several elements. Several portions of Title I of the CAA address requirements for the attainment and maintenance of National Ambient Air Quality Standards (NAAQS). Section A.1 discusses how the implementation of Title I of the CAA may affect the electronics industry.

Section 112 of the CAA covers emissions of hazardous substances. For a wide variety of such substances, Congress directed the EPA to base its limits on emissions and technologies rather than on ambient air quality per Section A.2 discusses how controls on hazardous air pollutants may affect the semiconductor industry.

The 1990 amendments to the CAA provide a new mechanism for implementing both the National Ambient Air Quality Standards and the Act's hazardous substance limitations. This new mechanism is the permit, which would be required of major sources of (1) pollutants affecting ambient air quality, (2) hazardous air pollutants, and (3) new sources. Permits are discussed in Section A.3 of this report.

Finally, Title VI of the Clean Air Act addresses ozone-depleting chemicals. Several solvents used in the computer industry are affected by this law. These requirements are discussed in Section A.4 of this report.


EPA's National Ambient Air Quality Standards (NAAQS) establish levels of air quality that are to be applied uniformly throughout regions in the United States. An air quality control region is classified as a "nonattainment" area if a NAAQS is violated anywhere in the region. (In the case of ozone, a violation occurs if the 4th highest reading over any 24-hour period in the past 3 years exceeds the NAAQS for ozone.) Two types of NAAQS are set:

    (1)Primary standards that define the level of air quality necessary to prevent any adverse impact on human health, and

    (2)Secondary standards that define the level of air quality necessary to protect the public welfare from any known or anticipated adverse effects of a pollutant.

These standards recognize that the severity of the adverse health effects associated with exposure often depends on the duration of exposure. Accordingly, "short-term" standards set limits for a 1-hour, an 8-hour, or a 24-hour period, while "long-term" standards are established on an annual basis.

The EPA has set National Ambient Air Quality Standards for the six pollutants shown in Exhibit 1. These standards are used as a foundation for the regulatory framework discussed in this section. Of the six, only the NAAQS for ozone is likely to have a significant impact on the electronics industry. Electronics manufacturing facilities are not, of course, major sources of ozone per se; however, they are sources of emissions of volatile organic compounds (VOCs),the precursors of ozone. Thus, although there is a NAAQS for ozone, the relevant emissions for monitoring purposes are VOCs.

National Ambient Air Quality Standards for Criteria Pollutants (As of July 1, 1991)

Pollutant Primary Standards
(Protective of Health)2
Ozone 0.120 ppm (235 g/m3
(1-hour average)
Carbon Monoxide 9 ppm (10 mg/m3)
(8-hour average)
35 ppm (40 mg/m3)
(1-hour average)
Particulate Matter (PM-10) 150 g/m3
(24-hour average)
50 g/m3
(annual arithmetic mean)
Sulfur Dioxide 0.140 ppm (365 g/m3)
(24-hour average)
0.03 ppm (80 g/m3
(annual arithmetic mean)
Nitrogen Dioxide 0.053 ppm (100 g/m3)
(annual arithmetic mean)
Lead 1.5 g/m3 (arithmetic mean averaged quarterly)

A.1.1 New Sources of Volatile Organic Compounds (VOC) Emissions

In both attainment and nonattainment areas, whenever new plants are built or emissions from existing sources increase as a result of expansion, a New Source Review (NSR) is triggered. Special rules apply in attainment areas. These are called Prevention of Significant Deterioration (PSD) requirements and include the following:

  • Installation of Best Available Control Technology (BACT);

  • A detailed air quality analysis showing that there will be no violation of PSD "increments";

  • Prediction of future air quality standards; and

  • Possible monitoring of air quality for one year prior to the issuance of the permit.
Restrictions in nonattainment areas are more severe. The principal requirements of NSR in nonattainment areas are:
  • Installation of Lowest Achievable Emission Rate (LAER) technology;

  • Provision for "offsets" (see Exhibit 2) representing emission reductions that must be made from other sources; and

  • Demonstration of standard attainment through the undertaking of an air quality analysis.

Major Source Definitions and Offset Ratios in Ozone Nonattainment Areas

Category Size of Major Source5
(tons/year of vocs)
Offset Ratios
Marginal 100 1.1:1
Moderate 100 1.15:1
Serious 50 1.2:1
Sever 25 1.3:1
Extreme 10 1.5:1

A.1.2 Existing Sources of VOC Emissions

A.1.2.1 Ozone non-attainment areas

The "design value" shown in column 3 of Exhibit 3 is the 4th highest reading taken over any 24-hour period in a nonattainment area. Based on this figure, a nonattainment area is classified as Marginal, Moderate, Serious, Severe, or Extreme. As shown in this exhibit, attainment deadlines are based on a sliding scale that reflects the severity of the pollution.

Classification of Ozone Nonattainment Areas

Classification Deadline to Attain
(from November 15, 1990)
Design Value (ppm)
Marginal 13 Years 0.121 - 0.138
Moderate 6 Years 0.138 - 1.160
Serious 9 Years 0.160 - 0.180
Severe 15 Years 0.180 - 0.190
17 Years 0.190 - 0.280
Extreme 20 Years Above 0.280

Areas that are likely to be classified as Extreme, Severe, or Serious as of late-1990 are presented in Exhibit 4.

Ozone Nonattainment Areas

Extreme (1 area)
Los Angeles-Anaheim-Riverside, CA
Serious (16 areas)
Atlanta, GA
Bakersfield, CA
Baton Rouge, LA
Beaumont-Port Arthur, TX
Boston, MA
El Paso, TX
Fresno, CA
Hartford, CT
Huntington-Ashland, WV-KY-OH
Parkersburg-Marietta, WV-OH
Portsmouth-Dover-Rochester, NH-ME
Providence, RI
Sacramento, CA
Sheboygan, WI
Springfield, MA
Washington, DC-MD-VA
Sever (8 areas)
Baltimore, MD
Chicago, IL-IN-WI
Houston-Galveston-Brazoria, TX
Milwaukee-Racine, WI
Muskegon, MI
New York, NY-NJ-CT
Philadelphia, PA-NJ-DE
San Diego, CA

A source defined as "major" must install Reasonably Available Control Technology (RACT) as prescribed in the applicable State Implementation Plan (SIP). A major source is defined both by the size of the source's emissions and the category of the nonattainment area. These conditions are presented in Exhibit 5. In addition, if a firm has the potential to emit more than 100 tons per year (TPY), it is also considered to be a major source. Potential to emit means the maximum capacity of a stationary source to emit a pollutant under its physical and operational design.

A determination of the necessary RACT requirements is made on the basis of a case-by-case review of each facility. In an attempt to issue uniform guidelines, the EPA has begun to issue Control Technique Guidance (CTGs) for industrial categories. The following Control Technique Guidances may apply to the semiconductor industry:

  • Miscellaneous Metal Parts and Products
  • Plastic Parts (expected 1993)
  • Alternative Control Technology (ACT) for Solvent Cleaning
To the extent that an computer industry source is covered by any of EPA's CTGs, it may be covered by a State Implementation Plan (SIP) RACT rule even if it is not a major source.

Each State is required to develop a SIP for all nonattainment areas. SIPs contain a wide range of requirements that are designed to decrease ozone levels by controlling VOC emissions.

Existing Source Reasonably Available Control Technology (RACT)
Requirements for Each Ozone Nonattainment Category

Category of Nonattainment Area Size of VOC or NOx
Sources Affected
Extreme 10
Severe 25
Serious 50
Moderate and Marginal 100


The National Ambient Air Quality Standards apply to a small number of the most common pollutants. Additional controls that directly restrict the emission of 189 hazardous air pollutants are established in Section 112 of the Clean Air Act. EPA is authorized to establish Maximum Achievable Control Technology (MACT) standards for source categories that emit at least one of the pollutants on the list. Chemicals listed in Part 112 of the Clean Air Act that are used in semiconductor manufacturing, semiconductor packaging, printed wiring board manufacturing, and display manufacturing are shown in Exhibits 6 - 9.

Chemicals Used in Semiconductor Manufacturing That are Scheduled for Maximum Achievable Control Technology (MACT) Standards

Hazardous Air Pollutant
Antimony compounds Hydrochloric acid
Arsenic compounds Hydrofluoric acid
Arsine Methanol
Carbon tetrachloride Methyl isobutyl ketone
Catechol Nickel compounds
Chlorine Phosphine
Chromium compounds Phosphorus
Ethyl acrylate 1,1,1-Trichloroethane
Ethyl benzene Trichloroethylene
Ethylene glycol Xylene

EXHIBIT 7. Chemicals Used in Semiconductor Packaging That are Scheduled for Maximum Achievable Control Technology (MACT) Standards

Hazardous Air Pollutant
Chlorine Methanol
Chromium Methylene chloride
Ethyl benzene Nickel compounds
Ethylene glycol Toluene
Hydrochloric acid 1,1,1 Tricholoroethane
Hydrofluoric acid Xylene
Lead compounds

EXHIBIT 8. Chemicals Used in Printed Wiring Board Manufacturing That are Scheduled for Maximum Achievable Control Technology (MACT) Standards

Hazardous Air Pollutant
Chlorine Lead compounds
Dimethylformamide Methylene chloride
Formaldehyde Nickel compounds
Hydrochloric acid Perchloroethylene
Hydrofluoric acid 1,1,1-Trichloroethane
Ethylene glycol

Chemicals Used in Display Manufacturing That are Scheduled for Maximum Achievable Control Technology (MACT) Standards

Hazardous Air Pollutant
Lead compounds Trichloroethylene

In addition, EPA is in the process of identifying categories of industrial facilities that emit substantial quantities of any of these 189 pollutants. Regulations that will apply specifically to the semiconductor industry are expected in 1997. These standards, which will require the maximum degree of pollution reduction, can be imposed on listed sources and may require a wide range of control measures, including:

  • Installation of control equipment;
  • Process changes;
  • Material substitution;
  • Work practice changes; and
  • Operator training or certification.
These measures are expected to achieve a 75- to 90-percent emission reduction below current levels.

A source will receive a 6-year extension in the compliance date for a MACT standard if it achieves a 90-percent reduction in its air toxic emissions prior to the date on which the MACT standard is proposed for its industry category. There is no requirement to notify EPA before issuance of the standard; however, the demonstration of emissions reduction must be made before the standard is proposed. A source should submit its demonstration either along with its Title V permit application or as a permit modification. EPA has issued regulations specifying how the demonstration must be made (40 CFR Part 63, Subpart D).

A.3 PERMITS (40 CFR 70)

The CAA and its implementing regulations (at 40 CFR 70) define the minimum standards and procedures required for State operating permit programs. The permit system is a new approach established by the Amendments that is designed to define each source's requirements and to facilitate enforcement. In addition, permit fees will generate revenue to fund implementation of the program.

Any facility defined as a "major source" is required to secure a permit. Part 70.2 defines a source as a single point from which emissions are released or as an entire industrial facility that is under the control of the same person(s), and a major source is defined as any source that emits or has the potential to emit:

  • 10 TPY or more of any hazardous air pollutant;
  • 25 TPY or more of any combination of hazardous air pollutants; or
  • 100 TPY of any air pollutant.
For ozone nonattainment areas, major sources are defined as sources with the potential to emit:
  • 100 TPY or more of volatile organic compounds (VOCs) in areas defined as marginal or moderate;
  • 50 TPY or more of VOCs in areas classified as serious;
  • 25 TPY or more of VOCs in areas classified as severe; and
  • 10 TPY or more of VOCs in areas classified as extreme.
In addition to major sources, all sources that are required to undergo New Source Review, are subject to New Source Performance Standards, or are identified by Federal or State regulations, must obtain a permit.

By November 15, 1993, each State must submit a design for an operating permit program to the EPA for approval. The EPA must either approve or disapprove the State's program within one year after submission. Once approved, the State program goes into effect.

Major sources, as well as the other sources identified above, must submit their permit applications to the State within one year of approval of the State program. (This will take place near the end of 1995). Once a source submits an application, it may continue to operate until the permit is issued. When issued, the permit will include all air requirements applicable to the facility. Among these are compliance schedules, emissions monitoring, emergency provisions, self-reporting responsibilities, and emissions limitations. Five years is the maximum permit term.

As established in 40 CFR 70, the States are required to develop fee schedules to ensure the collection and retention of revenues sufficient to cover permit program costs. The CAA sets a presumptive minimum annual fee of $25 per ton for all regulated pollutants (except carbon monoxide), but States can set higher or lower fees so long as they collect sufficient revenues to cover program costs.


The CAA Amendments provide for a phase-out of the production and consumption of chlorofluorocarbons (CFCs) and other chemicals that are causing the destruction of the stratospheric ozone layer. The requirements apply to any individual, corporate, or government entity that produces, transforms, imports, or exports these controlled substances.

Section 602 of the Clean Air Act identifies ozone-depleting substances and divides them into two classes. Class I substances are divided into five groups, as shown in Exhibit 10. Section 604 of the Clean Air Act calls for a complete phase-out of Class I substances by January 1, 2000 (January 1, 2002, for methyl chloroform). Class II chemicals, which are hydrochlorofluorocarbons (HCFCs), are generally seen as interim substitutes for Class I CFCs.

Class II substances consist of 33 HCFCs. The law calls for a complete phase-out of Class II substances by January 1, 2030. The schedule for the HCFC phase-out has not yet been finalized; however, EPA has proposed to begin phase-out of some HCFCs by 2002, with a complete phase-out of all HCFCs to take place by 2030. This same proposal would phase-out CFCs, carbon tetrachloride, hydrobromofluorocarbons, and methyl chloroform by January 1, 1996. Halons used as fire extinguishers were to be phased-out by January 1, 1994.

On January 19, 1993, EPA issued a rule under Section 611 of the Clean Air Act that requires both domestically produced and imported goods containing or manufactured with Class I chemicals to carry a warning label. The rule covers items whose manufacture involves the use of Class I chemicals, even if the final product does not contain such chemicals. The EPA cited circuit boards, whose manufacture requires cleaning with methyl chloroform, as an example of an item of this type.

Exports are exempt from this rule's labeling requirements, as are products that do not have direct contact with these chemicals. In addition, if direct contact occurs but is non-routine and intermittent (e.g., spot-cleaning of textiles), no labeling is required. Moreover, if a second manufacturer incorporates a product made with an ozone-depleting chemical into another item, the final product need not carry a label.

Class I Substances

Group I
Chlorofluorocarbon-11 (CFC-11)
Chlorofluorocarbon-12 (CFC-12)
Chlorofluorocarbon-113 (CFC-113)
Chlorofluorocarbon-114 (CFC-114)
Chlorofluorocarbon-115 (CFC-115)
Group II
Group III
Chlorofluorocarbon-13 (CFC-13)
Chlorofluorocarbon-111 (CFC-111)
Chlorofluorocarbon-112 (CFC-112)
Chlorofluorocarbon-211 (CFC-211)
Chlorofluorocarbon-212 (CFC-212)
Chlorofluorocarbon-213 (CFC-213)
Chlorofluorocarbon-214 (CFC-214)
Chlorofluorocarbon-215 (CFC-215)
Chlorofluorocarbon-216 (CFC-216)
Chlorofluorocarbon-217 (CFC-217)
Group IV
Carbon tetrachloride
Group V
Methyl chloroform

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