Clean Air Act: An Overview

Background and Statutory Framework

The Clean Air Act (“CAA”) seeks “to protect and enhance the quality of the Nation’s air resources so as to promote the public health and welfare and the productive capacity of its population.” 42 U.S.C. § 7401. In 1955, the CAA was enacted and later amended in 1970, 1977, and 1990 in an effort to protect the nation’s air quality. 42 U.S.C. 7401–7675. Prior to 1955, air pollution was the exclusive responsibility of state and local levels of government.

The 1970 amendments established the  Environmental Protection Agency’s (“EPA”) authority to set national standards for ambient air quality These amendments also required a 90% reduction in emissions from new automobiles by 1975.They established programs to require the best available control technology at major new sources of air pollution, and to regulate air toxics. Lastly, they greatly strengthened federal enforcement authority.

The 1977 amendments adjusted the auto emission standards, extended deadlines for the attainment of air quality standards, and added the Prevention of Significant Deterioration program to protect air cleaner than national standards.

The 1990 amendments included provisions to (1) classify most nonattainment areas according to the extent to which they exceed the standard, tailoring deadlines, planning, and controls to each area’s statutes; (2) tighten auto and other mobile source emission standards; (3) require reformulated and alternative fuels in the most polluted areas; (4) revise the air toxics section, establishing a new program of technology-based standards and addressing the problem of sudden, catastrophic releases of air toxics; (5) establish an acid rain control program, with a marketable allowance scheme to provide flexibility in implementation; (6) require a state-run permit program for the operation of major sources of air pollutants; (7) implement the Montreal Protocol to phase out most ozone-depleting chemicals; and (8) update the enforcement provisions so that they parallel those in other pollution control acts, including authority for EPA to assess administrative penalties. In addition, the 1990 amendments authorized appropriations for clean air programs through FY1998.

Notably, the CAA provides a comprehensive and complex regulatory framework for regulating stationary and mobile sources of air pollution, their fuels, for sources of 187 hazardous air pollutants, and it establishes a cap-and-trade program for the emissions that cause acid rain. It establishes a comprehensive permit system for all major sources of air pollution. It requires the EPA to establish minimum national standards for air quality and assigns primary responsibility for enforcement and compliance to the states. The CAA also establishes a permit system for all major sources of pollution and addresses prevention of pollution in areas with clean air.

National Ambient Air Quality Standards

The CAA requires the EPA to establish National Ambient Air Quality Standards (“NAAQS”) for pollutants that the EPA determines endanger public health or welfare. 42 U.S.C. § 7409. The NAAQS are designed to protect public health with an adequate margin of safety and to protect the public welfare from any known or anticipated adverse effects. Under this authority, the EPA has established NAAQS for six different air pollutants: sulfur dioxide (SO2), particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), carbon monoxide (CO), ozone, and lead.  State compliance is required for the EPA’s regulations for these air pollutants.  Importantly, the EPA must review the scientific data upon which the standards are based every five years, and revise the standards, if necessary.

State Implementation Plans (SIPs)

To carry out the regulations set by the EPA, states must develop State Implementation Plans (“SIPs”) and must submit those plans to the EPA for approval. 42 U.S.C. § 7410.  If approved, the SIPs carry the force of federal law, and the states must comply with the approved standards.  States develop SIPs based on emission inventories and computer models to determine whether air quality violations will occur.  If the data show that the standards are exceeded, then the states must impose additional controls to conform to the regulations. The EPA must approve any deviation or change in an existing SIP. Ultimately, a Federal Implementation Plan may be imposed if the state fails to submit or implement an adequate SIP.

Nonattainment Areas

Areas not meeting the required standards, known as “nonattainment areas”, are subject to stricter EPA enforcement procedures.  The CAA classifies nonattainment areas based on the extent to which the area exceeds NAAQS.  The CAA sets forth specific pollution controls and attainment dates for each classification. 42 U.S.C. §§ 7501–7515.

Other Major Provisions

Other major provisions of the CAA include

    • Transported Air Pollution, 42 U.S.C. § 7410(a)(2)(D)
      • Ensures that the SIPs include adequate provisions to prevent sources from within the state from polluting downwind states.
  • Emission Standards for Mobile Sources, 42 U.S.C. § 7408
  • Hazardous Air Pollutants, 42 U.S.C. § 7412
  • New Source Performance Standards, 42 U.S.C. § 7411
      • Requires the EPA to establish national standards for categories of new industrial facilities.
  • Prevention of Significant Deterioration of Air Quality, 42 U.S.C. §§ 7470–79
  • Permits, 42 U.S.C. §§ 7502–03
      • Requires states to administer a permit program for the operation of sources emitting air pollutants.

Links to these provisions are located in the Reading Room.

Agriculture

Notably, most agricultural operation’s emissions tend to fall below the CAA’s threshold to be classified as a “major source,” which renders them exempt from most CAA regulatory programs, but not in totality. As, the CAA will apply to any agricultural operation that meets its definition of “major”.

Today, agricultural air pollution has become more of an issue as EPA implements NAAQS for particulates and as nonattainment areas look for ways to reduce pollutants. Particularly, emissions from animal feeding operations, such as ammonia, can transform into secondary particulate matter that could violate the NAAQS.  Other agriculture pollutants include dust stirred from operations, diesel emissions from farm equipment, and emissions from crop burning.  With pressure from advocacy groups, further regulations for these emissions may be forthcoming.  As a result, CAA compliance and any relevant laws is important for any agricultural stakeholder to avoid EPA enforcements.

Federal Regulatory Authority

Under the CAA, administrative agencies such as USDA/FDA/EPA have Congressional authority to create regulations implementing federal law requirements. In 2024, the Supreme Court of the United States issued two rulings that are expected to have a major impact on how judges decide cases challenging those regulations and that agency authority.

Loper Bright Enters. v. Raimondo, 144 S. Ct. 2244 (2024) overruled the long-standing doctrine of deference established in Chevron, U.S.A., Inc. v. Nat. Res. Def. Council, Inc., 467 U.S. 837 (1984). Chevron deference was a two-step process that clarified how and when federal courts should defer to an agency regulation interpreting a statute.  Chevron only applied in situations where a court had determined that the statutory language the agency was interpreting was ambiguous.  If it was ambiguous, the court would consider whether the agency’s interpretation of the statutory language was “reasonable”.  If it was reasonable, the court was required to defer to the agency’s interpretation. If it was not, the court would overrule the interpretation.

Loper Bright formally overturned Chevron. In a 6-3 decision, the Supreme Court held that “courts may not defer to an agency interpretation of the law simply because a statute is ambiguous[.]” Following the ruling, courts are instead required to exercise independent judgment in determining whether an administrative agency has acted within its statutory authority.  Courts may still seek guidance from the agencies involved, but courts will no longer be required to defer to an agency’s interpretation of a statute.

In Corner Post, Inc. v. Bd. of Governors of the Fed. Rsrv. Sys., 144 S. Ct. 2440 (2024), the Supreme Court extended the period of time during which a party may file a lawsuit challenging federal agency actions. According to 28 U.S.C.S. § 2401(a), the six-year statute of limitations began to run when an administrative agency’s action was “final.”  In Corner Post, the Supreme Court ruled that an action becomes “final” when a plaintiff suffers an injury, rather than when a “final regulation” is released. This ruling expands the potential for plaintiffs to challenge federal agency rules and regulations that have been final for over six years.

While the full effect of these two rulings remains to be seen, it is highly likely that the agricultural industry will be impacted. As the rulings fundamentally change how courts will resolve lawsuits challenging agency regulations for misinterpreting the agency’s statutory authority. Impacts are most likely to be felt in areas of the law, such as CAA, dominated by statutes with relatively ambiguous language where Congress has relied on agency regulations to fill in specifics.