A Guide to the Clean Air Act Requirements, Process, and Compliance

The Clean Air Act (CAA) stands as a pillar of environmental protection in the United States, safeguarding the air we breathe and the health of our communities. This comprehensive guide delves into the intricacies of the CAA, providing a clear and accessible resource for those navigating its complex regulatory landscape. From understanding the Act's history and key amendments to exploring its regulated activities, emissions standards, and compliance strategies, this guide offers a thorough examination of the CAA's scope and impact. Readers will gain a deep understanding of the Act's role in controlling air pollution from stationary and mobile sources, as well as the monitoring, reporting, and enforcement mechanisms that ensure its effectiveness. The guide also highlights the importance of staying informed about regulatory changes and provides valuable resources for further learning and engagement. By the end of this guide, readers will be well-equipped to manage the challenges and opportunities presented by the Clean Air Act, armed with the knowledge and tools needed to contribute to a cleaner, healthier environment for all.


Key Details of the Clean Air Act

  • Issuing Agency: Environmental Protection Agency
  • Year Established: 1963
  • Last Amended: 1990
  • Statutory Authority: Clean Air Act
  • Primary Legal Reference: Title 40, Chapter I, Subchapter C, Parts 50-97 of the Code of Federal Regulations

What is the Clean Air Act?

The Clean Air Act (CAA) is a comprehensive federal law that regulates air emissions from stationary and mobile sources. The CAA operates within the broader framework of environmental regulations administered by the Environmental Protection Agency (EPA). The primary goal of the CAA is to protect public health and welfare by reducing air pollution and improving air quality across the United States.

The CAA was first enacted in 1963 and has been amended several times, most significantly in 1970, 1977, and 1990. The 1970 amendments established the National Ambient Air Quality Standards (NAAQS), which set allowable levels of six criteria pollutants: particulate matter, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. The 1977 amendments introduced the Prevention of Significant Deterioration (PSD) program and the New Source Review (NSR) permitting process for major sources of air pollution. The 1990 amendments expanded the regulation of toxic air pollutants, established the Acid Rain Program, and introduced market-based mechanisms like emissions trading.

The CAA's general approach involves setting national air quality standards, requiring states to develop plans to meet those standards, and regulating emissions from both stationary sources (like factories and power plants) and mobile sources (like cars and trucks). The EPA is responsible for setting the NAAQS and overseeing state implementation plans, while states are primarily responsible for enforcing the CAA within their borders.

The CAA applies throughout the United States, including all 50 states, U.S. territories, and Indian country. It regulates a wide range of entities, from large industrial facilities to small businesses and individual motor vehicles. However, the CAA does include some exemptions for certain activities, such as agricultural operations and some small businesses.

What does the Clean Air Act protect?

The Clean Air Act protects the air we breathe by setting limits on the amount of pollution that can be emitted into the air. The CAA's primary focus is on reducing outdoor air pollution from a variety of sources, including:

  1. Criteria pollutants: The six common air pollutants that are regulated under the NAAQS - particulate matter, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. 1

  2. Hazardous air pollutants: Also known as air toxics, these are pollutants that are known or suspected to cause cancer or other serious health effects, such as reproductive effects or birth defects, or adverse environmental effects.2

  3. Acid rain: The CAA's Acid Rain Program reduces emissions of sulfur dioxide and nitrogen oxides, which are the primary causes of acid rain.3

  4. Stratospheric ozone depletion: The CAA includes provisions to protect the stratospheric ozone layer by phasing out the production and use of ozone-depleting substances.4

By setting emissions standards, requiring pollution control technologies, and establishing permitting programs for major sources of air pollution, the CAA works to reduce the levels of these pollutants in the air and protect public health and the environment.


Regulated Activities, Entities & Prohibited Substances

The Clean Air Act (CAA) regulates a wide range of activities and entities that emit air pollutants, including industrial facilities, power plants, manufacturing processes, and mobile sources such as vehicles and aircraft. The Act aims to control and reduce emissions of criteria pollutants, hazardous air pollutants (HAPs), and greenhouse gases (GHGs) to protect public health and the environment.

Prohibited activities and substances under the Clean Air Act include:

  1. Emitting criteria pollutants (such as particulate matter, ozone, carbon monoxide, nitrogen oxides, sulfur dioxide, and lead) in excess of National Ambient Air Quality Standards (NAAQS).
  2. Constructing or modifying major sources of air pollutants without obtaining the necessary permits, such as New Source Review (NSR) permits.
  3. Operating major sources of air pollutants without obtaining a Title V Operating Permit.
  4. Emitting hazardous air pollutants (HAPs) listed under Section 112 of the CAA without proper control technologies or permits.
  5. Producing or consuming ozone-depleting substances (ODS) in violation of the Montreal Protocol and CAA Title VI regulations.
  6. Selling, distributing, or using gasoline that does not meet the required fuel standards and additives requirements under CAA Title II.

These prohibitions are based on the scientific understanding of the harmful effects of air pollutants on human health and the environment, as well as the need to control emissions from various sources to maintain air quality and protect public welfare.

Key Sections of the Clean Air Act

Sections 108 and 109 - National Ambient Air Quality Standards (NAAQS)

  • Purpose: Establish health-based standards for criteria pollutants to protect public health and welfare.
  • Requirements: EPA must set and periodically review NAAQS for six criteria pollutants.
  • Significance: Provides the foundation for air quality management and emissions control programs.
  • Compliance strategies: Monitor ambient air quality, implement emissions control measures, and develop State Implementation Plans (SIPs) to attain and maintain NAAQS.

Parts C and D of Title I - New Source Review (NSR) Permitting

  • Purpose: Ensure that new or modified major sources of air pollutants do not significantly deteriorate air quality or contribute to NAAQS violations.
  • Requirements: Major sources must obtain NSR permits, install Best Available Control Technology (BACT) or Lowest Achievable Emission Rate (LAER), and offset emissions increases.
  • Significance: Helps maintain air quality in attainment areas and improve air quality in non-attainment areas.
  • Compliance strategies: Determine applicability, apply for NSR permits, install required control technologies, and secure emission offsets.

Sections 501-507 - Title V Operating Permits

  • Purpose: Consolidate all CAA requirements for major sources into a single, comprehensive operating permit.
  • Requirements: Major sources must obtain Title V permits, comply with all applicable CAA requirements, and submit regular compliance reports.
  • Significance: Enhances compliance, transparency, and public participation in air quality management.
  • Compliance strategies: Determine applicability, apply for Title V permits, develop compliance plans, and maintain records and reports.

Section 110(a)(2)(C) - Fugitive Dust Control

  • Purpose: Minimize fugitive dust emissions from construction, demolition, and other dust-generating activities.
  • Requirements: States must include fugitive dust control measures in their SIPs, and sources must implement these measures.
  • Significance: Reduces public exposure to particulate matter and helps maintain ambient air quality.
  • Compliance strategies: Develop and implement fugitive dust control plans, employ best management practices (BMPs), and monitor and report emissions.

Title II - Mobile Source Emissions

  • Purpose: Control emissions from mobile sources, including vehicles, engines, and fuels.
  • Requirements: Manufacturers must comply with emission standards, fuel suppliers must meet fuel quality requirements, and vehicle owners must maintain emission control systems.
  • Significance: Mobile sources are a significant contributor to air pollution, and Title II regulations help reduce their emissions.
  • Compliance strategies: Develop and implement mobile source control programs, enforce emission standards and fuel requirements, and promote clean transportation technologies.

Relationship to Other Regulations & Agencies

The Clean Air Act interacts with various other federal, state, and local regulations and agencies in the following ways:

  1. State Implementation Plans (SIPs): Under CAA Section 110, states are required to develop SIPs that outline how they will attain and maintain NAAQS. These plans must be approved by the EPA and may include state-specific regulations and programs that complement or exceed federal requirements.

  2. National Environmental Policy Act (NEPA): Major federal actions, including projects requiring federal permits or funding, must undergo environmental review under NEPA. This process often involves assessing a project's potential air quality impacts and compliance with CAA requirements.

  3. Endangered Species Act (ESA): The EPA must consult with the U.S. Fish and Wildlife Service and the National Marine Fisheries Service to ensure that CAA actions, such as issuing permits or approving SIPs, do not jeopardize the continued existence of threatened or endangered species.

  4. Occupational Safety and Health Administration (OSHA): OSHA regulates workplace exposure to air pollutants and sets Permissible Exposure Limits (PELs) for various substances. These requirements may overlap with CAA regulations for industrial sources.

  5. Local air quality agencies: Many states and local governments have their own air quality agencies that implement and enforce CAA requirements, as well as additional local regulations. These agencies often work closely with the EPA and regulated entities to ensure compliance and maintain air quality.

In terms of roles and responsibilities, the EPA is the primary federal agency responsible for implementing and enforcing the Clean Air Act. The EPA sets NAAQS, develops regulations and guidance, issues permits, and oversees state and local air quality programs. Other federal agencies, such as the Department of Transportation and the Department of Energy, also play a role in regulating mobile sources and promoting clean energy technologies.

State and local air quality agencies are responsible for developing and implementing SIPs, issuing permits, conducting inspections, and enforcing CAA requirements within their jurisdictions. These agencies often have the authority to adopt more stringent standards and regulations than the federal requirements.

Regulated entities, such as industrial facilities, power plants, and vehicle manufacturers, are responsible for complying with CAA requirements, obtaining necessary permits, installing control technologies, and reporting emissions. They must work closely with federal, state, and local agencies to ensure compliance and maintain air quality.


Regulatory Standards & Limitations

The Clean Air Act and its implementing regulations establish various standards and limitations to control air pollution from stationary and mobile sources. These standards include:

  1. National Ambient Air Quality Standards (NAAQS): The EPA sets NAAQS for six criteria pollutants: particulate matter, ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, and lead.5 States must develop plans to attain and maintain these standards.6

  2. New Source Performance Standards (NSPS): The EPA establishes technology-based emissions standards for specific categories of new, modified, or reconstructed stationary sources.7 These standards are based on the best available control technology (BACT) for each source category.8

  3. National Emission Standards for Hazardous Air Pollutants (NESHAPs): The EPA sets emissions standards for 187 hazardous air pollutants (HAPs) from specific source categories.9 These standards are based on the maximum achievable control technology (MACT) for each source category.10

  4. Mobile Source Emissions Standards: The EPA sets emissions standards for various classes of vehicles and engines, including cars, trucks, buses, and non-road vehicles and equipment.11 These standards limit emissions of pollutants such as hydrocarbons, nitrogen oxides, and particulate matter.12

The EPA and state environmental agencies implement and enforce these standards through permitting, monitoring, and inspection programs. Regulated entities must comply with applicable standards and may face penalties for violations.

Monitoring, Reporting & Recordkeeping Obligations

Under the Clean Air Act, regulated entities must comply with various monitoring, reporting, and recordkeeping requirements to demonstrate compliance with applicable emissions standards and permit conditions.13 These obligations may include:

  1. Emissions Monitoring: Regulated entities must install, calibrate, maintain, and operate continuous emissions monitoring systems (CEMS) or other approved monitoring methods to measure and record emissions data.14

  2. Periodic Reporting: Regulated entities must submit periodic reports to the EPA or state agencies, detailing emissions data, compliance status, and any exceedances or malfunctions.15 The frequency and content of these reports vary depending on the applicable requirements and permit conditions.16

  3. Recordkeeping: Regulated entities must maintain records of emissions data, monitoring results, compliance certifications, and other relevant information for a specified period, typically ranging from three to five years.17 These records must be available for inspection by regulatory authorities.18

Monitoring, reporting, and recordkeeping requirements are essential for ensuring compliance with the Clean Air Act and providing transparency to regulators and the public. Accurate and timely data helps agencies identify violations, assess the effectiveness of control measures, and make informed decisions about air quality management.

Enforcement Actions & Penalties

The EPA and state environmental agencies conduct inspections and audits to monitor compliance with the Clean Air Act. The types of inspections include:

Inspection TypeDescriptionFrequency
RoutineRegularly scheduled inspections based on the facility's compliance history and potential for violationsVaries, typically every 1-5 years
TargetedFocused inspections based on specific concerns, such as citizen complaints or industry-wide compliance issuesAs needed
Complaint-drivenInspections in response to specific complaints from the public or other sourcesAs needed

During inspections, regulated entities must provide access to facilities, records, and personnel, and cooperate with inspectors.19 Entities have the right to be represented by counsel and to receive a copy of the inspection report.

Violations of the Clean Air Act can result in various penalties, depending on the nature and severity of the violation:

Penalty TypeDescriptionExamples of ViolationsFactors Affecting Severity
AdministrativeFines or orders issued by the EPA or state agencies without court actionMinor violations, such as recordkeeping errors or reporting delaysCompliance history, duration of violation, harm to public health or environment
CivilFines or injunctive relief imposed through court actionSignificant violations, such as exceeding emissions limits or operating without a required permitSame as administrative factors, plus economic benefit of noncompliance and seriousness of violation
CriminalFines and/or imprisonment for intentional or knowing violationsKnowingly falsifying monitoring data, tampering with control equipment, or engaging in other criminal actsIntent, compliance history, harm to public health or environment, and involvement of senior management

Civil penalties can reach up to $37,500 per day per violation, while criminal fines can reach $250,000 for individuals and $500,000 for organizations, with possible imprisonment of up to 5 years.20

Compliance Assistance & Regulatory Incentives

The EPA and state environmental agencies offer various programs, resources, and incentives to help entities understand and comply with the Clean Air Act:

  1. Technical Assistance: The EPA provides guidance documents, fact sheets, and online tools to help regulated entities interpret and meet regulatory requirements. State agencies may also offer technical assistance tailored to local needs and industries.

  2. Training and Workshops: The EPA and state agencies offer training sessions, workshops, and webinars on topics such as permit requirements, emissions monitoring, and pollution control technologies. Industry groups and trade associations may also provide compliance-related training.

  3. Financial Incentives: The EPA and other federal agencies offer grants, loans, and tax credits to encourage the adoption of cleaner technologies and practices.21 Examples include the Diesel Emissions Reduction Act (DERA) grant program and the Clean Air Technology Center (CATC) financial assistance program.

  4. Voluntary Partnership Programs: The EPA administers several voluntary programs that provide recognition, technical assistance, and other incentives for entities that commit to superior environmental performance. Examples include:

    • The National Environmental Performance Track, which offers regulatory flexibility and streamlined permitting for facilities with strong environmental records22.
    • The Clean Air Excellence Awards, which recognize innovative and effective air quality initiatives by businesses, government agencies, and other organizations23.

Entities interested in these assistance and incentive programs should visit the EPA's compliance assistance website (https://www.epa.gov/compliance) or contact their state environmental agency for more information on eligibility, application processes, and potential benefits.


Regulatory History & Upcoming Changes

The Clean Air Act (CAA) was originally enacted in 1963 and has undergone several significant amendments since then. The major amendments and their key provisions include:

  1. Clean Air Act Amendments of 1970: Established the National Ambient Air Quality Standards (NAAQS) and required states to develop plans to meet these standards. It also expanded federal enforcement authority and established the New Source Performance Standards (NSPS) for new and modified stationary sources of pollution.24

  2. Clean Air Act Amendments of 1977: Added provisions for the Prevention of Significant Deterioration (PSD) of air quality in areas meeting the NAAQS and requirements for Best Available Control Technology (BACT) for new major sources in these areas. It also established the Nonattainment New Source Review (NNSR) program for areas not meeting the NAAQS.25

  3. Clean Air Act Amendments of 1990: Introduced the Acid Rain Program to reduce sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions from power plants, established the Title V operating permit program, and expanded the regulation of toxic air pollutants under the National Emission Standards for Hazardous Air Pollutants (NESHAP) program.26

These amendments were driven by growing public concern over air pollution and its impacts on human health and the environment. Each set of amendments strengthened the CAA's regulatory framework and expanded the EPA's authority to enforce air quality standards and regulate emissions from various sources.

In recent years, there have been several notable regulatory changes and proposed rules related to the CAA, including:

  • The Clean Power Plan (2015): Aimed to reduce carbon dioxide emissions from existing power plants, but was repealed in 2019 and replaced with the Affordable Clean Energy (ACE) rule.27
  • The Affordable Clean Energy (ACE) rule (2019): Established emission guidelines for states to develop plans to reduce greenhouse gas emissions from existing coal-fired power plants. However, the rule was vacated by the U.S. Court of Appeals for the D.C. Circuit in 2021.28
  • Proposed revisions to the Ozone NAAQS (2020): The EPA proposed to retain the current ozone NAAQS set in 2015, despite calls from environmental groups to strengthen the standards.29

To stay informed about upcoming regulatory changes and proposed rules, stakeholders should regularly monitor the EPA's website, the Federal Register, and industry publications. Engaging in the public comment process during rulemaking can also help shape the development of new regulations and ensure that the interests of regulated entities and the public are considered.

Additional Resources

  1. Full text of the Clean Air Act and its amendments: https://www.epa.gov/clean-air-act-overview/clean-air-act-text

    • This link provides access to the complete text of the Clean Air Act and its subsequent amendments, which is essential for understanding the legal requirements and provisions of the regulation.
  2. EPA's Clean Air Act Overview: https://www.epa.gov/clean-air-act-overview

    • The EPA's Clean Air Act overview page provides a comprehensive introduction to the CAA, including its history, key programs, and regulatory framework. It also offers links to additional resources and guidance documents.
  3. EPA's Air Quality Planning and Standards: https://www.epa.gov/air-quality-implementation-plans

    • This page provides information on the development and implementation of air quality standards under the CAA, including the NAAQS, SIPs, and related programs.
  4. "Fundamentals of Air Pollution" by Daniel A. Vallero (2014): https://www.elsevier.com/books/fundamentals-of-air-pollution/vallero/978-0-12-401733-7

    • This academic textbook provides a comprehensive introduction to air pollution, its sources, and its impacts on human health and the environment. It offers a solid foundation for understanding the scientific and technical aspects of air quality management and regulation.


  1. 40 C.F.R. Part 50

  2. 40 C.F.R. Part 63

  3. 40 C.F.R. Parts 72-78

  4. 40 C.F.R. Part 82

  5. 42 U.S.C. § 7409

  6. 42 U.S.C. § 7410

  7. 42 U.S.C. § 7411

  8. 40 C.F.R. Part 60

  9. 42 U.S.C. § 7412(b)

  10. 40 C.F.R. Part 63

  11. 42 U.S.C. § 7521

  12. 40 C.F.R. Parts 85-86, 1036-1037

  13. 42 U.S.C. § 7414

  14. 40 C.F.R. Part 75

  15. 40 C.F.R. § 70.6(a)(3)

  16. 40 C.F.R. Parts 60, 63, 70-71

  17. 40 C.F.R. § 70.6(a)(3)(ii)

  18. 42 U.S.C. § 7414(a)

  19. 42 U.S.C. § 7414(a)

  20. 42 U.S.C. § 7413(b)-(c)

  21. EPA. (n.d.). Air Grants and Funding. https://www.epa.gov/grants/air-grants-and-funding

  22. EPA. (n.d.). National Environmental Performance Track. https://archive.epa.gov/performancetrack/web/html/index.html

  23. EPA. (n.d.). Clean Air Excellence Awards. https://www.epa.gov/caaac/clean-air-excellence-awards

  24. Clean Air Act Amendments of 1970, Pub. L. No. 91-604, 84 Stat. 1676 (1970).

  25. Clean Air Act Amendments of 1977, Pub. L. No. 95-95, 91 Stat. 685 (1977).

  26. Clean Air Act Amendments of 1990, Pub. L. No. 101-549, 104 Stat. 2399 (1990).

  27. 80 Fed. Reg. 64,662 (Oct. 23, 2015).

  28. 84 Fed. Reg. 32,520 (July 8, 2019); Am. Lung Ass'n v. EPA, 985 F.3d 914 (D.C. Cir. 2021).

  29. 85 Fed. Reg. 87,256 (Dec. 31, 2020).

Keep up with the latest

A Note to Our Readers: We hope this guide is a valuable resource in helping you better understand the Clean Air Act. However, it's not a substitute for professional advice and doesn't cover every scenario. Always consult with regulatory bodies and professionals for the most current advice and project-specific guidance.