Presidents and the Clean Air Act: From Eisenhower to Trump

Every U.S. president since Dwight D. Eisenhower has shaped the Clean Air Act, and the list of Clean Air Act presidents runs through the law’s original enactment under Lyndon Johnson, its 1970 overhaul under Richard Nixon, major amendments under Jimmy Carter and George H.W. Bush, and a modern back-and-forth in which Barack Obama, Donald Trump, and Joe Biden have used the same statute to reach opposite results. Some signed the law’s major versions. One created the agency that enforces it. Others have stretched or narrowed its reach through rulemaking, and the current administration has, for the first time in the statute’s history, used a presidential exemption power written into it.

Eisenhower and the 1955 Starting Point

Federal involvement in air pollution began with President Eisenhower. On July 14, 1955, he signed the Air Pollution Control Act, the first federal legislation on the subject. The law was narrow by design. It authorized up to $5 million a year for federal research and offered technical assistance to state and local governments, but regulatory authority stayed entirely with states and localities.¹ Air pollution was still treated as a local problem.

Lyndon Johnson Signed the First Clean Air Act

President Johnson signed the Clean Air Act itself on December 17, 1963, the first federal law aimed at controlling air pollution rather than just studying it.² It established a federal program within the U.S. Public Health Service, expanded research, and encouraged cooperation among federal, state, and local governments.³ Johnson said at the signing that more than 6,000 communities needed help and that over 100 million people in American cities were breathing polluted air.

Two more Johnson-era laws expanded that authority. The Motor Vehicle Air Pollution Control Act of October 1965 authorized federal emission standards for new cars and trucks for the first time and prohibited the sale of vehicles that did not meet them.⁴ The Air Quality Act of November 1967 authorized federal enforcement proceedings for interstate air pollution and funded the first large-scale studies of pollution sources. Johnson said the 1967 law authorized more spending on air pollution over three years than the country had devoted to the problem in the previous 180.⁵

Richard Nixon Rewrote the Law and Created the EPA

The version of the Clean Air Act that reshaped American environmental law was signed by President Nixon on December 31, 1970.⁶³ Nixon called it “the most important piece of legislation dealing with the problem of clean air that we have this year and the most important in our history.”

The vote was overwhelming. The Senate approved it 73 to 0 and the House passed it 374 to 1.⁷

Nixon also created the enforcement agency. Earlier in 1970 he sent Reorganization Plan No. 3 to Congress, proposing to consolidate pollution control functions from multiple departments into a single independent agency. Congress approved the plan, and the Environmental Protection Agency became operational on December 2, 1970, with William Ruckelshaus as its first administrator.⁸ The new agency became the enforcement arm for the Clean Air Act Nixon signed four weeks later.

Jimmy Carter and the 1977 Amendments

President Carter signed the Clean Air Act Amendments of 1977 on August 7, 1977.⁹ The amendments addressed two gaps in the 1970 law. For areas that already had clean air, the amendments created Prevention of Significant Deterioration provisions, which required major new sources to obtain permits and use the best available control technology so those areas would not slide down to the minimum federal standard. For areas still failing to meet air quality standards, called nonattainment areas, the amendments imposed requirements on new and modified sources and set deadlines to bring those areas into compliance.³ Carter also credited the amendments with protecting national parks, wilderness areas, and national monuments, and with setting a firm timetable for the auto industry to reduce emissions and improve fuel efficiency. The law authorized new economic penalties equal to the cost of cleanup for industries that delayed installing pollution controls.

George H.W. Bush and the 1990 Amendments

The most recent major rewrite came under President George H.W. Bush, who signed the 1990 amendments on November 15, 1990, ending what he called a “13-year legislative logjam.”¹⁰ The final legislation passed the Senate 89 to 10 and the House 401 to 25.⁷

The 1990 amendments tackled four problems:

Acid rain. The law created a cap-and-trade system for sulfur dioxide from power plants, which Bush called “the first large-scale regulatory use of market incentives.” The program aimed to cut sulfur dioxide by 10 million tons below 1980 levels and nitrogen oxide emissions by 2 million tons, and it ultimately achieved deeper cuts at lower cost than projected.¹⁰¹¹
Toxic air pollutants. The amendments expanded regulation to cover 189 hazardous substances and directed the EPA to set standards based on effective control technologies.¹¹³
Urban smog. The law strengthened requirements for areas failing to meet ozone standards and targeted an approximate 30-million-ton annual reduction in dangerous chemicals.¹⁰
Stratospheric ozone. The law added provisions to protect the ozone layer from chemicals like chlorofluorocarbons.¹²

The 1990 amendments remain the current legal authority for federal air pollution regulation. Congress has not enacted a major overhaul since.

Bill Clinton Tightened the Air Quality Standards

President Clinton did not sign new Clean Air Act legislation, but his administration used existing authority to revise the National Ambient Air Quality Standards. In July 1997, the EPA issued new standards for ozone and fine particulate matter.¹³ The ozone standard shifted from a one-hour to an eight-hour measurement, and the EPA established new standards for fine particles (PM2.5) with a monitoring network of about 1,500 stations.¹⁴

Industry groups sued. In Whitman v. American Trucking Associations (2001), the Supreme Court unanimously held that the Clean Air Act does not permit the EPA to consider implementation costs when setting national air quality standards, validating the Clinton approach.¹⁵ Clinton’s EPA administrator, Carol Browner, said the nation was committed to protecting public health “without regard to cost.”¹³

George W. Bush Pushed Cap-and-Trade Through Rulemaking

President George W. Bush pursued air pollution policy mainly through executive rulemaking. In February 2002, he proposed the Clear Skies Initiative, a cap-and-trade proposal modeled on the 1990 acid rain program to cut power plant emissions of sulfur dioxide, nitrogen oxides, and mercury by 70 percent over 15 years.¹⁶ It never passed Congress, but the administration implemented elements through regulation. The EPA finalized the Clean Air Interstate Rule, a cap-and-trade program to reduce sulfur dioxide and nitrogen oxides from power plants in 28 eastern states, and in March 2005 issued the Clean Air Mercury Rule, the first federal rule to cap mercury emissions from coal-fired plants. The administration also reworked the New Source Review permitting program to give industrial facilities more flexibility to modernize without triggering full permit reviews and finalized the Clean Air Nonroad Diesel Rule in 2004, targeting a 90 percent reduction in soot and nitrogen oxide from heavy-duty diesel engines.¹⁷

Barack Obama Used the Clean Air Act on Climate Change

The Obama administration used the Clean Air Act to address climate change in ways no earlier administration had attempted. The legal foundation was the Supreme Court’s 2007 decision in Massachusetts v. EPA, which held that greenhouse gases qualify as “air pollutants” under the Clean Air Act and that the EPA has statutory authority to regulate them from motor vehicles.¹⁵

The centerpiece was the Clean Power Plan, proposed in 2014. It used the EPA’s authority under Section 111 of the Clean Air Act to reduce carbon emissions from the power sector by 32 percent from 2005 levels by 2030. The administration also set vehicle emission standards projected to nearly double fuel economy for passenger vehicles by 2025, developed methane regulations for the oil and gas sector, and pursued an amendment to the Montreal Protocol to phase down hydrofluorocarbons.¹⁸

The Clean Power Plan never took effect. State attorneys general and power companies challenged it, and in February 2016 the Supreme Court issued a rare stay blocking implementation while litigation continued.¹⁹ The plan was struck down in West Virginia v. EPA in 2022.

Donald Trump: Rollbacks in Two Terms

First Term (2017–2021)

The Trump administration pursued deregulation under Executive Order 13771, which required agencies to eliminate two regulations for every new one. In June 2019 the EPA replaced the Clean Power Plan with the Affordable Clean Energy Rule, which defined the “best system of emission reduction” for power plants as on-site efficiency improvements rather than the sector-wide shift Obama had envisioned. The EPA’s own analysis projected the replacement rule would increase carbon dioxide emissions by over 60 million short tons by 2030 compared to the Clean Power Plan. The administration also rescinded methane emission standards for the oil and gas sector, withdrew the finding that regulating toxic pollutants from coal and oil plants was “appropriate and necessary” (even though the industry had already invested over $18 billion in compliance), and proposed rolling back federal clean car standards.²⁰

Second Term (2025–Present)

The second term has brought more aggressive action. In March 2025 the EPA invited factories to request two-year exemptions from Clean Air Act requirements by email. More than 180 facilities across 38 states and Puerto Rico received reprieves, and the EPA described the program as “the biggest deregulatory action in U.S. history.”²¹ The exemptions covered roughly one-third of all coal-fired power plants, one-quarter of all chemical manufacturers, and nearly half the commercial sterilization industry, among others. The administration cited Section 112(i)(4), which allows the president to exempt facilities from hazardous air pollution standards when the necessary technology is unavailable and the exemption serves national security. It was the first time in the 55-year history of that provision that any president had used it.²² About 250,000 people live within one mile of the exempted facilities, and more than 70 of the facilities had faced formal EPA enforcement actions in the preceding five years.

In February 2026 the EPA finalized the repeal of the 2009 Endangerment Finding, the scientific determination, upheld by the Supreme Court in Massachusetts v. EPA, that greenhouse gases endanger public health and welfare. The repeal also eliminated all greenhouse gas emission standards for vehicles.²³ On June 12, 2025, the president signed three Congressional Review Act resolutions blocking California’s authority to set stricter vehicle emission standards, waivers the EPA had granted the state more than 100 times over the decades.²⁴ In June 2025, EPA Administrator Lee Zeldin proposed repealing all greenhouse gas emission standards for the power sector under Section 111.²⁵

Joe Biden and Power Plant Carbon Rules

The Biden administration used Clean Air Act authority to impose the most comprehensive carbon pollution standards to date. On April 25, 2024, the EPA finalized rules requiring existing coal-fired and new baseload natural gas-fired power plants to control 90 percent of their carbon pollution, with projected reductions of 1.38 billion metric tons of carbon pollution through 2047 and up to $370 billion in climate and public health benefits.²⁶ The rules identified carbon capture and sequestration as the best system of emission reduction for long-term coal plants and formally repealed the Trump-era Affordable Clean Energy Rule.²⁷ The Biden EPA also strengthened the Mercury and Air Toxics Standards, tightening limits on toxic metals from coal plants by 67 percent and mercury from lignite-fired sources by 70 percent. The Trump administration began dismantling these rules upon taking office in 2025.

How the Supreme Court Has Limited What Presidents Can Do

Three Supreme Court decisions have repeatedly shaped what any president can accomplish under the Clean Air Act.

Whitman v. American Trucking Associations (2001) held unanimously that the EPA cannot consider implementation costs when setting national air quality standards.¹⁵

Massachusetts v. EPA (2007) held that greenhouse gases are “air pollutants” under the statute and that the EPA has authority to regulate them from motor vehicles, opening the door to climate regulation.¹⁵

West Virginia v. EPA (2022) struck down the Obama-era Clean Power Plan in a 6-3 decision. Chief Justice John Roberts applied the “major questions doctrine,” holding that agencies must point to “clear congressional authorization” before making “decisions of vast economic and political significance.” Justice Elena Kagan, in dissent, accused the majority of appointing itself “the decision-maker on climate policy.”²⁸ The ruling constrained future presidents from using the Clean Air Act to force broad, industry-wide energy transitions without explicit congressional authorization.

Ongoing litigation is testing the current administration’s actions. A coalition of 17 environmental and public health groups, including the American Lung Association and the Sierra Club, sued in the D.C. Circuit in February 2026 to challenge the repeal of the Endangerment Finding, arguing the agency is “rehashing legal arguments that the Supreme Court already considered and rejected” in Massachusetts v. EPA.²⁹ California and 10 other states are challenging the June 2025 Congressional Review Act resolutions that blocked California’s vehicle emissions waivers, arguing the waivers were adjudicatory orders rather than rules and could not be subject to CRA disapproval.³⁰

1
GovInfo. Air Pollution Control Act of 1955
2
The American Presidency Project. Remarks Upon Signing the Clean Air Act
3
EPA. Evolution of the Clean Air Act
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GovInfo. Public Law 89-272
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The American Presidency Project. Remarks Upon Signing the Air Quality Act of 1967
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The American Presidency Project. Remarks on Signing the Clean Air Amendments of 1970
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NRCM. Climate Action Needs Bipartisan Spirit of the Clean Air Act
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EPA. Origins of the EPA
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The American Presidency Project. Clean Air Act Amendments of 1977 Statement on Signing H.R. 6161 Into Law
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The American Presidency Project. Statement on Signing the Bill Amending the Clean Air Act
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Harvard Law School EELP. What Environmental Protection Owes George H.W. Bush
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EPA. Clean Air Act Highlights of the 1990 Amendments
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Resources for the Future. Clinton Administration Environmental Policy
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The American Presidency Project. Memorandum on Implementation of Revised Air Quality Standards for Ozone and Particulate Matter
15
Justia. Supreme Court Cases by Topic: Climate Change and Environment
16
The White House (George W. Bush). Clear Skies Initiative
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The White House (George W. Bush). Clean Air
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The Obama White House Archives. The Record: Climate
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ASIL. Clean Air Act and Climate Change
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Brookings. The Trump Administration’s Major Environmental Deregulations
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ProPublica. Clean Air Act Exemptions
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NRDC. Free Pass for Polluters: Presidential Exemptions From the Clean Air Act
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EPA. Final Rule: Rescission of Greenhouse Gas Endangerment
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The White House. Statement by the President
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EPA. Greenhouse Gas Standards and Guidelines for Fossil Fuel-Fired Power
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EPA. Biden-Harris Administration Finalizes Suite of Standards to Reduce Pollution From Fossil Fuel-Fired Power Plants
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Federal Register. New Source Performance Standards for Greenhouse Gas Emissions
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SCOTUSblog. Supreme Court Curtails EPA’s Authority to Fight Climate Change
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Clean Air Task Force. U.S. EPA Sued Over Illegal Repeal of Climate Protections
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Climate Case Chart. California v. United States