Navigating the Impacts of Rescinding the Endangerment Finding on Pollutant Regulations and Legal Challenges

Natalia Jaramillo
Feb 25
9 min read

Updated: Feb 25

Introduction

In the Supreme Court case of Massachusetts v. EPA, it was determined that greenhouse gases are considered air pollutants under the Clean Air Act. The "endangerment finding" serves as the legal foundation for all EPA regulations concerning greenhouse gases (GHGs). This finding determined that six GHGs pose a threat to public health, thereby requiring the EPA to implement regulations for these gases. The Trump Administration's move to revoke the endangerment finding is expected to have far-reaching effects on both the environment and human health. In this post, I will examine the potential outcomes and legal ramifications of this decision.

What Is the Endangerment Finding?

The endangerment finding, introduced in 2009 during the Obama administration, was the result of years of advocacy by environmental organizations pushing for stricter controls on gases. This finding includes six greenhouse gases: methane, carbon dioxide, nitrous oxide, hydrochlorocarbons, perfluorocarbons, and sulfur hexafluoride. The 1970 Clean Air Act facilitated this by giving the EPA the authority to regulate air pollutants. Since the EPA is responsible for

regulating harmful pollutants and these six GHGs were deemed harmful, the EPA was required to regulate them. Instead of capping all global warming gases, the EPA concentrated on key sectors, such as vehicle tailpipe emissions, power plant smokestacks, and emissions from oil and gas extraction. Revoking endangerment abolishes such regulations and reignites the conservative anti-regulatory movement that started in the Reagan era.

Immediate Effects of Rescinding the Endangerment Finding

In the short term, these changes would likely slow or halt progress on existing emissions standards. Industries that currently face limits on carbon dioxide and methane output could see relaxed rules or delayed implementation schedules. Such deregulation may lead to higher levels of air pollutants and greenhouse gas emissions, diminishing the federal government’s capacity to address climate change comprehensively.

The effects would extend well beyond emissions levels. As the EPA notes, reductions in air pollution and urban heat are directly linked to public health outcomes, meaning communities could face higher energy costs as temperatures rise. Warmer conditions increase demand for cooling, which burdens the power grid and drives up household energy bills. A Stanford study found that emergency room visits increase sharply on hotter days, suggesting that weaker emissions and climate protections would also raise health care costs, particularly for vulnerable populations.

Source: https://www.ankitparakh.com/wp-content/uploads/2021/12/HEALTH-EFFECTS-OF-AIR-POLLUTION-WEB.jpg

Economic impacts would follow close behind. As climate-related disasters grow more frequent and severe, insurance premiums are expected to rise, while coverage is becoming harder to obtain or afford in high-risk regions. Declining access to insurance undermines home affordability and can depress property values, leading to falling local tax revenues. When that happens, communities lose funding for essential services like schools, emergency response, and public infrastructure—illustrating how environmental deregulation can ripple through entire local economies.

By beginning with a repeal of vehicle emissions standards, the EPA would target the most direct application of the Endangerment Finding—the sector where it was first enforced. But this action sets off a domino effect across the broader regulatory framework. If the agency concludes that greenhouse gases from vehicles no longer pose a danger, it undermines the legal basis for regulating carbon emissions in other sectors as well, from manufacturing to electricity generation. This erosion of legal authority ties the fate of the entire U.S. climate policy framework to the outcome of a single decision—one that could shape environmental governance for decades to come.

Long-Term Environmental Consequences

Over time, rescinding the Endangerment Finding would have far-reaching consequences for air quality, public health, and the United States’ ability to meet its climate goals. Vehicle emissions alone play a major role: according to the EPA’s greenhouse gas inventory, annual U.S. vehicle carbon dioxide emissions exceed those of every country except China, India, and Russia. Rolling back regulations on these emissions would add billions of tons of additional carbon dioxide to the atmosphere over the coming decades. While the EPA has sometimes downplayed these numbers by arguing that U.S. emissions are a “small share” of the global total, that reasoning ignores how every percentage point of reduction matters. As the Global Carbon Project shows, sustained efforts from each major emitter are necessary to prevent catastrophic global warming.

Reducing “just a few percent” of global emissions can have an outsized impact: limiting pollution from U.S. motor vehicles would yield billions of dollars in annual economic benefits by improving air quality and reducing heat-related illnesses. Conversely, weakening these protections risks substantial harm. Analysts estimate that removing the endangerment foundation for regulation could lead to 58,000 additional deaths from climate-driven disasters and deteriorating air quality, along with 37 million more asthma attacks due to increased particulate matter and ozone exposure. These health outcomes compound across decades, magnifying social inequities and placing heavier burdens on low-income and frontline communities.

Climate change mitigation efforts would also suffer. The endangerment finding underlies emissions standards for passenger cars, trucks, and power plants, along with industrial and federal sustainability programs that guide investment and procurement decisions throughout the economy. Removing this foundation could destabilize markets and reverse progress toward a low-carbon transition. Power plants—both coal and natural gas—would face less pressure to adopt cleaner technologies, slowing the pace of decarbonization.

At the national level, the rollback jeopardizes America’s credibility in global climate negotiations. If the U.S. abandons its emissions oversight, other countries may follow suit—stalling coordinated global efforts that depend on mutual accountability. The threshold argument—that the U.S. share of emissions is too small to be meaningful—sets a dangerous precedent internationally, effectively inviting every nation to shirk its role in addressing a collective problem.

Meanwhile, the ripple effects would cascade down to the state level. Some states, such as California and those allied through regional climate agreements, are likely to maintain or even strengthen local emissions controls. Others may relax oversight, deepening disparities in air quality and environmental health across regions. The result would be a fragmented environmental landscape where outcomes depend heavily on geography and state policy priorities.

Communities would experience the long-term consequences most acutely. Intensifying floods, wildfires, and droughts will strain already vulnerable water and energy systems, and some regions may become too unsafe or costly to inhabit. These cascading effects—from infrastructure repairs and emergency responses to mass displacement—will exact enormous economic tolls, as outlined by the 2025 Global Climate Risk Index. Fuel prices are likely to rise about 25 cents per gallon by 2035 under current trajectories, imposing an estimated $1.7 trillion cost on consumers. Such costs highlight how short-term rollback savings for industry pale in comparison to the long-term financial and human costs of inaction.

Legal Responses from Environmental Organizations

Environmental and public health organizations have moved quickly to challenge the rescission of the endangerment finding in federal court, arguing that the decision is unlawful and threatens core climate protections. Coalitions of national groups—including the Environmental Defense Fund, American Lung Association, Natural Resources Defense Council, American Public Health Association, Union of Concerned Scientists, and others—have filed petitions for review in the U.S. Court of Appeals for the D.C. Circuit, which has long been the primary venue for Clean Air Act litigation. Several lawsuits also include or are supported by state attorneys general, who contend that the rollback harms their residents, economies, and sovereign interests by increasing climate-related risks within their borders.

These challengers argue that the EPA’s action violates both the Clean Air Act and the Administrative Procedure Act (APA). By rescinding the finding without a scientifically grounded rationale, plaintiffs say EPA is acting in a manner that is “arbitrary and capricious,” a key APA standard that prohibits agencies from ignoring evidence, reversing prior positions without reasoned explanation, or relying on impermissible considerations.

Legal filings emphasize that independent agencies exist precisely to align federal power with the best available science and expert judgment, especially where Congress has delegated complex, technical decisions to specialized bodies like EPA. Critics of the rescission note that Congress lacks the technical capacity and political bandwidth to continually reassess evolving climate science, which is why the Clean Air Act instructs EPA to make endangerment determinations and to update its regulations through notice‑and‑comment rulemaking. The lawsuits therefore argue that the Trump administration’s claim that EPA “overreached” in regulating greenhouse gas emissions under Section 202 of the Act misreads both the statute and Supreme Court precedent, which explicitly recognized EPA’s authority—and, once endangerment is found, its obligation—to act.

Central to these legal challenges is the charge that the rescission disregards “mountains of scientific evidence” documenting the dangers of greenhouse gas pollution. Plaintiffs assert that EPA cannot lawfully discard decades of peer‑reviewed research and its own prior findings without confronting that record and offering a coherent, evidence‑based explanation. Doing so, they contend, violates fundamental administrative law principles requiring agencies to engage in reasoned decision‑making and to respond meaningfully to the factual record and public comments. In this way, the litigation frames the rollback not just as a policy dispute, but as a test of whether federal agencies must still respect science, statutory mandates, and the procedural safeguards that Congress built into modern regulatory governance.

Legal Implications and Court Proceedings

Legal challenges to the rescission of the endangerment finding will unfold over several years, with multiple pathways and risks for how courts might reshape environmental law in the process. Given briefing, argument, and opinion timelines, one realistic scenario is that the D.C. Circuit issues a decision but the case does not reach the Supreme Court before the end of the current administration’s term, leaving a potential opening for a new president and EPA leadership to reverse course or narrow the impact of the rescission through new rulemaking.

Historically, courts have treated challenges to environmental regulations through the lens of administrative law: they do not rewrite policy themselves but ask whether the agency acted within its statutory authority and followed required procedures. In West Virginia v. EPA, the Court constrained EPA’s authority under the “major questions” doctrine, signaling skepticism when agencies claim broad power to make decisions of vast economic and political significance without clear congressional authorization. These precedents create a nuanced backdrop: courts have affirmed EPA’s basic authority to regulate greenhouse gases, while also warning that transformative regulatory schemes must rest on explicit statutory language.

Against this backdrop, several outcome scenarios emerge. In one, the D.C. Circuit rules against the rescission, finding that EPA’s new legal theory—that greenhouse gas emissions from vehicles and other sources fall outside the statute or are too “futile” to regulate—is inconsistent with Massachusetts v. EPA and inadequately justified, rendering the rule arbitrary and capricious under the Administrative Procedure Act. If the Supreme Court declines to review such a decision or affirms it by a narrow margin, the endangerment finding would be restored, much as the earlier 5–4 ruling in Massachusetts v. EPA preserved EPA’s climate authority over the objections of a prior administration.

A second, more fraught scenario is that the Supreme Court takes the case and upholds the rescission. In that event, the Court could reinterpret the Clean Air Act to conclude that EPA lacks authority to treat greenhouse gases as pollutants in this context, or that the statute gives the agency such broad discretion that it may effectively undo the endangerment finding without engaging with the underlying science. Such a decision would be precedent‑setting: once the Court has spoken, future presidents could not simply restore EPA’s authority by regulation alone. Instead, Congress would need to amend the Clean Air Act to explicitly reauthorize greenhouse gas regulation, an uphill political battle that could leave federal climate policy largely paralyzed for years.

These possibilities underline the stakes of the current litigation. The Trump administration has argued that EPA overreached in curbing greenhouse gas emissions, but the very design of modern environmental statutes assumes that independent agencies will align federal power with the best available science and expert judgment, precisely because Congress lacks the technical capacity and political agility to revisit complex scientific questions on a continual basis. EPA is also legally obligated to engage in extensive public deliberation—through notice‑and‑comment rulemaking, evidence-based findings, and reasoned explanations—for every major action it takes. The courts’ response to this rescission will therefore do more than decide one rule; it will signal how far agencies may go in abandoning established scientific determinations and how tightly the judiciary will police the boundary between politics and expert-driven environmental governance

What This Means for Everyday People

Rescinding the endangerment finding will show up in everyday life through dirtier air, higher risks from heat and wildfires, and more strain on local infrastructure. Many communities are likely to see more days with unhealthy air and extreme heat, which drive up emergency room visits and make some places harder and more expensive to live in.

Public health impacts will be especially severe for children, older adults, and people with asthma or other respiratory conditions. Weaker pollution controls mean more ground-level ozone and fine particles, which are tied to more asthma attacks, hospital visits, and missed days of work and school.

Even so, we still have meaningful ways to respond. Staying informed through reputable health and environmental organizations, watching local air quality alerts, and weighing in on proposed projects and rules can help shape local conditions. Inside Climate News is a great resource to stay updated on environmental news. Voting in every election and supporting groups that mobilize environmental voters are among the most powerful steps we can take, because decisions like rescinding the endangerment finding ultimately come from elected leaders. Organizations such as Vote.Org have all the information you need to register and vote in one place.