April 21, 2026 update: On March 17, 2026, EPA proposed rescinding several of the EtO emissions standards for commercial sterilizers it finalized in 2024. Read EELP’s quick take explaining the proposed rescissions.
On April 5, 2024, EPA finalized a rule to significantly reduce the emissions of ethylene oxide (EtO) from commercial sterilization facilities under Section 112 of the Clean Air Act (CAA). The rule was immediately challenged by both environmental groups and industry. The Trump administration said it will reconsider the 2024 rule and invited industry to seek exemptions.
EtO is a potent carcinogen. While EtO emissions from sterilization facilities have been regulated since 1994, prior requirements did not apply to several significant sources of EtO, including fugitive emissions (also called “room air emissions”). As a result, communities that live near these facilities — who are disproportionately low-income and communities of color — have suffered from a significantly higher rate of cancer than the rest of the country. If the 2024 final rule were to take effect, EPA anticipated it would reduce annual EtO emissions from commercial sterilizers 90% by 2027 by increasing the stringency of emissions standards, regulating fugitive emissions, and requiring consistent monitoring to ensure compliance with the new standards.
This paper summarizes EPA’s EtO final rule for sterilization facilities, discusses the significance of regulating EtO emissions for fenceline communities, and examines how the pollutant has historically been regulated. It also details the rule’s requirements, including changes to prior regulations, and looks at the litigation challenging it and the Trump administration’s anticipated effort to roll it back.
At a May 14 panel sponsored by the Salata Institute for Climate and Sustainability, Harvard climate faculty shared what they have learned from the first four months of the Trump administration, what worries them the most about his attacks on climate research and policy, and what they are watching in the months ahead.
For me, there are five pillars in how we approach climate policy in the United States. Donald Trump is attacking all five.
1. International engagement
The U.S. plays a crucial role in global climate negotiations. Our presence — or absence — on the international stage influences cooperation on emissions reductions, technology transfers, and adaptation financing. Abrupt shifts in policy weaken trust and disrupt progress. The president has announced that the U.S. will withdraw from the Paris Agreement.
2. Domestic regulation
The president is challenging federal and state environmental and clean energy rules in a variety of ways, including with executive orders. In April, Trump directed the Attorney General to investigate state-level clean energy policies, with the goal of undermining any perceived threat to the administration’s commitment to fossil-fuel dominance.
At the same time, the administration instructed agencies like the Federal Energy Regulatory Commission (FERC) to deploy emergency powers to prop up coal-fired power. The president also signed orders directing agencies to roll back environmental rules without the usual public notice or comment process. That threatens the bedrock principle of transparent, lawful government.
Another example of the administration’s attack on state-level regulation is the battle over California’s Clean Air Act waivers. That special authority granted to the state by Congress allows California to apply to EPA for a “waiver” of federal preemption to set its own vehicle emissions standards, which other states may follow. California’s role is important nationwide because the state has been a bulwark against federal backsliding, by continuing to spur progress toward cleaner technologies in the transportation sector even when federal rules are weakened. Now, Congress appears poised to nullify the most recent waivers, using a law that allows it to void federal rules using a fast-track, filibuster-proof process. Although these individualized waiver grants have never been treated as rules before, Congress is considering classifying them as rules now, over the objection of both the General Accountability Office and the Senate Parliamentarian. The House has already voted to disapprove them; the Senate’s decision to do so would set a far-reaching precedent.
3. Industrial policy
When Congress invests in clean energy infrastructure, transportation, and manufacturing, as it did by passing the Inflation Reduction Act and the Infrastructure Investment and Jobs Act during the Biden administration, it’s pursuing an industrial policy approach to climate change. The Greenhouse Gas Reduction Fund, for instance, was designed to inject billions into decarbonization and efficiency upgrades, such as clean school buses and more efficient buildings. Yet, early on, the Trump administration froze much of this funding, even though it was congressionally appropriated and fully obligated to grantees. Judges have intervened to unfreeze some grants, but the broader landscape remains mixed as challenges move through the courts. The current uncertainty and instability is bound to have a chilling effect on grantees and their private-sector partners, and will undermine confidence in government-backed climate efforts.
4. Climate science and research
The administration has also taken aim at the scientific research behind climate policy. One major example is the pending reconsideration of the Endangerment Finding – the scientific and legal basis for regulating greenhouse gases under the Clean Air Act. If the administration were to rescind the endangerment finding, there would no longer be a legal foundation to set federal greenhouse gas standards. This would remove the government’s most important tool for limiting climate pollution.
5. The role of the private sector
Finally, the private sector is essential to driving clean energy innovation and addressing climate risk. And it too depends on regulatory consistency and predictability from government. Abrupt funding freezes, shifting rules, and chaotic policy gyrations have sown uncertainty and undermined confidence, which inhibits investment and innovation across energy, transportation, and tech. The administration has also threatened private sector climate coalitions with anti-trust investigations, chilling private sector coordination to promote net-zero commitments.
What’s reversible?
Many people ask me whether these rollbacks and reinterpretations are permanent. Executive orders are not law. The normal rule is: What a president can do with the stroke of the pen, the next president can undo with the stroke of the pen. But that’s not exactly right in this instance because of the extent to which this administration is changing the status quo with utter disregard for the normal legal constraints. The administration is swinging for the fences and clearly daring the courts to stop them. And by the time the law catches up with them, conditions on the grounds will have significantly shifted. Re-building government capacity is harder than tearing it down. Attracting new private investment is harder than scaring it off. So reversing some things will be much harder.
More broadly, the administration is doing lasting harm to the government’s institutional capacity and to democratic accountability. When you don’t have access to science and information; when long-serving independent experts are cut out of government policymaking and replaced by loyalists; when expertise is downgraded, and political support or affiliation is upgraded within the agencies; when you can’t access the data necessary to assess whether public health outcomes are worse or better – when all these things happen, it becomes harder to hold the government to account.
Updates: On Sept. 14, 2026, the director of the Fish and Wildlife Service circulated a memo interpreting the scope of “take” following the harm rescission. The director states that following Justice Scalia’s interpretation, take will be interpreted to mean only “an affirmative act that is intentionally and purposefully directed at a particular animal.” This interpretation drastically narrows the ESA’s ability to protect species.
On July 14, 2026, the Trump administration finalized its rescission of harm under the Endangered Species Act. In justifying the elimination of this 50-year-old regulatory definition, the administration took a highly unusual approach: it rejected Supreme Court precedent in Sweet Home upholding the harm definition and explicitly adopted Justice Scalia’s dissenting opinion in that case. The final rule states, “We adopt Justice Scalia’s rationale as articulated in Sweet Home and conclude that the Services’ regulatory definitions are unlawful, notwithstanding the Court’s prior upholding of the regulatory definition under Chevron deference.” While some other Trump rules have tried to sidestep Supreme Court precedent, for example, the endangerment finding repeal, we have not seen the administration flatly reject a Supreme Court decision in its legal rationale for a deregulatory action in this way. We will see how this aggressive approach fares in court.
The Endangered Species Act of 1973 (ESA) makes it unlawful for any person to “take” endangered species[1] and defines “take” to mean to “harass, harm, pursue,” “wound,” or “kill.”[2] In implementing regulations, the Fish and Wildlife Service and the National Marine Fisheries Service (“the Services”) have for over 40 years defined “harm” to include “significant habitat modification or degradation where it actually kills or injures wildlife.”[3] The Services used a broader regulatory definition of “harm” prior to 1981.[4] Habitat loss is a major threat to species across the United States.
On April 17, 2025, the Services proposed rescinding the longstanding definition of “harm” under Section 9 of the Endangered Species Act. The Services explained in the proposal that the definition of “harm,” which currently includes habitat loss and modification, “runs contrary to the best meaning” of the statute.
In a 1995 opinion written by Justice Stevens and joined by Justices O’Connor, Kennedy, Souter, Ginsberg, and Breyer, Babbitt v. Sweet Home Chapter of Communities for a Great Oregon, the Court held that “significant habitat modification or degradation that actually kills or injures wildlife” could reasonably be considered part of “harm” to species under the ESA.[5] This decision relied in part on Chevron Step 2 to bypass the underlying question of whether “take” as defined in the statute could include this regulatory definition of “harm.” The Court explained that the statutory definition of “take” (which includes “harm”) was ambiguous and the way the Fish and Wildlife Service defined “harm” in regulation was reasonable for a variety of reasons, allowing the Court to apply Chevron deference.
Now, the Trump administration uses Justice Scalia’s dissent in Sweet Home to conclude that the current regulations “do not match the single, best meaning of the statute,” arguing that “the regulations’ interpretation of the statutory language violates the noscitur a sociis canon [suggesting that a word is defined in context of surrounding words], did not properly account for over a thousand years of history, and is inconsistent with the structure of the ESA.” The Services states that no replacement definition is needed, as the statute already defines “take” and further explanation of the term “harm” “is unnecessary in light of the comprehensive statutory definition.”
The Services acknowledge that the 2024 LoperBright Enterprises v. Raimondo decision[6] overturning Chevron did not call into question cases previously decided under the Chevron framework. Nonetheless, they explain that rescinding the definition “on the ground that it does not reflect the best reading of the statutory text . . . would not only effectuate the Executive Branch’s obligation to ‘take Care that the Laws be faithfully executed,’ but would also be fully consistent with Sweet Home.”
In the proposal, the Services request public comment on whether there are “legitimate reliance interests” on the current regulations, noting possible environmental, aesthetic, and property rights interests, but stating that “we believe that reliance interests likely will be outweighed by the constitutional interest in repealing regulations that do not reflect the best reading of the statute.” The Services also invite the public to comment on whether and how NEPA analysis should apply. Comments are due by May 19.
This proposed rollback is one step in the Trump administration’s aggressive deregulatory agenda, laid out in a series of executive orders. The administration signaled in an April memorandum and fact sheet that it plans to use the Loper Bright decision to justify rolling back rules that it believes are not grounded in the “best meaning” of a statute. This proposed rule uses the pretext of Loper Bright to justify a rescission despite the fact that Loper Bright is not intended to unsettle past caselaw decided using the Chevron framework. Loper Bright applies to legal interpretations by courts, expressly limiting agencies’ authority to interpret the law.
The proposal ignores abundant scientific evidence that habitat loss harms threatened and endangered species, but it does not come as a surprise. Rolling back this definition has long been a priority for some organizations and was expected after Loper Bright.
We will be watching how the Services respond to commenters in the final rule, how courts view the Services’ justification in the final rule, and the practical impact of the final rule on habitat protection.
[1] 16 U.S.C. § 1538. [2] 16 U.S.C. § 1532. [3] “Harm in the definition of ‘take’ in the Act means an act which actually kills or injures wildlife. Such act may include significant habitat modification or degradation where it actually kills or injures wildlife by significantly impairing essential behavioral patterns, including breeding, feeding or sheltering.” 50 C.F.R. § 17.3; 50 C.F.R. § 222.102. [4] As the Services explain, the earlier regulatory definition could have been read to include habitat modification or degradation without evidence of death or injury to species 46 FR 54748-01. [5]Babbitt v. Sweet Home Chapter of Communities for a Great Oregon, 515 U.S. 687 (1995). [6]Loper Bright Enterprises v. Raimondo, 603 U.S. 369, 394 (2024).
Warning: Undefined array key "post_type_name" in /nas/content/live/harvardeelp/wp-content/themes/eelp_2024/template-parts/content.php on line 21
Warning: Undefined array key "term_link" in /nas/content/live/harvardeelp/wp-content/themes/eelp_2024/template-parts/content.php on line 25
Warning: Undefined variable $post_type_name in /nas/content/live/harvardeelp/wp-content/themes/eelp_2024/template-parts/content.php on line 38
Warning: Undefined variable $post_type_name in /nas/content/live/harvardeelp/wp-content/themes/eelp_2024/template-parts/content.php on line 42
Warning: Undefined variable $post_type_name in /nas/content/live/harvardeelp/wp-content/themes/eelp_2024/template-parts/content.php on line 46
Warning: Undefined variable $post_type_name in /nas/content/live/harvardeelp/wp-content/themes/eelp_2024/template-parts/content.php on line 80
Environmentalists’ worst fears met and surpassed in Trump’s first 100 days
