Air Alliance Houston et al. v. Donald Trump et al.
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Emissions rising from the dual-fired W.A. Parish Generating Station in Fort Bend County, Texas
In April and July 2025, President Trump issued proclamations unilaterally exempting roughly one-third of the nation’s coal-fired power plants from the 2024 Mercury and Air Toxics Standards (MATS). These standards protect Americans from exposure to dangerous pollutants like mercury, arsenic, and nickel, which are known to increase health risks, including cancer, birth defects, and developmental harms in children.
The 2024 MATS built on previous standards that reduced emissions of mercury by 90 percent and other toxic metals by 80 percent, helping to save up to 11,000 lives and resulting in $33 million in health benefits per year. The updated MATS standards would further reduce mercury emissions by 9,500 pounds and arsenic and other toxics by 49 tons over 10 years. The U.S. Environmental Protection Agency (EPA) estimated that the 2024 rule would yield $79 million in monetizable health benefits in 2028 alone.
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To exempt these coal plants, the Trump administration exploited a never-before-used provision of the Clean Air Act, Section 112(i)(4), which provides authority to exempt sources from a hazardous air pollutant standard if the president determines that the technology to implement the rule is “not available” and that an exemption is in the national security interests of the United States. But the EPA’s own evidence shows not only that the technology to implement the more stringent 2024 standard is widely available but also that it is installed and in use by most of the industry—including a majority of the facilities that received exemptions. In fact, the EPA admitted in a proposed rulemaking this summer that all but one facility could meet the revised arsenic and other toxics standards using existing controls.
The Trump administration’s exemptions have nothing to do with technological availability or national security. Instead, the exemptions are a giveaway to the coal industry. To receive an exemption, coal plants merely had to send the EPA an email requesting their free pass. Ultimately, 71 coal plants got their wish: Thanks to President Trump, they can avoid the costs of installing pollution-control devices—and even avoid the costs of running the pollution-control devices they already have—to the detriment of people who breathe the air around them. And in the meantime, the Trump administration’s EPA is attempting to fully repeal the 2024 MATS standards, which the agency had just concluded last year were technologically feasible and cost-justified.
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This is not only dangerous—it is illegal. It is undemocratic. President Trump has exempted these facilities and sacrificed the health of the people and communities impacted by these toxic emissions, without any public input. No president has ever before asserted the authority to excuse industry en masse from regulations that the EPA issued just a year ago with the benefit of an extensive scientific and technical record and public notice and comment. But President Trump has.
So NRDC and our partners—Air Alliance Houston, Center for Biological Diversity, Citizens for Pennsylvania’s Future, Clean Air Council, Downwinders at Risk, Environmental Integrity Project, Environmental Law & Policy Center, Montana Environmental Information Center, and the Sierra Club—have filed suit in federal court in Washington, D.C., to challenge those illegal exemptions.
In September 2025, the court stayed our litigation for six months, relying on the EPA’s assertion that it would complete its repeal of the 2024 MATS rule by the end of 2025. NRDC and our partners will continue to vigorously challenge these illegal exemptions, as well as the EPA’s separate planned rollback of this important rule.
But the Trump administration hasn’t stopped with MATS. In July, President Trump issued similarly sweeping proclamations exempting the entire taconite iron-ore processing industry, 52 synthetic organic chemical manufacturing facilities, and 41 medical-sterilizing facilities that emit the highly carcinogenic chemical ethylene oxide. As with MATS, the EPA has simultaneously announced that it will reconsider the hazardous air pollutant rules for those source categories.
Case Documents
NRDC's Petition for Review in the D.C. Circuit, June 12, 2025 (Air Alliance Houston et al. v. Donald Trump et. al) (PDF) NRDC's Complaint in the District Court of D.C., June 12, 2025 (Air Alliance Houston et al. v. Donald Trump et. al) (PDF) NRDC's Statement of Issues in the D.C. Circuit, July 14, 2025 (Air Alliance Houston et al. v. Donald Trump et. al) (PDF) EPA's Motion to Hold Case in Abeyance in the District Court of D.C., August 5, 2025 (Air Alliance Houston et al. v. Donald Trump et al.) (PDF) NDRC's Opposition to Abeyance Motion in the District Court of D.C., August 19, 2025 (Air Alliance Houston et al. v. Donald Trump et al.) (PDF) EPA's Reply in Support of Abeyance in the District Court of D.C., August 26, 2025 (Air Alliance Houston et al. v. Donald Trump et al.) (PDF) Minute Order Granting Abeyance, September 3, 2025 (Air Alliance Houston et al. v. Donald Trump et al.) (PDF) NRDC's Motion for Reconsideration of Order Granting Abeyance in the District Court of D.C., October 24, 2025 (Air Alliance Houston et al. v. Donald Trump et al.) (PDF) Consent Motion to Hold in Abeyance, March 17, 2026 (Air Alliance Houston et al. v. Donald Trump) (PDF)RELATED COURT BATTLES
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