EPA rolls back mercury limits and interstate pollution rules

EPA Administrator LZLee Zeldin announced the MATS rollback on February 20, 2026, at LG&E's Mill Creek Generating Station in Louisville, 🐴Kentucky — a 1,465-megawatt coal plant sitting next to the 🌰Ohio River. The rollback repeals Biden's 2024 updates that had tightened mercury, arsenic, and lead emission limits. It also eliminates the requirement that power plants use continuous emissions monitoring systems to track how much pollution they actually release.

Under the repealed 2024 standards, coal plants faced stricter limits on filterable particulate matter and had to install monitoring equipment. The rollback returns plants to the original 2012 MATS standards set under the Obama administration. Coal-burning power plants can now emit more than twice as much mercury as they could under the tighter 2024 limits, according to an analysis published in Eos.

EPA claims the rollback will save coal companies $670 million between 2028 and 2037 by eliminating what it calls 'unwarranted compliance costs.' EPA Deputy Administrator DFDavid Fotouhi said the move 'rights the wrongs of the last administration's rule.' But environmental groups point out that the 2024 MATS updates delivered health benefits worth billions more than their costs — the original 2012 MATS alone prevented up to 11,000 premature deaths annually.

The Good Neighbor Rule rollback, proposed in January 2026, targets a different problem: ozone pollution that drifts across state lines. Under the Clean Air Act, states must submit plans showing they won't send harmful levels of smog-forming pollution into neighboring states. The Biden EPA had rejected plans from 🏈Alabama, 🌵Arizona, 🐴Kentucky, 🎸Mississippi, 🦆Minnesota, 🎰Nevada, 🌶️New Mexico, and 🎸Tennessee as inadequate and imposed federal requirements instead.

Zeldin's EPA is now reversing course, proposing to approve those eight state plans and accept them as sufficient. EPA also withdrew error-correction actions for 🌽Iowa and 🌻Kansas. If finalized, these states won't face any additional federal requirements to cut ozone-forming pollution — even though downwind states like 🦞Connecticut, 🗽New York, and 🧀Wisconsin still struggle to meet air quality standards partly because of pollution blowing in from upwind.

🏛️Massachusetts Attorney General MHMaura Healey filed a lawsuit with attorneys general from 20 other states, the 🏛️District of Columbia, and the cities of Baltimore, Chicago, and 🗽New York challenging the MATS rollback. Earthjustice attorney NMNicholas Morales called the repeal 'an attack on public health.' The legal coalition argues EPA violated the Clean Air Act by removing protections the agency itself determined were necessary to protect public health.

Mercury is a potent neurotoxin. It crosses the placenta and can damage a developing baby's brain, causing learning disabilities, memory problems, and delayed development. One in six pregnancies in the United States involves women with too much mercury in their bodies, according to EPA data. Coal-fired power plants are the single largest human-caused source of mercury pollution in the United States.

🐴Kentucky's own mercury emissions dropped from 1,563 pounds in 2010 to 163 pounds in 2023 — a 90% reduction driven by MATS compliance. The rollback puts those gains at risk. Environmental advocates warn that weakening both mercury standards and interstate pollution rules simultaneously creates a compounding effect: more toxic pollution from individual plants, plus less accountability for pollution crossing state borders.