The Environmental Protection Agency (EPA) announced a proposal to repeal regulations that limit greenhouse gas emissions and mercury pollution from power plants, marking a significant reversal of Biden-era environmental policies.

The EPA’s proposal consists of two major regulatory changes:

1. Repeal of Greenhouse Gas Emissions Standards: The agency is proposing to eliminate all “greenhouse gas” emissions standards for the power sector under Section 111 of the Clean Air Act. This would effectively remove limits on carbon dioxide emissions from coal and natural gas power plants.
2. Weakening of Mercury and Air Toxics Standards (MATS): The EPA also proposed repealing certain amendments to the 2024 Mercury and Air Toxics Standards that were finalized during the Biden administration. This would revert to the 2012 standards and eliminate more stringent requirements for filterable particulate matter emission standards for coal-fired power plants, tighter mercury standards for lignite-fired power plants, and requirements to use continuous emissions monitoring systems.

Mercury is a potent neurotoxin that affects the nervous system and brain functions, particularly in infants and children. It can cause neurological problems including vision and hearing difficulties, delays in motor skills development, and lowered IQ points. Studies show that one in six women of childbearing age has enough mercury in her bloodstream to put her child at risk of health effects.

The 2012 MATS rule has been highly effective in reducing mercury pollution, with 2021 mercury emissions from coal-fired power plants 90 percent lower than pre-MATS levels. Since 2010, acid gas hazardous air pollutant emissions have been reduced by over 96 percent, and emissions of non-mercury metals – including nickel, arsenic, and lead – have been reduced by more than 81 percent.

According to the EPA, these proposals would save the power sector approximately $19 billion in regulatory costs over two decades for the greenhouse gas standards, or about $1.2 billion annually. The mercury standards rollback would save an additional $1.2 billion over the next decade, or about $120 million per year.

Central to this regulatory battle is the Clean Air Act, which serves as the legal backbone for the EPA’s authority to regulate emissions from power plants. The Act requires the EPA to set and periodically update standards for air pollutants that endanger public health or welfare. Both the Mercury and Air Toxics Standards (MATS) and the greenhouse gas emissions standards were established under the Clean Air Act—MATS through the National Emissions Standards for Hazardous Air Pollutants Program, and greenhouse gas rules under Section 111, which mandates performance standards for new and existing sources of air pollution.

Any move to repeal or weaken these regulations involves changing how the Clean Air Act is interpreted and enforced. Critics, including environmental groups and former EPA officials, argue that such rollbacks undermine the law’s core purpose: to protect public health and the environment. 

Environmental groups have vowed to challenge the proposals in court.