The Environmental Protection Agency (EPA) last month proposed eliminating two recent rules that would have protected public health and helped address climate change.

We are a practicing pulmonologist who treats and studies the health effects of air pollution and a lawyer who has worked to develop legally durable regulations to address climate and environmental harms. While we come to this issue from different disciplines, we share a common concern: These proposals, if finalized, would undermine progress on air pollution and climate change, which is an unprecedented human health crisis.

Which regulations would be repealed?

The 2024 Mercury and Air Toxics Standards (MATS) set more stringent emission limits on hazardous air pollutants like mercury and other toxic metals from coal- and oil-fired power plants. Compliance with these standards would have phased in over the next few years. The Trump EPA is proposing to repeal this rule even though over 90% of plants already meet the more protective standard. The EPA also proposes to eliminate the requirement for continuous emissions monitoring, making it easier for higher emissions to go undetected between compliance tests and allowing plants that burn lignite coal to emit twice as much mercury as non-lignite plants.

The EPA also wants to eliminate the 2024 Carbon Pollution Standards for power plants, which set the nation’s only enforceable limits on greenhouse gas (GHG) emissions from new and existing fossil fuel-fired power plants. The EPA is arguing, for the first time, that power plants do not “contribute significantly” to dangerous GHG pollution under the Clean Air Act, even though the sector represents the largest stationary source of GHG emissions in the United States. The implications are drastic. If the EPA were to finalize this approach, it would prevent GHG emission limits on power plants and any other stationary sources under the Clean Air Act.

Will these changes survive legal challenges?

If the final rules—expected as soon as the end of this year—are similar to what the EPA has proposed, they will have significant legal vulnerabilities.

The Clean Air Act requires the EPA to update hazardous air pollutant standards based on technology improvements and to regulate power plants’ GHG pollution if those emissions endanger public health or welfare. Eliminating these rules would diverge from longstanding agency practice.

For example, it will be hard for the EPA to argue that plants cannot achieve the more stringent standard when 90% already are. The EPA also fails to consider setting moderately less stringent standards. Courts may reject the EPA’s all-or-nothing approach if they determine the agency failed to undertake a reasonable analysis of alternatives.

Additionally, by finding that power plants’ GHGs do not significantly contribute to air pollution, the proposal contradicts decades of EPA findings and the EPA’s long-standing interpretation of the Clean Air Act, including by the first Trump administration. In doing so, the agency relies on reasoning similar to what the Supreme Court rejected in Massachusetts v. EPA (2007), when it ruled that greenhouse gases are pollutants under the Clean Air Act. 

What would the repeals mean for public health?

EPA’s mission is “to protect human health and the environment,” yet both repeals focus on cost-savings for industry, while downplaying and even failing to evaluate the substantial health and environmental benefits of improved air quality—such as reduced neurological harm from mercury and avoided hospitalizations.

Power plants are often located near low-income neighborhoods and communities of color, who are exposed to higher levels of pollutants including particulate matter, nitrogen dioxide and toxic metals. People living near coal-fired power plants have been found to have higher hospitalizations for respiratory disease, and pollution from coal-fired power plants is twice as deadly as air pollution from other sources. Rolling back standards and allowing power plants to pollute at higher levels further entrenches these environmental injustices.

If MATS is weakened, more mercury and other hazardous air pollutants will be emitted from power plants. These pollutants are especially dangerous for infants and children, including those exposed in utero, as developing brains are highly vulnerable to toxic exposure, potentially resulting in permanent effects on brain function. Even at low doses, mercury can reduce IQ. The MATS standard, as written, is also projected to reduce fine particulate matter (PM2.5) by 770 tons in 2028, which stands to benefit heart and lung health, pregnancy outcomes, and even mental health and brain development.

Eliminating GHG rules will encourage older and higher-emitting coal-fired power plants to continue to operate, leading to more deaths from respiratory and cardiovascular illness, more lost workdays, and higher healthcare costs. It also means more heat-trapping carbon pollution contributing to heat waves, wildfires, flooding, and the spread of infectious diseases, all of which put health at risk.  

The EPA justifies its repeals by pointing to cost savings for industry—but sidesteps the immense public health costs and burden of increasing exposure to toxic air pollution.

A dangerous shift in priorities

While the details of the rules may appear technical and legal, their impact is deeply personal: They determine whether your child breathes cleaner air, whether your community faces higher cancer and asthma rates, and whether our climate becomes increasingly unstable. The EPA’s mission is to protect human health and the environment. These proposals undermine that mission.

All perspectives expressed in the Harvard Climate Blog are those of the authors and not of Harvard University or the Salata Institute for Climate and Sustainability. Any errors are the authors’ own. The Harvard Climate Blog is edited by an interdisciplinary team of Harvard faculty.