The US Environmental Protection Agency (EPA) turns 50 this year, but scientists and environmentalists see little reason to celebrate. In the middle of a global pandemic that is making world leaders scramble to protect citizens and restart economies, the agency’s leadership is pressing forward with controversial efforts to roll back environmental regulations and fundamentally alter the way in which science is used to craft policy.

In the past month alone, the agency has dialled down regulations on automobile emissions and fuel efficiency put in place under former president Barack Obama; it has weakened rules on mercury and other pollutants emitted by power plants; and it has shied away from strengthening standards to reduce fine-particle air pollution.

“This is an extremely aggressive agenda,” says Betsy Southerland, who spent more than three decades as an EPA official before retiring in protest against the current administration’s policies in 2017. By Southerland’s latest tally, the EPA has targeted more than 80 rules for revision or elimination in just over three years, without providing any evidence that the underlying science has changed.

But she and many others think that this is just the beginning of a regulatory overhaul that could hamstring future administrations’ attempts to craft health and environmental safeguards. Here, Nature looks at three recent decisions and two pending policy changes that could have a lasting impact.

Two rollbacks on emissions

At the end of March, President Donald Trump's administration finalized a plan to scale back targets for automobile-emissions reductions from 5% per year to 1.5%, a change that the EPA acknowledges could result in an extra 867 million tonnes of carbon dioxide being released into the atmosphere by vehicles sold over the next decade.

In mid-April, the EPA released another rule, targeting Obama-era mercury-emissions standards for power plants. Although the agency left the original regulatory limits in place, it adjusted how the rules’ costs and benefits are calculated, weakening their economic justification. The original price tag reported for the 2011 regulation took into account health benefits from a reduction in particulate matter that would accompany cuts to mercury emissions.

Taking these out of the equation makes the rule seem more expensive, says David Spence, a political scientist and law scholar at the University of Texas at Austin. It also sets a precedent that could undermine the mercury rule and others.

Planned inaction on particulates

Even more alarming, public-health experts say, was a decision on fine-particle pollution that EPA administrator Andrew Wheeler announced in mid-April. In that case, the EPA went against the advice of its own staff and many academic scientists by leaving the current standards in place — in spite of evidence that reducing such pollution could save thousands of lives each year ¹ .

In a report issued last September , EPA staff charged with reviewing the literature cited epidemiological and other evidence that would support cutting the maximum allowed average level of fine particulate matter from 12 micrograms per cubic metre of air to between 8 and 10.

The regulatory process that prevented that change was tipped toward the interests of polluters from the outset, with little to no independent scientific oversight, says Christopher Frey, an environmental engineer at North Carolina State University in Raleigh. Frey formerly chaired the EPA’s scientific advisory committee on clean air, and was a member of a review panel for the issue that was disbanded in October 2018.

“Rather than focusing on protecting public health, EPA is on a misguided mission to protect the profits of regulated industries,” Frey says. “But it’s all based on a lot of misconceptions and assumptions rather than facts or evidence.”

The ongoing coronavirus pandemic has been shown ² to have a higher death toll in communities affected by air pollution.

Two changes to the rules of engagement

Looking ahead, it could become even more difficult to bring health data and other evidence to the policymaking table if the EPA moves forward with a pair of proposals that would alter how science is used and evaluated at the agency. First is a “transparency” rule that could restrict the use of public-health studies — including much of the epidemiological research that the agency has used to set particulate-pollution standards in the past.

A draft proposal states that if underlying data and models are not publicly available — which is often the case for private health-care data — the EPA could give them less weight or exclude them from consideration entirely when setting standards and conducting scientific assessments.

The EPA released a supplemental proposal to the rule in March, providing additional options for how to implement the rule and expanding its application to cover all research used to support agency rules. After an outcry from scientists and environmentalists who have accused the agency of pushing through the rules while the public is focused on the coronavirus crisis, the EPA extended the public comment period by one month, to May 18.

Precisely how the rule would work remains unclear, but scientists and public-health advocates say that the latest changes do not solve the fundamental problem, which is that the rule could effectively sideline mainstream epidemiological research and undermine public-health regulations. “It’s headed in the wrong direction, and it would apply to pretty much all of EPA’s major work,” says Michael Halpern, deputy director of the Center for Science and Democracy at the Union of Concerned Scientists, an advocacy group in Cambridge, Massachusetts.

A second proposal, currently pending review at the White House, would change how the agency evaluates the costs and benefits of environmental and public-health regulations, much as it did in its re-evaluation of the mercury-emissions standards. Many experts think that the proposed guidance — which could be released in the next few months — will seek to reduce the consideration of incidental and indirect benefits from proposed rules.

Taken together, the cost–benefit guidance and the transparency rules could help the Trump administration to justify removing regulations, and could hamper regulatory efforts by future administrations. These and other EPA decisions will inevitably be challenged in court, but scientists and environmentalists say that provides little solace. “They are rolling back progress, and we are losing time,” Halpern says.

Southerland watched multiple administrations come and go during her time at the EPA, and says the scale and speed of the Trump administration's assault on science-based regulations is unprecedented. In many cases, the EPA’s leaders aren’t even presenting new evidence to justify their decisions, she says. “That’s why they can move so fast: they just say, ‘We no longer agree with the science and the facts.’”