The U.S. Environmental Protection Agency should probably go ahead and change its name if it moves ahead with a proposed weakening of vehicle emission standards. Atop all the other questionable actions this once-proud agency has undertaken under chief Scott Pruitt, the attempt to reverse course on more than four decades of steady progress in air quality standards ranks as one of the worst.

Details of the plan could still change. A draft has been sent to the White House but is not final. That makes this a good time to sound the alarms, before the hard-won advances of recent years erode.

Just as a reminder of the “good old days,” in the early 1970s the average American passenger car got about 13 miles per gallon. The pollutants from those hungry guzzlers produced smog that could make the sunniest days seem overcast. When the government instituted standards to improve fuel economy and curb pollutants, auto manufacturers complained mightily.

But the federal government persisted. Whether led by Democrats or Republicans, it continued to push for higher standards. Leaders knew that saving fuel would make this country more energy secure, while cleaner air would improve and save American lives. As a bonus, the higher standards drove technology innovations undreamed of in the 1970s.

President Barack Obama, in a 2011 agreement backed by rigorous scientific and public health evidence and joined by more than a dozen of the largest automakers, set a goal of about 50 mpg by 2025. With the change of administration, auto manufacturers have reverted to type, complaining about the regulatory costs and asking the Trump administration for relief. Though he lacks evidence for his assertions, Pruitt obligingly has declared that goal unreachable and too onerous. He has not yet produced an alternative standard, and there appears to be no timetable for one.

That sets the stage for backsliding, said John Linc Stine, commissioner of the Minnesota Pollution Control Agency. “One principle holds true across clean water and clean air legislation,” he said. “Prevention of backsliding. Once you make progress, you further it. You do not let it slide back.” Pruitt’s action, he said, “sets up a different rationale.” Once established in air quality, the same rationale might be applied to clean water standards, Stine said, leading to degradation instead of improvement.

Minnesota needs strong federal standards on air and water quality. It cannot, on its own, require cars to meet a higher standard.

“States have come a long way and made dramatic progress,” Stine said. “I want to see that progress sustained. When you weaken national standards, you’re harming states that want to do better.”