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The obscure rule that keeps cities under federal pollution limits


The people responsible for improving air quality are increasingly turning to a little-known rule to meet federal clean air standards for millions of Americans, and they do so even as wildfire smoke becomes more common. That's the finding of a recent investigation from the California Newsroom, MuckRock and the Guardian. Lead reporter Molly Peterson from the California Newsroom joins us. Molly, thanks for being with us. You're welcome. What is this rule called the exceptional events rule?

MOLLY PETERSON, BYLINE: Yes. It's tucked into the landmark Clean Air Act, and it lets local regulators exclude bad air days if they can tie them to events that are uncontrollable or defined as natural by the Environmental Protection Agency. That includes volcanoes and dust storms. And this is the one we're really paying attention to - wildfires.

SIMON: And what did your reporting find?

PETERSON: Well, we found that more places are using this rule to forgive more and more days of pollution as climate change sets the stage for bigger and bigger wildfires. California has traditionally used this rule more than anybody else. But it's not just the West Coast. More than 21 million people in the United States live in places where regulators have used this rule, from Washington state to Louisiana and Baltimore.

SIMON: Can you give us an example?

PETERSON: Well, let me take you to southeast Michigan. In 2022, Detroit had enough smoggy days that the region might miss multiyear federal air goals for ozone. If that happened, Michigan would need tighter rules on everything from auto assembly plants to print shops and a vehicle inspection program - not very popular in the Motor City. Michigan argue that two of these smoggy days were influenced by Canadian wildfires last summer. And because EPA agreed, the state avoided adding rules that businesses oppose. And, of course, just this summer, much of the U.S. East Coast suffered effects of more Canadian wildfires. We know from federal data that 23 states have signaled the possibility of filing exceptional events around that, including Minnesota, Texas and the Carolinas.

SIMON: What does the EPA say about this rule in practice?

PETERSON: When they answered us in writing, EPA maintained that these policies are a part of the law - the Clean Air Act - and that all of the forgiven, exceptional events data still exists, like for health researchers to find and use. What they don't like is calling it a loophole. But we heard that a lot. Regulators and other sources called it a magic wand, an escape hatch, a get-out-of-jail-free card.

SIMON: Well, what are the possible repercussions of increasingly relying on this rule?

PETERSON: The Clean Air Act has for over 50 years saved lives and millions of dollars by controlling pollution at its source, at tailpipes and smokestacks. The biggest problem, according to public health experts and advocates, is that forgiving bad air on paper doesn't change the fact that smoke can be harmful. I talked with health scientist Vijay Limaye, who works for the Natural Resources Defense Council.

VIJAY LIMAYE: So we may have a sort of stable, relatively rosy picture. But the true conditions on the ground in terms of the air that people are breathing in, you know, day after day, week after week, year after year is increasingly an unhealthy situation.

PETERSON: Even so, regulators around the U.S. straight-up tell us and the EPA that they're going to lean on this rule more, not less, in the years ahead.

SIMON: Molly, what are you watching for as this continues to play out?

PETERSON: The Clean Air Act wasn't written in an age of climate change like a lot of our environmental laws. It didn't anticipate the dramatic increase in wildfire smoke we're seeing in the skies now. You can't put scrubbers on wildfires the way you can on coal plants. Here's law professor Michael Wara. He's at Stanford's Woods Institute for the Environment.

MICHAEL WARA: What exceptional events determinations seem to show is a poorer and poorer fit between the policy we have and the problems it's trying to solve.

PETERSON: Wara calls it a warning light on the dashboard for the Clean Air Act. Climate change is making air pollution worse. Regulators say pretty much all they can do is warn people about all of this, unless the law is changed.

SIMON: California Newsroom's Molly Peterson. Thanks so much.

PETERSON: You're welcome.

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Scott Simon is one of America's most admired writers and broadcasters. He is the host of Weekend Edition Saturday and is one of the hosts of NPR's morning news podcast Up First. He has reported from all fifty states, five continents, and ten wars, from El Salvador to Sarajevo to Afghanistan and Iraq. His books have chronicled character and characters, in war and peace, sports and art, tragedy and comedy.