A little-known pollution rule keeps the air dirty for millions of Americans.
by Molly Peterson, Dillon Bergin, Emily Zentner and Andrew Witherspoon, MuckRock
A legal loophole has allowed the U.S. Environmental Protection Agency to strike pollution from clean air tallies in more than 70 counties, enabling local regulators to claim the air was cleaner than it really was for more than 21 million Americans.
Regulators have exploited a little-known provision in the Clean Air Act called the “exceptional events rule” to forgive pollution caused by “natural” or “uncontrollable” events – including wildfires – on records used by the EPA for regulatory decisions, a new investigation from The California Newsroom, MuckRock and the Guardian reveals.

In addition to obscuring the true health risks of pollution and swerving away from tighter control on local polluters, the rule threatens the potency of the Clean Air Act, experts argue, at a time when the climate crisis is posing an unprecedented challenge to the health of millions of Americans.
Where the EPA — the U.S. department monitoring air quality — has agreed to exclude bad air days from analysis, “we may have a sort of stable, relatively rosy picture when it comes to our regulatory world in terms of air-quality trends,” said Vijay Limaye, a climate and health epidemiologist at the Natural Resources Defense Council, a nonprofit advocacy group.
The truth is more complicated, and the air dirtier.
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