Stacey Vanek Smith: Power plants and air regulators are working through the implications of a new court ruling this morning. The decision shot down an air pollution rule from the Environmental Protection Agency. Now regulators have to go back to the drawing board.

From the Marketplace Sustainability desk, Scott Tong reports.

Scott Tong: A federal appeals court ruled EPA overstepped its authority to regulate power plants. The issue is pollutants linked to asthma and heart disease. When the wind blows, people downwind suffer.

So EPA tried to force polluters upwind to buy smokestack controls, or run less often.

John Walke: The court found that EPA had required too much pollution reduction from those power plants.

That’s John Walke at the Natural Resources Defense Council.

EPA says the rule would have cost industry almost a billion dollars to comply. But it tallied nearly $300 billion in health benefits. Still, industry fought it, and won. So now, an older rule applies, but a court’s found that too soft. Hello, Goldilocks?

Walke: EPA has been whipsawed between two court decisions now. One in 2008 ruling that EPA had not enough to protect the public. And one that EPA had done too much to protect the public.

EPA can go back to court, or craft a new rule. Either way, many think a number of coal plants may close anyway – due to competition from natural gas.

In Washington I’m Scott Tong for Marketplace.