It's a win for advocates of healthier air for New York State residents.  The U.S. Court of Appeals DC Circuit’s decision in New York et al. v. EPA, No. 19-1019, sustains New York’s challenge to a Trump-era EPA rule that would have gutted standards regulating ozone emissions:

New York's Attorney General Letitia James released the following statement in response to the court's decision:

“New Yorkers have a right to clean, healthy air. But the fact is, over two-thirds of New Yorkers regularly breathe unhealthy air due to smog pollution. We will continue our battle to compel the Trump Administration to follow the law in our effort to fight this public health hazard and to uphold New Yorkers’ legal right to clean, healthy air.” 

In the Close-Out Rule, EPA said it had sufficiently addressed its obligation under the Clean Air Act’s “good neighbor provision” to prohibit upwind ozone pollution that substantially interferes with the ability of downwind states like New York to meet the 2008 ozone standard of 75 parts per billion. But the Court agreed that was not enough. On September 13, the DC Circuit in Wisconsin v. EPA struck down a key part of a related rule known as the Cross-State Air Pollution Rule Update because it allowed continued upwind emissions beyond downwind states’ next applicable attainment deadlines. Similarly here, the Court vacated the Close Out Rule because EPA failed to require upwind states to reduce their pollution by New York’s next applicable attainment deadline in 2021.

New York led a group of state and local governments including Connecticut, Delaware, Maryland, Massachusetts, New Jersey, and the City of New York in challenging the Close-Out Rule. The state petitioners were also joined by several private groups in challenging the rule.