"California officials and clean air advocates are increasingly concerned the Trump administration may attempt to unravel a key program to drive down greenhouse gas emissions from automobile fleets while also jeopardizing the ability of California and other states to set pollution standards stronger than federal rules."

"The rescue of the planet’s protective ozone layer has been hailed as one of the great success stories of modern environmental regulation — but on Monday, an international team of 22 scientists raised doubts about whether ozone is recovering as expected across much of the world."

"Due to heavy fertilizer use, California's Central Valley is behind up to 41 percent of the state's emissions of nitrogen oxide — an air pollutant and climate-warming gas".

"A large proportion of California's nitrogen oxide—which can cause harmful ozone and a variety of health impacts—comes from heavy fertilizer use in the state's Central Valley, according to a new study.

"A federal court granted the Environmental Protection Agency (EPA) a victory Thursday, allowing regulators to give U.S. livestock producers more time to comply with a mandate on reporting emissions from animal waste."

"Ten U.S. states and the District of Columbia said Thursday they are challenging a decision by the Trump administration to drop a requirement that Harley-Davidson Inc (HOG.N) spend $3 million to reduce air pollution under settlement the Obama administration announced."

"Environmental Protection Agency (EPA) Administrator Scott Pruitt says he supports a unified national vehicle fuel standard, stoking state fears that the agency may do away with waivers allowing states to implement stronger standards."

"The U.S. Environmental Protection Agency said on Thursday it was withdrawing a provision of the Clean Air Act that requires a major source of pollution like a power plant to always be treated as a major source, even if it makes changes to reduce emissions."

"Two decades after its scheduled closure, a zombie garbage incinerator divides a working-class town in Massachusetts."