"SACRAMENTO, Calif. — A coalition of 11 environmental groups has sued the U.S. Environmental Protection Agency for revoking California’s authority to set tougher emission standards for cars and trucks than the federal government.

The federal government has allowed California to set its own emission standards since the 1970s because the state has the most cars on the road and struggles to meet air quality standards. Thirteen other states plus the District of Columbia follow California’s rules.

"US air pollution rules could be hugely insufficient in preventing deaths, experts are concluding from a new study of the likely causes of death of 4.5 million veterans."

"California on Friday broadened its effort to block the Trump administration from ending its authority to set greenhouse gas emission and fuel economy standards for cars and trucks."

"Environmental groups had been waiting nearly three years for the U.S. Environmental Protection Agency to comply with a federal judge’s orders to update Clean Air Act rules governing emissions of various toxic chemicals."

"EPA's preliminary findings on an air pollution standard with widespread public health implications are being bluntly rejected by most members of a key advisory panel."

"Over the course of three years, NASA flew a plane carrying gas-imaging equipment above California and made a discovery that surprised even the state’s own environmental agencies: A handful of operations are responsible for the vast majority of methane emissions."

"The last time Jeff Holmstead and John Walke sat at the same congressional witness table, they tangled vigorously over an industry-backed proposal to overhaul EPA's New Source Review program."

"Emissions of a banned ozone-destroying gas that had risen unexpectedly since 2012 appear to have declined in the last two years, according to preliminary data reported by scientists on Monday."

"Air pollution in New Delhi and surrounding towns reached the worst levels so far this year on Sunday, with authorities in the world’s most polluted capital city having already declared a public health emergency and ordered the closure of schools."