President Donald Trump has revoked a scientific ruling critical to federal action to combat greenhouse gases.
The finding from 2009 ruled that a range of greenhouse gases were a threat to public health, a conclusion which has underpinned federal efforts to reduce emissions, particularly in vehicles.
But in what the White House is called the "largest deregulation in American history", Trump has now reversed that ruling, insisting cars will become cheaper as a result and that manufacturing costs will drop $2,400 per vehicle.
The BBC reports the move has been criticised by environmental groups that plan to lodge a legal challenge against it.
Speaking to the media, Trump branded the 2009 ruling "a disastrous Obama-era policy that severely damaged the American auto industry and massively drove up prices for American consumers".
He added: "This radical rule became the legal foundation for the Green New Scam, one of the greatest scams in history."
Reacting on social media, former president Barack Obama said: "Without it, we'll be less safe, less healthy and less able to fight climate change — all so the fossil fuel industry can make even more money."