“One would say the health benefit outweighs the cost to the industry. There are existing high levels of emissions for diesel fleets," said Margo Oge, who directs the U.S. EPA’s Office of Transportation and Air Quality, at the North American Motor Vehicle Emissions Control Conference. "Experts will tell you we can't have a sustainable environment if we don't take action," she said.
Truck engine manufacturers fought the regulations, saying they could not meet new standards because the technology was lacking. Courts have rejected these arguments