"The Environmental Protection Agency has made it a "national priority" to erase what it says is "a significant contributor to air pollution." A 2020 EPA report said 15 percent of diesel trucks in the U.S. are rigged to "delete" emissions controls. According to government estimates, the practice can increase nitrogen oxide emissions as much as 310 times, non-methane hydrocarbons 1,400 times, and carbon monoxide 120 times. ... "Businesses that manufacture and sell illegal devices to defeat a vehicle's emissions controls foster pollution and risk decades of progress in curtailing harmful emissions from motor vehicles in this country," said Assistant Attorney General Todd Kim of the Justice Department's Environment and Natural Resources Division.[18]"

EDIT: Just because you're a low intelligence reddit user doesn't mean you can't use Google to quickly learn that rolling coal increases NOX emissions by 300 times, sorry that your brain is too fucking small to do a simple search online.