We have gotten rid of the deadliest byproducts. https://www.statista.com/statistics/501284/volume-of-nitroge... Rate of NOx have plummeted since the 1979 Nitrogen Oxide Protocol. If we focus on byproducts which cause Acid Rain and not just generic 'carbon', a lot of progress has been made since Nixon founded the EPA in 1970, mostly in the early years