Tighter emmisions standards

Well, being born (1955) and raised in California, I don't miss the good ol days of a reddish-brown sky, eyes tearing up when I went outside, painful aching lungs during sports, and not being able to see Catalina Island just 26 miles off the coast nor the Los Angeles Mountains just 30 miles away. Some of my friends who moved here from other states had the same complaints in their home cities. The smog pumps in CA cars beginning in 1966 actually were a blessing that was not really appreciated. The talk around SoCal was that the time table for the clean air standards would not allow the car manufacturers or the petroleum industry to meet those standards. The timing retardation was to address the NOx emissions that produced photo-chemical smog (burning eyes, aching lungs) and acid rain. Today's technology allows us to have greater horsepower and cleaner burning engines that could not be imagined back in the Muscle Car era. It is ironic that, in the beginning, technology was way behind CA law and now CA law is way behind technology. The original catalytic converters were made with Paladium and Silver. It was common to find out your cat was stolen in order to make money off the metal. Since then, zeolites (a form of Aluminum oxide) were developed that performed much better than the Paladium-Silver cats and were/are much cheaper to produce. CA law needs to be ammended to allow engine original equipment to be replaced by modern technology.It is nice to be able to breathe cleaner air, see without tearing, run without aching lungs, and to see Catalina or the mountains every day. All of that and I can buy a 500+ horsepower car that burns cleaner than the legendary elephant 426 street Hemi.

please explain how pumping outside air into the exhaust changes what comes out? yes it says its "cleaner" because it diluted with forced oxygen, but the original combustion gas is still there, in the same amount...