As one of the few native Californians I can attest to the success of our AQMDs. (Air Quality Management Districts)
In high school I often played summer league ball with a sign up in the gym saying "Play at your own risk, Stage 2 alert" (or even stage 3).
I can remember going the entire summer without seeing the mountains (11,000ft peaks 40 miles away).
I can remember my eyes burning in the summers, and getting that "emphyzema feeling" after swimming.
It ain't nirvana yet, but it is much much better now.
I hope we never back down. With the huge market for automobiles in California, the auto makers will have to buckle down. 35 million people can buy a lot of cars.