Why is there so much smog in L.A?

I think this article explained it good- http://www.quora.com/Why-is-there-so-much-smog-and-air-pollution-in-L-A

I'm planning on going to California sometime by the beginning of next year for vacation. I heard that you can literally taste L.A air, is this true? Any places you'd recommend or things to look out for? I know I probably should've posted this in travel, but whatever.