Most of that stuff isn't true smog, like it was during the days of indians and early settlers. The brownish haze is mostly unburned HC's and NOx, aka photochemical smog.
Los Angeles has a tough time because of an "inversion layer." In most areas, the sun heats up the ground and causes air to be warmed. This warm air and everything within it (smoke, debris, pollution) gets pulled up by convection as air rises to the cold atmosphere. I forget exactly why, but I believe it is due to the Santa Ana winds, that hot dry air is blown above Los Angeles from the deserts north and east of the basin. Essentially, air near the ground is around the same temperature or cooler than air up above so it just sits. During the winters, when NO2 goes to NO (if I remember correctly), the skies really clear up and the area gets really beautiful...especially with the San Gabriels in snowpack.
Just biking along the beach the other day I noticed an extremely thick, brown haze over the ocean...so bad that if a glass of water had the same color you'd only drink it by force. The Port of LA is a major polluter, along with anchored container ships just idling in the harbor. Looking the left (south torward Orange County) the skies were clear...panning to the right (north torward Los Angeles) the skies grew to an opaque brown. I hear they are trying to electrify the Port of LA, though...
Now if only they'd think about electrifying
LA...
- LostCause