It has to do with LA geography. The surrounding landscape traps the pollution so it cannot dissipate away from the city.

Different geography/topology. https://www.clarity.io/blog/a-closer-look-at-los-angeles-inf...

I'm certain the number of children suffering illness or even dying due to air pollution from Texas refineries is more than zero. Not very high, I imagine, but not zero. There is a very real human cost to these things which we really like to ignore.