Yup you got it! Here's a little scenerio:
Growing up we had smog indexes and they still do! When I was 23yrs younger out and about playing football or skateboarding I would have to take a break because it felt like I smoked a pack of Reds. Fast forward to this past year in April I went home to visit and normally you wouldn't see Smog until you were past this certain part of the Foothills. Not any more the smog has made it's way past the hills into the High Desert. Another thing I love about here other than fishing, hunting, fresh air is crime! You hardly EVER hear sirens or see police choppers chasing people down the Interstate. I will be one of them transplants that never leave!