It happens because of LA geography which allows smog to become trapped. https://www.latimes.com/california/story/2021-11-11/how-an-inversion-over-la-basin-acts

It happens because of LA geography which allows smog to become trapped. https://www.latimes.com/california/story/2021-11-11/how-an-inversion-over-la-basin-acts-like-a-lid-on-a-pot https://www.latimes.com/california/story/2021-11-11/how-an-i...