USC is in downtown LA area, not the valley where Claremont is located.
But the whole LA basin and adjacent valley areas are immeasurably better smog-wise than they were 30-40 years ago. Calif has had the strictest air pollution standards for cars for years and it has made all the difference in the world.
We were just in Pasadena 2 weeks ago and while it was hot, it was NOT smoggy at all.