Sure, it isn't the Canadian Rockies, but it is nothing like a bad day in San Bernadino or Bakersfield. Check out the summer AQI maps for different parts of the country at http://www.airnow.gov/ (site is down right now).

I remember visiting LA from MI when I was a kid in the 80s and "tasting" smog in the air for the first time. Admittedly LA has gotten a bit better since then.