The ozone at altitude is worse than that in the valleys below. Its a sad fact that many in the mountains refuse to acknowledge. Ozone, nasty stuff, is usually much worse in the San Bernardino Mountains than in the Valley below. The Valley gets the solid ugly stuff and the Mountian communities get the invisible ugly stuff. A quick check of the AQMD site reveals the sad fact that those that think they are getting fresh mountain air can be suffering through much worse than those below.
http://www.aqmd.gov/telemweb/areamap.aspx