Associated Press: Ozone blowing over from Asia is raising background levels of a major ingredient of smog in the skies over California, Oregon, Washington and other Western states, according to a new study appearing in Thursday’s edition of the journal Nature. The amounts are small and, so far, only found in a region of the atmosphere known as the free troposphere, at an altitude of two to five miles, but the development could complicate U.S. efforts to control air pollution. Though the levels …