GRANTS PASS, Ore. (AP) — A new study finds that while U.S. controls on air pollution have been driving down a major ingredient of smog, ozone blowing over from Asia is raising background levels over California and other western states.
Dan Jaffe is a professor of atmospheric chemistry at the University of Washington-Bothell who contributed data to the study. He says it is the first time Asian pollution has been directly linked to ozone over the United States.
Lead author Owen Cooper, a research scientist at the University of Colorado, says the amounts are small, and have been traced only at middle altitudes.
But he says the amounts have been steadily rising since 1995, and probably longer, and could complicate U.S. efforts to lower ozone levels at home.
