Asian Pollution Smogging American Spring

Smoke rising from sticks above inversion

"In springtime, pollution from across the hemisphere, not nearby sources, contributes to the ozone increases above western North America." — Owen R. Cooper

Pollution blown across the entire North Pacific from the smokestacks of Asia’s industrial belt is responsible for worsening air quality in the western United States, researchers say.

Writing in the journal Nature, lead author Owen Cooper of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado at Boulder says the foreign pollution could unfairly hamper local efforts to meet Clean Air Act standards for ozone pollution at ground level.

He says research reveals that springtime ozone levels 2 to 5 miles above the surface have risen by 29 percent as Asia’s heavy industry has expanded sharply between 1984 and 2008.

Such a surge could only be accounted for by pollutants from Asia that are converted to ozone and carried to North America by strong and prevailing westerly winds, Cooper concludes.

No evidence was found that the pollution could have come from local emissions in North America, the report says.

The slice of the atmosphere studied is far below the protective stratospheric ozone layer but above ozone-related, ground-level smog that is harmful to human health and crops.

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