Smog in a Rural Valley? Mystery Is Solved

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Une vache en Californie © Justin Sullivan/Getty Images/AFP

The smog in California’s San Joaquin Valley has puzzled scientists for years. Even though the region is largely rural and agricultural, its smog levels exceed those of densely populated cities like Los Angeles.

Some have speculated that animal waste or pesticides are the cause: both emit ozone, a primary ingredient in smog. But a recent study published in the journal Environmental Science and Technology suggests that the primary culprit is actually cattle feed.

New York Times

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