IRVINE (AP) — James Pitts, a pioneering smog researcher whose work spurred California’s groundbreaking clean-air regulations, has died. He was 93.

His wife, UC Irvine professor Barbara Finlayson-Pitts, tells the university that Pitts died in his sleep Thursday at their Irvine home.

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Pitts began researching air pollution in the 1950s at the University of California, Riverside. At the time, the causes and dangers of smog weren’t well-understood.

Pitts helped create the Statewide Air Pollution Research Center and directed it for 18 years. His team built the first smog chamber to study photochemical smog.

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It was visited by scientists and politicians from around the world.

Pitts joined his wife at UC Irvine in 1994.

Pitts co-authored nearly 400 scientific books and publications. He also served on panels at the California Air Resources Board.

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