Caltech Solves for: Smog

For decades, politicians in Southern California vowed to clean up the foul-smelling health hazard of smog. They were powerless to act, however, because no one knew how smog formed. A partnership between two scientists—one a Caltech biochemist, the other a prominent Caltech alum and benefactor—revealed the secret of smog, and led to bluer skies and cleaner air.

Back in the ’40s, as eyes stung and lungs burned, chemist and inventor Arnold O. Beckman (PhD ’28) decided that he wanted to help solve the problem.

A common cry among policymakers was, “There’s no time for research.” Beckman, like all of the Caltech greats, knew better. Having maintained a connection to the chemistry faculty at his alma mater, he had the perfect recruit in mind: microchemist Arie Haagen-Smit, who was studying the chemistry underlying the scent and flavor of pineapple.

In 1948, Beckman asked Haagen-Smit the favor of analyzing a sample of fetid brown sludge concentrated from the air. Haagen-Smit complied, and his results pinpointed hydrocarbons as a key ingredient. His findings were immediately controversial.

Initially averse to the political gales swirling around the issue, Haagen-Smit would have preferred to return to his own research. But Beckman had a plan to retain this ally in the battle against smog. He arranged for a researcher with a contrary point of view to give a talk at Caltech—and he made sure that Haagen-Smit attended, seated right there by his side.

When the visitor spoke about Haagen-Smit’s research, bemoaning that such a good scientist could be so sorely misled, Haagen-Smit saw red. He knew he was right, and he was going to prove it. That moment of pique pushed him to continue his work on smog.

Caltech extended Haagen-Smit the freedom to work for a year in a lab provided by Beckman and L.A.’s Air Pollution Control District—and in that time, Haagen-Smit was able to identify two emissions catalyzed by sunlight as the culprit of smog.

By 1968, Haagen-Smith was appointed to the state’s Air Resources Board and continued working with Beckman and a coalition of others to make automobile emissions safer for people. Their efforts led to policy changes that eventually brought astonishing improvements to air quality now taken for granted.

To read more about this powerful partnership, see the Caltech Archives’ oral histories with Arnold Beckman and with Arie Haagen-Smit’s wife, Zus Haagen-Smit.