Back in late 1949, people throughout Los Angeles County reported a strong odor that smelled like garlic. The smell persisted for weeks, periodically increasing in intensity. Some residents took to wearing gas masks. There were reports of the fumes being so strong that they discolored fences and buildings. There was a widespred fear that it was a poison gas attack.
Despite a lot of speculation, I'm not sure that the source of the mystery odor was ever identified, although leading theories were that it was either coming from the Los Angeles River bed, or from a chemical factory. It became known as the invasion of the Garlic Fog. [Sydney Morning Herald, Aug 7, 1949
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