Operation Sea-Spray

https://pennybutler.com/clouds-of-secrecy-usa/
On September 20, 1950, a US Navy ship just off the coast of San Francisco used a giant hose to spray a cloud of microbes into the air and into the city’s famous fog. The military was testing how a biological weapon attack would affect the 800,000 residents of the city.
(Operation Sea-Spray)
https://en.wikipedia.org/wiki/Operation_Sea-Spray