When Biological Weapons Were Secretly Tested in San Francisco

Bay Curious

KQED

History, Society & Culture, Places & Travel

4.9 • 999 Ratings

🗓️ 6 November 2025

⏱️ 18 minutes

🔗️ Recording | iTunes | RSS

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Summary

In 1950, the U.S. military sprayed bacteria over San Francisco as part of a biological weapons test. The test team thought the bacteria it used was harmless, but several people got sick and one person died. We explore the history and impacts of this clandestine operation, now known as Operation Seaspray, on U.S. military policy and one man's family. Additional Resources: The True Story of the Military's Secret 1950 San Francisco Biological Weapons Test Read the transcript for this episode Sign up for our newsletter Enter our Sierra Nevada Brewing Company monthly trivia contest Got a question you want answered? Ask! Your support makes KQED podcasts possible. You can show your love by going to https://kqed.org/donate/podcasts This story was reported by Katherine Monahan. Bay Curious is made by Katrina Schwartz, Gabriela Glueck and Christopher Beale. Additional support from Olivia Allen-Price, Jen Chien, Katie Sprenger, Maha Sanad, Alana Walker, Holly Kernan and everyone on Team KQED.

Transcript

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0:00.0	This week on KQED's The Bay, a first-hand view of how the government shutdown is affecting Yosemite National Park.
0:09.9	A lot of questions of what is open, what is accessible that we can do right now in the park.
0:14.8	There's been all kinds of stories coming out of Yosemite, stories of unruly visitor behavior, crazy crowds.
0:22.4	Our experience here has really been quite pleasant.
0:25.6	Find this episode of The Bay and more wherever you get your podcasts.
0:31.9	From KQED.
0:34.3	It's a foggy September day in 1950s San Francisco.
0:39.9	For most Bay Area residents, it's a normal day.
0:43.0	People get up and head out to work or school, just like any other day.
0:47.5	The San Francisco Examiner is full of news about the Korean War
0:51.0	and a reminder that daylight savings ends soon.
0:56.0	On the ocean, just outside the Golden Gate, floats a navy boat.
1:00.0	On deck, men hold up what look like big metal hoses and point them at San Francisco.
1:06.0	There's a long low cloud over them that could be mistaken for part of the area's usual fog.
1:13.7	But it's not.
1:16.9	Two days later, Stanford Hospital, which was located in San Francisco at the time, started
1:21.9	seeing something odd.
1:24.9	Doctors started seeing some patients complaining of serious chest pain, shortness of breath, chills, and fever,
1:30.3	symptoms of what's called serratia marcessant's infection.
1:34.3	Doctors had never seen this bacteria at the hospital before, and certainly not in so many patients at one time.
1:42.3	Eleven people got sick, and one would die.
1:47.7	Is it possible that the U.S. military was testing biological weapons on its own citizens?
	...

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