That Time The U.S. Government Secretly Sprayed Its Own Citizens With Germs.

This week, I learned that during the early Cold War, the U.S. government secretly tested how biological agents would spread by using American cities and transit systems as live test environments.

My Brief:

• Operation Sea-Spray was a 1950 U.S. Navy secret biological warfare experiment in which Serratia marcescens and Bacillus globigii bacteria were sprayed over the San Francisco Bay Area in California in order to determine how vulnerable a city like San Francisco would be to a bioweapon attack.

• They released bacteria off the coast to form an aerosol cloud and then monitored how it moved through the city.

• Nearly all of San Francisco’s roughly 800,000 residents were likely exposed, and none of them were informed that the test was happening.

• Officially, the operation was described as a way to understand how vulnerable a major U.S. city was to biological attack.

• In 1966, the U.S. Army conducted another secret test in the New York City subway system.

• Operatives dropped light bulbs filled with microorganisms onto the tracks, relying on the air pushed by passing trains to spread the particles through tunnels and station platforms.

• The goal was to see how quickly and widely a biological agent could move through dense, enclosed transit infrastructure under normal operating conditions.

Why I found it interesting :

I found Operation Seaspray particularly fascinating because it reveals a rarely discussed side of government decision-making—one where scientific curiosity and national security priorities outweighed public consent. The idea that the U.S. military deliberately released bacteria over San Francisco in the 1950s, without informing the civilian population, raises serious ethical questions about transparency and accountability. What makes it especially compelling is how it reflects the Cold War mindset, where perceived threats justified unconventional and sometimes morally ambiguous testing methods. It forces you to consider how much trust citizens place in institutions, and whether that trust was, or is, always warranted when the full story remains hidden for decades.

Enter the Rabbit Hole:

• The True Story of the Military's Secret 1950 San Francisco Biological Weapons Test

• Secret Testing in the United States

• Doctors who planned germ warfare tests in the 1950's...

• CIA Document: Army Tested Germs On Public In '64

• In 1950, the U.S. Released a Bioweapon in San Francisco

• The US has a history of testing biological weapons on the public – were infected ticks used too?

Documents:

• U.S. ARMY ACTIVITY IN THE U.S.BIOLOGICAL WARFARE PROGRAMS