It all began in late September of 1950, when over a few days, a Navy vessel used giant hoses to spray a fog of two kinds of bacteria, Serratia marcescens and Bacillus globigii — both believed at the time to be harmless — out into the fog, where they disappeared and spread over the city.

The unsuspecting residents of San Francisco certainly could not consent to the military’s germ warfare test, and there’s good evidence that it could have caused the death of at least one resident of the city, Edward Nevin, and hospitalized 10 others.

Over the next 20 years, the military would conduct 239 “germ warfare” tests over populated areas, according to news reports from the 1970s.

These tests included the large-scale releases of bacteria in the New York City subway system, on the Pennsylvania Turnpike, and in National Airport just outside Washington, D.C.

– From the MSN article: ‘One of the Largest Human Experiments in History’ was Conducted on the Unsuspecting Residents of San Francisco