I'm surprised no one has mentioned Operation Sea-Spray:
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 may be to a bioweapon attack
People got sick and one person died, all from bacteria they thought to be harmless at the time.
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 may be to a bioweapon attack
People got sick and one person died, all from bacteria they thought to be harmless at the time.
https://en.wikipedia.org/wiki/Operation_Sea-Spray