Dorset Biological Warfare Experiments
The Dorset Biological Warfare Experiments were a series of experiments conducted between 1953 and 1975 to determine the extent to which a single ship or aircraft could dispense biological warfare agents over the United Kingdom. The tests were conducted by scientists from Porton Down, initially using zinc cadmium sulfide (ZnCdS) as a simulated agent.
Source: Wikipedia — Dorset Biological Warfare Experiments (CC BY-SA 4.0)