Trinity (nuclear test)
A tower-like structure was used for the experiment. This favored radioactive fallout. The landscape and the winds meant that "radioactive hot spots" formed. For four to five days after the experiment, farmers observed a flour-like white fallout. People about  around the site used rainwater for drinking. The people in the area were not warned, or informed about ways to protect themselves.  There were no evacuations. Instruments that were not adapted to do these measurements registered explosion rates up to 1.4 µC/kg/s. It was nearly impossible to assess the risk of contamination through α-radiation that came from about  of unexploded Plutonium.