Prof. Hans Thirring of Vienna proposes drying a solution of the RW [radiological warfare] agent upon sand, or metal powder. Naming the preparation "death sand," he calls it "the lightest and most transportable of all weapons of mass destruction."
Airplanes for "death-sand" attacks could resemble those used for crop dusting and spreading fertilizer from the air. A British plane for the latter purpose has dropped five tons of chemicals in a single experimental flight.
To protect occupants from the cargo's radioactivity a death-sand plane would need heavy shielding. (After calculating its weight, one scientist suggested dropping the shielding instead of the RW agent on the enemy!) But shielding could be omitted if crewless planes, under radio control from accompanying aircraft, laid the sand.
Troops in an area sprinkles with death sand will have no choice but to get out. Those who remain will receive a fatal dose in anywhere from a few hours to several weeks, depending on the intensity of the radioactivity. Like victims of A-bomb radiation, they will suffer nausea, loss of hair, anemia, and hemorrhages. But those who flee at once will suffer no ill effects.
I've visited the Hoover Dam a number of times but had never heard about its unusual acoustic properties that produce "a soothing effect on violently ill mental patients when they listen to musical recordings made at the dam site."
I searched in vain for copies of these Hoover Dam sound recordings.