Atomic Energy Commission Map
This is a 1953 Atomic Energy Commission Map that shows fallout exposure levels for areas around the Nevada Test Site after the Upshot-Knothole series that ran between March and June of 1953. Colors represent roentegen exposure levels (measured in per hour exposure) for the year 1953:
Black: 100+ R
Red: 50-99 R
Green: 10-49 R
Blue: 5-9 R
Yellow: 1-4 R
Normal background radiation in the environment is somewhere around 200 milliroentgens per year and that 500 roentegen (per hour) is a lethal dose to humans.
This map is held by the Utah State Archives and Records Service and can be found in series 11571.