TABLE 1 ROUGH ESTIMATE OF REDUCTION IN GAMMA RADIATION WITHIN STRUCTURES PERCENTAGE OF GUT-OF-DOORS LEVEL TYPE STRUCTURE ONE STORY FRAME HOUSE First Floor 50 Basement (Center) 10 Basement (Side) Zz 10 MULTI STORY REINFORCED CONCRETE 10 Lower Floors (Away from windows) ~ 0.1 Basement SHELTER (equivalent to three ~ 0.1 feet of earth) - 37 - 4