The potential exposure of humans and animals on the ground to the high power microwave beams is a significant concern with these systems. At the Earth's surface, a suggested SPSP microwave beam would have a maximum intensity at its center, of 23 mW/cm. While this is less than 1/4 the solar irradiation constant, microwaves penetrate much deeper into tissue than sunlight, and at this level would exceed the current United States Occupational Safety and Health Act (OSHA) workplace exposure limits for microwaves at 10 mW/cm At 23 mW/cm, studies show humans experience significant deficits in spatial learning and memory. If the diameter of the proposed SPSP array is increased by 2.5x, the energy density on the ground increases to 1 W/cm. At this level, the median lethal dose for mice is 30-60 seconds of microwave exposure. While designing an array with 2.5x larger diameter should be avoided, the dual-use military potential of such a system is readily apparent.