A series of calculational models (including multi-region FDTD in which two FDTD domains, representing the antenna and the exposed subject, are linked using Kirchoff's integral) was used to determine the distances from cell phone towers that current human exposure limits (SAR) would be exceeded. For the 900 MHz (GSM), the computed compliance distances were 50 cm for whole body SAR of 0.08 W/kg; 230 cm for local SAR of 1.6 W/kg averaged over 1 g of tissue; and 110 cm for local SAR of 2.0 W/kg averaged over 10 g of tissue. For the UMTS model, the computed compliance distances were 60 cm for whole body SAR of 0.08 W/kg; 350 cm for local SAR of 1.6 W/kg averaged over 1 g of tissue; 100 cm for local SAR of 2.0 W/kg averaged over 10 g of tissue. At 2-meters, the GSM model produced values for whole body, local (1 gram), and local (10 grams) of 1.06 mW/kg, 0.036 W/kg, and 0.023 W/kg, while the UMTS values were 0.95 mW/kg, 0.125 W/kg, and 0.065 W/kg. The authors concluded that the most stringent limit to compliance comes from local SAR restrictions, rather than whole body, and that this investigation found differences of up to threefold between ICNIRP and IEEE limits.