Cellular phones and bluetooth devices have become essential electronic devices for many people in today's society. However, these devices emit low radio frequencies that may be harmful to both the skin and brain tissue. The thermal wave model is used to predict an unsteady temperature distribution of microwaves as it transmits through the human head. A time dependent finite difference method models a multilayer system depicting this external heat source passing through three mediums: skin, bone, and brain. This model accounts for the heat generated within the body from the chemical reactions of the tissue and a relaxation time in order to account for the response time the tissue takes caused by the perturbation. Previous human head studies took these values to be negligible. Parameters of the head for both the adult and child are shown. Various parameters, including frequency, power density, and relaxation time were varied. It was shown that the relaxation parameters was important; however, changing other variables such as frequency and power density within a certain range are ineffective. This manuscript is aimed to identify the potential threats on the human body caused by the everyday use of today's technologies such as cellular phones and bluetooth devices. (C) 2013 Elsevier Ltd. All rights reserved.