Infrared thermal imaging to measure local temperature rises caused by handheld mobile phones

This paper investigates local heating effects of the ear-skull region that handheld mobile phones can cause in humans. The goal is to visualize, quantify, and compare these thermal effects in various subjects using different commercial mobile phones in the normal contact position during standardized conversations. Thermal imaging is capable of measuring local temperatures directly, as opposed to other methods, which can only derive temperatures if the electromagnetic near-field pattern of the phone, the energy-absorbing tissue properties, and the blood-flow situation are exactly known. The strength of local temperature rises is an indicator of the total exposure related to radiofrequency electromagnetic radiation from the mobile phone. It is shown in this paper that different commercially available handheld mobile phones can cause very different thermal effects under identical experimental conditions. The measurement results are expected to help consumers in choosing those phones that cause the least thermal influences and biological effects. They might also help change the phone user´s behavior in order to minimize the exposure to electromagnetic radiation.