Radiofrequency Safety Standard-Setting in the United States

Abstract

The development of standards and recommendations to prevent harm from exposure to radiofrequency (RF)/microwave energy has been an on-going activity in the United States since the early 1950’s. Before 1958, exposure limits ranging from 0.1 to 100 mW/cm² (1 to 1000 W/cm²) were used at one time or another by different organizations. The lower values were usually specified as levels that were safe for indefinite exposure; the higher values as limits that should not be exceeded. The rationale was to limit any concomitant temperature rise to less than approximately 1 °C; the justification was the lack of demonstrated harm to humans even at the higher level. Even though most organizations in the US adopted 10 mW/cm² (100 W/m²) in 1958, questions about the validity of this value led to the formation of a committee charged with developing standards, through an open consensus process, that would address the RF/microwave safety issue. The resulting committee, now known as the Institute of Electrical and Electronics Engineers Standards Coordinating Committee 28 has been by far the most innovative and influential on the subject and the remainder of this paper will address activities of this committee and its latest standard IEEE C95.I-1991.