Radio frequency (RF) communication safety guidelines protect workers and the general public.
Thermal heating of the human body and radio frequency (RF) shocks and burns, known as electrostimulation, are two health effects caused by exposure to high levels of RF energy. Although this safety hazard mainly concerns workers in the communications industry, the general public can also be affected. For this reason, RF safety guidelines were developed to protect industry workers and the general public.
History
The FCC has adopted RF safety guidelines based on qualified recommendations.
The U.S. Federal Communications Commission is required by the National Environmental Policy Act of 1969 (NEPA) to evaluate how RF energy emitted by transmitters and facilities under its regulatory control impact human health. Guidelines were adopted by the FCC in 1985 and updated in 1996 to establish safe RF exposure and absorption limits based on recommendations from the National Council on Radiation Protection and Measurements (NCRP), the Institute of Electrical and Electronics Engineers (IEEE), and the American National Standards Institute (ANSI).
Types of Radiation
RF radiation is considered non-ionizing.
Radiation is manifested as either ionizing or non-ionizing radiation. Ionizing radiation such as X-rays and gamma rays carry high-intensity electromagnetic energy that can damage biological tissue and genetic DNA material. However, the energy levels associated with RF radiation is not great enough to cause molecular cell damage and falls under the category of non-ionizing radiation.
RF Exposure Safety Guidelines
The maximum permissible exposure (MPE) limit is one RF safety metric.
The FCC's Office of Engineering and Technology (OET) established maximum permissible exposure (MPE) limits based on NCRP recommendations in terms of the strength of the electric and magnetic fields and also power density for transmitters operating at frequencies between 300 kilohertz (kHz) and 100 gigahertz (GHz). The maximum permissible exposure limits were defined for two distinct categories depending on whether the RF radiating source involved a controlled or an uncontrolled environment.
The occupational/controlled maximum permissible exposure limit applies to occupational workers who are fully aware of the potential health risks as a consequence of their employment. The limit also applies to the general public who is cognizant of the risk but can physically limit their exposure time. The general population/uncontrolled maximum permissible exposure limit pertains to both the general public and occupational workers who are not fully aware of the potential health risks.
SAR Safety Guidelines
Specific absorption rate (SAR) is another RF safety metric.
Specific absorption rate is a measure of the rate at which energy is absorbed by biological tissue when exposed to RF radiation, leading to thermal heating effects. Experts generally agree that a specific absorption rate of four watts per kilogram (W/kg) averaged over the entire body mass is conservative and considered safe. Much of this research was based on exercise activities because overexertion closely resembles the effects of high-RF energy exposure. For example, moderate exercise is comparable to a specific absorption rate of 2.0 to 2.5 W/kg.
Cell Phone Compliance
The FCC requires cell phone makers to comply with SAR limits.
The FCC defines portable devices (including cell phones) as those in which the radiating structure (i.e., antenna) is within 20 centimeters of the body during normal usage. The FCC requires mobile phone manufacturers to demonstrate compliance with a specific absorption rate limit of 1.6 W/kg averaged over any one gram of tissue. Specific absorption rate information for a specific cell phone can be obtained from the FCC identification number often printed on the phone's case.
