BACKGROUND

Life exists in the presence of electromagnetic radiation, natural or man-made. The sun is a major source of natural ionizing and non-ionizing electromagnetic radiation. Although the earth’s atmosphere shields people from most ionizing radiation (e.g., x-rays and gamma rays), we are routinely exposed to non-ionizing electromagnetic radiation. Natural non-ionizing electromagnetic radiation can be categorized into ultraviolet, visible light, infrared, and radio frequency radiation.

Technological advancement has resulted in increasing amounts of non-ionizing radio frequency electromagnetic radiation from man-made sources (e.g., high-voltage power lines, TV and radio broadcasts, mobile phones, microwaves, or satellite signals).4 Military service members may encounter additional duty-related RF-EMF devices.

In response, the Department of Defense (DoD) and the North Atlantic Treaty Organization have been evaluating potential health and safety impact of human exposure to emissions of RF-EMF systems that we develop or use.5 DoD Instruction 6055.11, Protecting personnel from electromagnetic fields, May 12, 2021 also established guidelines and policies for protecting personnel in military environments from overexposure to electromagnetic fields between the 0 hertz (Hz) and 300 GHz frequency spectrum and directs DoD components to follow the Institute of Electrical and Electronics Engineers (IEEE) Standard C95.1-2345 for ERL limits (Appendix A).3,6

The IEEE established two military exposure environments (i.e. restricted and unrestricted) that can be further divided into three zones. Zone 0 applies to unrestricted environments and Zone 1 and Zone 2 apply to restricted environments.3 Appendix A shows IEEE safety exposure limits for Zone 0 and Zone 1.3 Aboard Navy ships, for example, high-power RF-EMF emitters (e.g., antennas below 100 MHz) can induce current through human body when in close proximity.7 The US Navy defined almost all topside of a ship as restricted “controlled” areas whereas RF-EMF radiation risk mitigation, protection, and management are essential for military operations.

Examples of military RF-EMF emitting sources are listed below based on application categories:8

- COMMUNICATIONS: Military Auxiliary Radio System, Combat-net radio, Land Mobile radio, airborne and ground DataLink or terminal, satellite communication terminal, tropospheric scatter system, wireless local area network, or AM and FM broadcast station.
- NAVIGATION: fixed navigation systems such as VHF Omni-Directional radio, Tactical Air Traffic Navigation, or Instrument Landing System; airborne systems such as radar altimeter, doppler radar, or terrain-following radar.
- RADAR: air defense ground-based radar, airport surveillance radar, counter-battery radar, synthetic aperture radar, moving target indicator, height-finding radar, fire control radar, side looking radar, weather radar, or mapping radar.
- ELECTROMAGNETIC COUNTERMEASURES: electronic countermeasures, threat recognition system, counter-Improvised Explosive Device equipment, or radio and radar jammers.
- INDUSTRY/COMMERCIAL: RF welders or heat sealers, RF induction heating, plasma processing, or microwave heaters.
- MEDICAL: MRI, RF diathermy, patient monitors, cauterization electrosurgery, and interstitial microwave hyperthermia.
- DIRECTED ENERGY WEAPONS: the Active Denial System, Vigilant Eagle, the Tactical High-power Operational Responder, and the Counter-electronics High-power microwave Advanced Missile Project.

Historically, RF-EMF overexposures were less common in military environments and most reported cases were below exposure limits (see Clinical Scenarios below).9,10 Over the nine-year period from 2014 to 2022, the U.S. Air Force reported and investigated 126 suspected cases among 38,000 personnel who routinely worked closely with high-power RF-EMF emitters.10 Only one patient had EMF-related injury confirmed by these investigations.10

CLINICAL SCENARIOS

CASE 1. A worker and supervisor were overexposed to electromagnetic countermeasures (ECM) pod radiation at an electronic warfare maintenance facility. The worker turned on an ECM pod without its required Radiofrequency Termination Hat (RTH). The supervisor noticed the problem upon entering the room and immediately placed the RTH on the ECM. The supervisor had approximately 30 seconds overexposure that resulted in 1st degree burns (i.e., skin reddening) to the left ear and face. The worker reported feeling nausea with no thermal injury. Investigator determined that the applicable ERL was exceeded by more than a factor of 10 based on physical signs and symptoms of the two individuals.

CASE 2. A service member was performing routine maintenance on a Patriot ground-based radar during a field training exercise. The service member worked directly in front of the radar for 10-15 minutes before learning that the radar was on and active. The service member moved away from the radar and reported profuse sweating, metallic taste, nausea, vomiting, headache, and blurred vision. Symptoms resolved and the Soldier was discharged the next day. Investigator calculated the exposure exceeded the ERL by a factor of 10.

CASE 3. A worker walked past a cordon, which was located 120 ft and 60 degrees away from the cone of a running F-16 radar (i.e. AN/APG68). Then, the worker walked toward the F-16 radar at ~100 ft from the cone before turning back out of the cordon. The exposure duration was 3-5 seconds. Calculated power density was 9.44 W/m2 at 100 ft, which was below the ERL. The worker reported feeling warm and headache. Symptoms resolved with no further effects.