Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, HETA 2011-0097-3200, 2013 Dec; :1-29
The Health Hazard Evaluation Program received a request from a federal research institution. Health and safety managers were concerned about potential employee exposures to radiofrequency (RF) radiation at the institute's atomic time radio station. The radio station broadcasts time announcements, standard time intervals, standard frequencies, geophysical alerts, marine storm warnings, and global positioning system status reports. The station radiated 5 kilowatts on a 2.5-MHz antenna array and 10 kilowatts on 5-, 10-, and 15-megahertz (MHz) antenna arrays. Each frequency was broadcast from a separate transmitter. Additionally, a weather station was on top of a 45-foot tower. Four employees spent most of their time working in the radio station building. Although employees spent little time in the antenna field, they could be exposed to electric and magnetic fields when cleaning, repairing, and painting antennas; maintaining the weather station; or mowing the antenna field. NIOSH investigators assessed RF exposures by collecting measurements around the antennas as well as areas on the inside, outside, and on the roof of the radio station building in January 2012. Electric and magnetic field strengths were below action levels and exposure limits on the roof, in the office, and in the transmission room of the radio station building as well as in the cab of the pickup while mowing the antenna field near transmitting antennas. Electric and magnetic field strength measurements exceeded action levels and exposure limits in certain areas of the antenna field. Electric and magnetic field strengths measured near the 5-, 10-, and 15-MHz antennas exceeded exposure limits and magnetic field strengths exceeded exposure limits about halfway up the weather station tower and near unpowered 10- and 15-megahertz antennas. During activities involving primary or backup antennas that were powered off, or when servicing the weather station, employees could be overexposed to magnetic fields induced from nearby transmitting antennas. NIOSH investigators recommended the research institution (1) start a comprehensive RF safety program and assign a safety officer to develop and oversee the program, (2) install caution signs to identify areas where exposure limits could be exceeded, (3) reduce power to a primary antenna before working on the standby antenna of the same frequency or vice versa, (4) reduce power to the 5-megahertz antenna before servicing the weather station, and (5) train employees on the potential hazards associated with RF exposure.
Region-9; Health-hazards; Radiofrequency-radiation; Exposure-assessment; Radio-waves; Communication-systems; Communication-workers; Magnetic-fields; Warning-systems; Signal-devices; Signaling-systems; Radiation; Radiation-exposure; Radiation-measurement; Nonionizing-radiation; Electrical-fields; Electrical-measurement; Electrical-transmission;
Author Keywords: Research and Development in the Physical, Engineering, and Life Sciences (except Biotechnology); radiofrequency; RF; radio station; non-ionizing radiation; electric field; magnetic field