RF Safety is a growing concern in the Wireless / Electronics Industry.
This page is intended to give you some of the background information on RF Safety.
Please explore the links below to gain a more complete understanding of this
important topic!
IEEE Standard for Safety Levels with Respect to Human Exposure
to Radio Frequency Electromagnetic Fields, 3 KHz to 300 GHz,
IEEE Standard C95.1-1991, Institute of Electrical and Electronics
Engineers, New York, 1992.
For an unbiased assessment of ELF hazards, read the series in
Science, Vol 249 beginning 9/7/90 (p 1096), continuing
9/21/90 (p 1378), and ending 10/5/90 (p 23). Also see Science,
Vol 258, p 1724 (1992). You can find Science in any large
library.
An excellent and timely document is available on the Internet
by an anonymous FTP from: rtfm.mit.edu, /pub/usenet-by-group/news.answers/powerlines-cancer-faq/part1
and part2.
The Environmental Protection Agency publishes a free consumer-level
booklet entitled, "EMF in Your Environment," document
402-R-92-008, dated December 1992. Look for the nearest office
of the EPA in your phone book.
W. R. Adey, "Tissue Interactions with Nonionizing Electromagnetic
Fields," Physiology Review, 1981; 61:435-514.
W. R. Adey, "Cell Membranes: The Electromagnetic Environment
and Cancer Promotion," Neurochemical Research, 1988;
13:671-677.
W. R. Adey, "Electromagnetic Fields, Cell Membrane Amplification,
and Cancer Promotion," in B. W. Wilson, R. G. Stevens, and
L. E. Anderson, Extremely Low Frequency Electromagnetic Fields:
The Question of Cancer (Columbus, OH: Batelle Press, 1989),
pp 211-249.
W. R. Adey, "Electromagnetic Fields and the Essence of Living
Systems," Plenary Lecture, 23rd General Assembly, International
Union of Radio Sciences (URSI), Prague, 1990; in J. Bach Andersen,
Ed., Modern Radio Science (Oxford: Oxford Univ Press),
pp 1-36.
Q. Balzano, O. Garay and K. Siwiak, "The Near Field of Dipole
Antennas, Part I: Theory," IEEE Transactions on Vehicular
Technology (VT) 30, p 161, Nov 1981. Also "Part II; Experimental
Results," same issue, p 175.
R. F. Cleveland and T. W. Athey, "Specific Absorption Rate
(SAR) in Models of the Human Head Exposed to Hand-Held UHF Portable
Radios," Bioelectromagnetics, 1989; 10:173-186.
R. F. Cleveland, E. D. Mantiply and T. L. West, "Measurements
of Environmental Electromagnetic Fields Created by Amateur Radio
Stations," presented at the 13th annual meeting of the Bioelectromagnetics
Society, Salt Lake City, Utah, Jun 1991.
R. L. Davis and S. Milham, "Altered Immune Status in Aluminum
Reduction Plant Workers," American J Industrial Medicine,
1990; 131:763-769.
F. C. Garland, et al, "Incidence of Leukemia in Occupations
with Potential Electromagnetic Field Exposure in United States
Navy Personnel," American J Epidemiology, 1990; 132:293-303.
A. W. Guy and C. K. Chou, "Thermograph Determination of SAR
in Human Models Exposed to UHF Mobile Antenna Fields," Paper
F-6, Third Annual Conference, Bioelectromagnetics Society, Washington,
DC, Aug 9-12, 1981.
C. C. Johnson and M. R. Spitz, "Childhood Nervous System
Tumours: An Assessment of Risk Associated with Paternal Occupations
Involving Use, Repair or Manufacture of Electrical and Electronic
Equipment," International J Epidemiology, 1989; 18:756-762.
D. L. Lambdin, "An Investigation of Energy Densities in the
Vicinity of Vehicles with Mobile Communications Equipment and
Near a Hand-Held Walkie Talkie," EPA Report ORP/EAD 79-2,
Mar, 1979.
D. B. Lyle, P. Schechter, W. R. Adey and R. L. Lundak, "Suppression
of T-Lymphocyte Cytotoxicity Following Exposure to Sinusoidally
Amplitude Modulated Fields," Bioelectromagnetics, 1983;
4:281 -292.
G. M. Matanoski et al, "Cancer Incidence in New York Telephone
Workers," Proc Annual Review, Research on Biological Effects
of 50/60 Hz Fields, U.S.Dept of Energy, Office of
Energy Storage and Distribution, Portland, OR, 1989.
D. I. McRee, A Technical Review of the Biological Effects of
Non-lonizing Radiation, Office of Science and Technology Policy,
Washington, DC, 1978.
G. E. Myers, "ELF Hazard Facts" Amateur Radio News
ServiceBulletin, Alliance, OH, Apr 1994.
S. Milham, "Mortality from Leukemia in Workers Exposed to
Electromagnetic Fields," New England J Medicine, 1982;
307:249.
S. Milham, "Increased Mortality in Amateur Radio Operators
due to Lymphatic and Hematopoietic Malignancies," American
J Epidemiology, 1988; 127:50-54.
W. W. Mumford, "Heat Stress Due to RF Radiation," Proc
IEEE, 57, 1969, pp 171-178.
W. Overbeck, "Electromagnetic Fields and Your Health,"
QST, Apr 1994, pp 56-59.
S. Preston-Martin et al, "Risk Factors for Gliomas and Meningiomas
in Males in Los Angeles County," Cancer Research, 1989;
49:6137-6143.
D. A. Savitz et al, "Case-Control Study of Childhood Cancer
and Exposure to 60-Hz Magnetic Fields," American J Epidemiology,
1988; 128:21-38.
D. A. Savitz et al, "Magnetic Field Exposure from Electric
Appliances and Childhood Cancer," American J Epidemiology,
1990; 131:763-773.
I. Shulman, "Is Amateur Radio Hazardous to Our Health?"
QST, Oct 1989, pp 31-34.
R. J. Spiegel, "The Thermal Response of a Human in the Near-Zone
of a Resonant Thin-Wire Antenna," IEEE Transactions on
Microwave Theory and Technology (MTT) 30(2), pp 177-185, Feb
1982.
B. Springfield and R. Ely, "The Tower Shield," QST,
Sep 1976, p 26.
T. L. Thomas et al, "Brain Tumor Mortality Risk among Men
with Electrical and Electronic Jobs: A Case-Controlled Study,"
J National Cancer Inst, 1987; 79:223-237.
N. Wertheimer and E. Leeper, "Electrical Wiring Configurations
and Childhood Cancer," American J Epidemiology, 1979;
109:273-284.
N. Wertheimer and E. Leeper, "Adult Cancer Related to Electrical
Wires Near the Home," Internat'l J Epidemiology, 1982;
11:345-355.
"Safety Levels with Respect to Human Exposure to Radio Frequency
Electromagnetic Fields (300 kHz to 100 Ghz)," ANSI C95.1-1991
(New York: IEEE-American National Standards Institute).
"Biological Effects and Exposure Criteria for Radiofrequency
Electromagnetic fields," NCRP Report No. 86 (Bethesda, MD:
National Council on Radiation Protection and Measurements, 1986).
US Congress, Office of Technology Assessment, "Biological
Effects of Power Frequency Electric and Magnetic Fields-Background
Paper," OTA-BP-E53 (Washington, DC: US Government Printing
Office), 1989.
Table 9.1--Typical 60-Hz Magnetic Fields Near Amateur Radio
Equipment & AC-Powered Appliances
Values are in milligauss.
ItemFieldDistance
Electric blanket 30-90 Surface
Microwave oven 10-100 Surface
1-10 12"
IBM personal 5-10 Atop monitor
computer
0-1 15" from
screen
Electric drill 500-2000 At handle
Hair dryer 200-2000 At handle
HF transceiver 10-100 Atop cabinet
1-5 15" from
front
1-kW RF amplifier 80-1000 Atop cabinet
1-25 15" from
front
(Source: measurements made by members of the ARRL RF Safety Committee)
Table 9.2--Typical RF Field Strengths Near Amateur Radio Antennas
A sampling of values as measured by the Federal Communications
Commission and Environmental Protection Agency, 1990
Antenna TypeFreqPowerELocationField(MHz)(W)(V/m)
Dipole in attic 14.15 100 7-100 In home
Discone in attic 146.5 250 10-27 In home
Half sloper 21.5 1000 50 1 m from base
Dipole at 7-13 ft 7.14 120 8-150 1-2 m from
earth
Vertical 3.8 800 180 0.5 m from base
5-element Yagi at 21.2 1000 10-20 In shack
60 ft
14 12 m from base
3-element Yagi at 28.5 425 8-12 12 m from base
25 ft
Inverted V at 7.23 1400 5-27 Below antenna
22-46 ft
Vertical on roof 14.11 140 6-9 In house
35-100 At antenna
tuner
Whip on auto roof 146.5 100 22-75 2 m from
antenna
15-30 In vehicle
90 Rear seat
5-element Yagi at 50.1 500 37-50 10 m from
20 ft antenna
Table 9.3--RF Awareness Guidelines
These guidelines were developed by the ARRL RF Safety Committee,
based on the FCC/EPA measurements of Table 9.2 and other data.
Although antennas on towers (well away from people) pose no
exposure problem, make certain that the RF radiation is confined
to the antennas' radiating elements themselves. Provide a single,
good station ground (earth), and eliminate radiation from transmission
lines. Use good coaxial cable, not open-wire lines or end-fed
antennas that come directly into the transmitter area.
No person should ever be near any transmitting antenna while
it is in use. This is especially true for mobile or ground-mounted
vertical antennas. Avoid transmitting with more than 25 W in a
VHF mobile installation unless it is possible to first measure
the RF fields inside the vehicle. At the 1-kW level, both HF and
VHF directional antennas should be at least 35 ft above inhabited
areas. Avoid using indoor and attic-mounted antennas if at all
possible.
Don't operate high-power amplifiers with the covers removed,
especially at VHF/UHF.
In the UHF/SHF region, never look into the open end of an
activated length of waveguide or point it toward anyone. Never
point a high-gain, narrow-bandwidth antenna (a paraboloid, for
instance) toward people. Use caution in aiming an EME (moonbounce)
array toward the horizon; EME arrays may deliver an effective
radiated power of 250,000 W or more.
With hand-held transceivers, keep the antenna away from your
head and use the lowest power possible to maintain communications.
Use a separate microphone and hold the rig as far away from you
as possible.
Don't work on antennas that have RF power applied.
Don't stand or sit close to a power supply or linear amplifier
when the ac power is turned on. Stay at least 24 inches away from
power transformers, electrical fans and other sources of high-level
60-Hz magnetic fields.
Focusing on frequency ranges from 100 kHz to 10 GHz, RF/Microwave Interaction with Biological Tissues is aimed at
medical applications. However, several of the chapters address fundamentals in Electromagnetics, the penetration
of RF/microwaves into biological tissues; the near field of an antenna; and microwave measurements.
This is a good practical book for anyone involved in RF safety work. There are
many useful references and illustrations. Topics include an introduction to RF and microwave
radiation, sources and effects of RF radiation, the development of safety standards,
calculation of RF field quantities, and more.
Tailored especially for the working health professional, this book is a practical guide
to understanding, evaluating, and controlling the human health effects of radio-frequency
(RF) and extremely low frequency (ELF) electromagnetic fields. Providing a perfect blend
of applied information and theory, you'll find all you need to know about radiation safety,
from the basic physics to how to set up a safety program.
