One in a series of occasional articles to help AM radio
engineers and owners enhance their operations.
Many broadcast engineering
professionals are responsible for facility management and maintenance. If that
is your role, it is important to realize that the RF environment for which you
are answerable includes more than your primary transmissions. The overall electromagnetic
energy environment of your facility should be monitored as thoroughly as air
and water quality.
Electromagnetic energy is generated over a wide
spectrum of frequencies from many different sources. They include extremely
low frequency (ELF), radio frequency (RF) and microwave (MW) radiation,
generically referred to as “EMF.”
ELF fields are produced by power lines, electrical
wiring and electrical equipment. RF and MW radiation is emitted by your
broadcast transmitters, cellular phones, WiFi, microwave ovens, heat sealers,
high-frequency welders, induction heaters, flow solder machines, communications
transmitters, radar transmitters and many other sources.
These frequencies, along with visible
and ultraviolet light, are known as non-ionizing radiation to distinguish them
from the more dangerous X-rays, gamma rays and other higher energy level rays,
which are known as ionizing radiation. (Ionizing radiation is not addressed
here but may be a factor if you operate circuits with very high voltage in TV
or shortwave transmitters.)
Standards have been set for acceptable electromagnetic
energy levels. The American National Standards Institute (ANSI) and the
Institute of Electrical and Electronics Engineers (IEEE) have studied and
identified acceptable intensity and exposure upper limits.It is your responsibility to identify and document the
electromagnetic environment to ensure that your workplace and the general
public are appropriately protected from excessive EMF exposure.
The FCC has established maximum
permissible exposure (MPE) levels for human exposure to RF. The commission
also has published guidelines and procedures for evaluating RF health exposure.
While the focus of the FCC is strictly on transmitters it licenses, OSHA is
very much concerned with the workplace. OSHA has published its own guidelines
that agree with those of the FCC, but go beyond them in a number of areas.
Industry Canada standards are similar to OSHA.
The General Duty Clause of OSHA states
that an employer is required “to furnish to each of his employees, employment
and a place of employment which are free from recognized hazards that are
causing or are likely to cause death or serious physical harm to his employees.”
High EMF levels in and around your broadcast facility can affect the general
population and, specifically, at-risk individuals.
But potentially hazardous exposure to
non-ionizing radiation is a possibility in thousands of occupational
situations, with commercial and industrial radiation applications outside the
broadcast industry continuing to grow. What’s more, in addition to effects
on humans, RF energy can interfere with other electronic equipment such as
computer systems, wireless devices, RFID systems and medical equipment
(defibrillators, pacemakers, infusion pumps, to name a few). Often, these
types of equipment are vital to providing workplace or public safety.
As with all environmental concerns, the
electromagnetic environment is a risk management issue. By recognizing it as
such, a facility manager has taken a positive step toward protecting employees,
visitors, and the public as well as avoiding potential litigation should an
Few businesses can operate in isolation
today, and the lines between safety and mission-critical operations sometimes
are blurred. Note that FCC regulations are “health effect” rules, whereas OSHA
rules are “workplace safety” rules. There is a world of difference. Then there
are lawyer’s rules, which are that “any harm or claim of harm can be litigated”
— often at great cost!
Welcome to the world of EMF risk
management, where you really need to have radiation safety procedures in place.
For more on this topic, see the RF Safety tab under Columns at
Lawrence Behr is founder of Lawrence Behr Associates and RF
equipment manufacturer LBA Technology. A former radio and TV station owner, he
was a founding member of the Society of Broadcast Engineers. Find past articles
at radioworld.com, keyword Behr.