Introduction to Health Physics: Fourth Edition - Ruang Baca FMIPA UB

NONIONIZING
RADIATION SAFETY
14
Nonionizing radiation (NIR) generally means electromagnetic radiation whose
quantum energy is less than 12 eV. However, although called “nonionizing” radiation,
photons whose energy is as low as 3 eV may ionize certain molecules; an electron
in a sodium atom, for example, requires only 2.3 eV of energy for its removal
from the atom.
Safety practices to control the hazards from NIR received little attention before
the end of World War II. At that time, we already had a good deal of experience with
damage to the eyes from observing solar eclipses, from exposure to ultraviolet (UV)
light among welders, and from exposure to infrared energy among glass blowers
and steelworkers. We also had evidence of damage to the skin from exposure to
UV and infrared radiation. However, it was the postwar boom in electronics and
communications, based on the microwave portion of the electromagnetic spectrum,
followed by the mushrooming use of lasers, that focused attention on the possible
public health aspects of NIR, especially from these two sources of radiant energy.
In 1968, the Radiation Control for Health and Safety Act (Public Law 90-602) was
passed by the U.S. Congress for the purpose of regulating the hazards from consumer
electronics products, and in 1970, the Occupational Safety and Health Act (PL 91-
596) was passed to protect workers from hazards, including ionizing and nonionizing
radiation hazards, associated with their occupations. These legislative acts, and acts
in other countries, have led to the promulgation of safety regulations for microwaves,
lasers, and UV radiation.
The International Commission on Radiological Protection (ICRP) limits its field
of interest to ionizing radiation. NIR, therefore, received relatively little attention
from the health physics community until the International Radiation Protection
Association (IRPA) revised its constitution in 1977 to expand its area of activities
to include NIR. The IRPA is a worldwide association of national radiation safety
societies (such as the Health Physics Society in the United States). Until the Fourth
International Congress in 1977, the IRPA dealt only with health and safety aspects
of ionizing radiation. At that meeting, the IRPA decided to expand its interests
to include the safe use of NIR. This expansion was immediately implemented by
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