ETS-Lindgren HI-3637 VLF Magnetic Field Meter - Manual (Page 45)

HI n 3637 Manual Page — 37
GUIDELINES FOR RF EXPOSURE
To provide a means for judging the significance of
measured magnetic field emissions found near VDT's, the
scientific literature can be examined for information on
suggested exposure or emission limits. The exposure
standards reviewed at the time of this manual's
preparation apply to humans for the purpose of
establishing safe working or living environments where
magnetic fields exist. The exposure limits compiled in
this manual are those found that correspond most closely
to the predominant frequency range of VDT's. In some
cases, the standards apply to occupational exposure
environments and in other cases, to the general living
environment; often standards for this latter case are
referred to as general population or public exposure limits.
Traditional approaches to radiation protection, principally
derived from ionizing radiation protection practices,
usually differentiate between occupational and public
exposure. Generally, occupational exposure limits are
higher, i.e., more permissive, than public limits. This is
because of the greater uncertainties associated with the
general public; in the work place, employees are generally
healthier, and possible exposure to potentially hazardous
physical agents is usually under much better control. For
example, employers can inform workers of situations
which should be avoided; this is not the case for the
general population. Regardless of these considerations,
it is informative to examine some of the recommended
exposure guides that apply to different organizations
and/or countries.
Table 1 summarizes the electromagnetic field exposure
standards found in the literature that either directly apply
to the frequency range appropriate to VDT emissions or
pertain to a frequency range close to that of interest. As
can be seen, the primary difficulty in applying many RF
exposure standards to VDT emission levels is that the
applicable frequency range of the standards does not
extend low enough. From the literature searched, only
one reference was found that offered a quantitative
emission limit as a guideline specific to VDT's (Telecom,