User's Manual

RF Exposure Limits
2 RF Exposure Limits
Various national and international RF regulations, safety standards, and
recommendations exist that are relevant to RBS RF exposure. The limits
defined in these standards are similar and are often based on international
guidelines set by the International Commission on Non-Ionizing Radiation
Protection (ICNIRP), which is recognized by the World Health Organization
(WHO). The guidelines have been incorporated in EU Council recommendation
1999/519/EC.
The ICNIRP has developed basic restrictions for both occupational and general
public exposure to electromagnetic fields that must not be exceeded in any
near-field or far-field exposure situation. These restrictions are based directly
on established health effects. The Specific Absorption Rate (SAR) is used to
specify the basic restrictions in the frequency range 10 MHz to 10 GHz. The
SAR is a measure of the rate of RF energy absorption by the body, expressed
in units of watts per kilogram of tissue (W/kg).
The restrictions are provided to prevent established adverse health effects
related to whole-body heat stress and excessive localized tissue heating.
Whole-body SAR is averaged over the whole body while localized SAR is
defined as the maximum local SAR averaged over any 10 g of tissue.
The restrictions, which are summarized in Table 1 on page 3 below, incorporate
a safety factor of about 10 for occupational exposure and about 50 for general
public exposure.
Table 1 ICNIRP Basic Restrictions for Occupational and General Public
Exposure
Whole-Body SAR (W/kg) Localized SAR 10g (W/kg)
(1)
Occupational
Exposure
General Public
Exposure
Occupational
Exposure
General Public
Exposure
0.4 0.08 10 2
(1) The limits provided on localized SAR are for head and trunk tissue. Localized SAR limits
for limbs are twice as high.
Reference levels are provided for the purpose of comparison with exposure
quantities in air. In the frequency range 10 MHz to 10 GHz the reference levels
are expressed as electric field strength (V/m), magnetic field strength (A/m),
and power density (W/m²). The ICNIRP power density reference levels for
occupational and general public exposure are summarized in Table 2 on page
4 and Table 3 on page 4 respectively.
3
124 46-EN/LZT 720 0399 Uen E 2008-09-29