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THERMAL EFFECTS EXPOSURE LIMIT VALUES AND ACTION LEVELS IN THE FREQUENCY RANGE FROM 100 kHz TO 300 GHz A. EXPOSURE LIMIT VALUES (ELVs) Health effects ELVs for frequencies from 100 kHz to 6 GHz (Table A1) are limits for energy and power absorbed per unit mass of body tissue generated from exposure to electric and magnetic fields. Sensory effects ELVs for frequencies from 0,3 to 6 GHz (Table A2) are limits on absorbed energy in a small mass of tissue in the head from exposure to electromagnetic fields. Health effects ELVs for frequencies above 6 GHz (Table A3) are limits for power density of an electromagnetic wave incident on the body surface. Table A1 Health effects ELVs for exposure to electromagnetic fields from 100 kHz to 6 GHz Health effects ELVs SAR values averaged over any six-minute period ELVs related to whole body heat stress expressed as averaged SAR in the body 0,4 Wkg–1 ELVs related to localised heat stress in head and trunk expressed as localised SAR in the body 10 Wkg–1 ELVs related to localised heat stress in the limbs expressed as localised SAR in the limbs 20 Wkg–1

Note A1-1: Localised SAR averaging mass is any 10 g of contiguous tissue; the maximum SAR so obtained should be the value used for estimating exposure. This 10 g of tissue is intended to be a mass of contiguous tissue with roughly homogeneous electrical properties. In specifying a contiguous mass of tissue, it is recognised that this concept may be used in computational dosimetry but may present difficulties for direct physical measurements. A simple geometry, such as cubic or spheric tissue mass, can be used. Sensory effects ELVs from 0,3 GHz to 6 GHz This sensory effects ELVs (Table A2) is related to avoiding auditory effects caused by exposures of the head to pulsed microwave radiation. Table A2 Sensory effects ELVs for exposure to electromagnetic fields from 0,3 to 6 GHz Frequency range Localised specific energy absorption (SA) 0,3 ≤ f ≤ 6 GHz 10 mJkg–1 Note A2-1: Localised SA averaging mass is 10 g of tissue. Table A3 Health effects ELVs for exposure to electromagnetic fields from 6 to 300 GHz Frequency range Health effects ELVs related to power density 6 ≤ f ≤ 300 GHz 50 Wm–2

Note A3-1: The power density shall be averaged over any 20 cm2 of exposed area. Spatial maximum power densities averaged over 1 cm2 should not exceed 20 times the value of 50 Wm–2. Power densities from 6 to 10 GHz are to be averaged over any six-minute period. Above 10 GHz, the power density shall be averaged over any 68/f1,05-minute period (where f is the frequency in GHz) to compensate for progressively shorter penetration depth, as the frequency increases. B. ACTION LEVELS (ALs) The following physical quantities and values are used to specify the action levels (ALs), the magnitude of which are established to ensure by simplified assessment the compliance with the relevant ELVs or at which relevant protection or prevention measures specified in Article 5 must be taken:

— ALs(E) for electric field strength E of time varying electric field, as specified in Table B1;

— ALs(B) for magnetic flux density B of time varying magnetic field, as specified in Table B1;

— ALs(S) for power density of electromagnetic waves, as specified in Table B1;

— ALs(IC) for contact current, as specified in Table B2;

— ALs(IL) for limb current, as specified in Table B2;

ALs correspond to calculated or measured field values at the workplace in the absence of the worker, as maximum value at the position of the body or specified part of the body. Action levels (ALs) for exposure to electric and magnetic fields ALs(E) and ALs(B) are derived from the SAR or power density ELVs (Tables A1 and A3) based on the thresholds related to internal thermal effects caused by exposure to (external) electric and magnetic fields. Table B1 ALs for exposure to electric and magnetic fields from 100 kHz to 300 GHz Frequency range Electric field strength ALs(E) [Vm–1] (RMS) Magnetic flux density ALs(B) [μT] (RMS) Power density ALs(S) [Wm–2] 100 kHz ≤ f < 1 MHz 6,1 × 102 2,0 × 106/f — 1≤ f < 10 MHz 6,1 × 108/f 2,0 × 106/f — 10 ≤ f < 400 MHz 61 0,2 — 400 MHz ≤ f < 2 GHz 3 × 10–3 f½ 1,0 × 10–5 f½ — 2 ≤ f < 6 GHz 1,4 × 102 4,5 × 10–1 — 6 ≤ f ≤ 300 GHz 1,4 × 102 4,5 × 10–1 50 Note B1-1: f is the frequency expressed in hertz (Hz).

Note B1-2: [ALs(E)]2 and [ALs(B)]2 are to be averaged over a six-minute period. For RF pulses, the peak power density averaged over the pulse width shall not exceed 1 000 times the respective ALs(S) value. For multi-frequency fields, the analysis shall be based on summation, as explained in the practical guides referred to in Article 14. Note B1-3: ALs(E) and ALs(B) represent maximum calculated or measured values at the workers’ body position. This results in a conservative exposure assessment and automatic compliance with ELVs in all non-uniform exposure conditions. In order to simplify the assessment of compliance with ELVs, carried out in accordance with Article 4, in specific non-uniform conditions, criteria for the spatial averaging of measured fields based on established dosimetry will be laid down in the practical guides referred to in Article 14. In the case of a very localised source within a distance of a few centimetres from the body, compliance with ELVs shall be determined dosimetrically, case by case.

Note B1-4: The power density shall be averaged over any 20 cm2 of exposed area. Spatial maximum power densities averaged over 1 cm2 should not exceed 20 times the value of 50 Wm–2. Power densities from 6 to 10 GHz are to be averaged over any six-minute period. Above 10 GHz, the power density shall be averaged over any 68/f1,05-minute period (where f is the frequency in GHz) to compensate for progressively shorter penetration depth as the frequency increases. Table B2 ALs for steady state contact currents and induced limb currents Frequency range Steady state contact current, ALs(IC) [mA] (RMS) Induced limb current in any limb, ALs(IL) [mA] (RMS) 100 kHz ≤ f < 10 MHz 40 — 10 ≤ f ≤ 110 MHz 40 100 Note B2-1: [ALs(IL)]2 is to be averaged over a six-minute period.