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Safety and Electromagnetic Field Guidelines

Local absorbed power density (>6 GHz to 300 GHz): For local exposure for both the Head and Torso

and Limb regions (6 GHz to 300 GHz), an absorbed power density (Sab) limit averaged over 6 minutes

and a square 4 cm² surface area of the body was set for the local temperature rise of 5°C or 2°C depend­

ing on tissue type in Table 7.5. Furthermore, to account for focal beam exposure from 30 to 300 GHz, the

absorbed power density averaged over a square 1 cm² surface area of the body must not exceed two times

that of the 4 cm² basic restrictions for workers or the general public.

Local absorbed energy density (>6 GHz to 300 GHz): In addition, for frequencies from 6 to 300 GHz,

ICNIRP sets an additional limit expressed as local absorbed energy density (Uab) for exposure intervals

of <6 minutes, as a function of time, to ensure that the cumulative energy permitted by the 6-minute

average absorbed power density basic restriction is not absorbed by tissues too rapidly in Table 7.6.

In ICNIRP 2020, the basic restrictions of SAR remain unchanged; the basic restriction, which was

expressed in terms of spatial power density at 10–300 GHz, is now expressed in terms of Sab, the locally

absorbed power density absorbed by tissues near the body surface. Basic restriction for local exposure is

now expressed in terms of local SAR for the frequency range of 100 kHz to 6 GHz and local Sab for the

frequency range of 6–300 GHz. On the other hand, the basic restrictions for induced electric feld into

the body from 100 kHz to 10 MHz are the same as in ICNIRP 2010.

7.8.1.2 Reference Level

In ICNIRP 2020, reference levels are presented in terms of electric feld strength (V/m), magnetic feld

strength (A/m), power density (W/m²), and induced current (mA) to the extremities, in the frequency

range from 100 kHz to 300 GHz. Reference levels shown in Tables 7.7–7.9 have been derived from the

basic restrictions by a combination of computational and measurement studies for worst-case exposure

scenarios.

TABLE 7.7 Reference Levels in ICNIRP Guidelines for Exposure, Averaged over 30 Minutes and the Whole Body,

to Electromagnetic Fields from 100 kHz to 300 GHz (Unperturbed rms Values)

Exposure

Scenario

Frequency Range

Incident E-Field

Strength; Einc (V/m)

Incident H-Field

Strength; Hinc (A/m)

Incident Power

Density; Sinc (W/m²)

Occupational

0.1–30 MHz

>30–400 MHz

0.7

660/fM

61

4.9/fM

0.16

NA

10

>400–2000 MHz

>2–300 GHz

0.5

3fM

NA

0.5

0.008fM

NA

fM/40

50

General

public

0.1–30 MHz

>30–400 MHz

>400–2,000 MHz

>2–300 GHz

0.7

300/fM

27.7

0.5

1.375fM

NA

2.2/fM

0.073

0.5

0.0037fM

NA

NA

2

fM/200

10

Source: Reproduced from ICNIRP, Health Physics 118:483–524, 2020.

Notes:

1. “NA” signifes “not applicable” and does not need to be taken into account when determining compliance.

2. fM is frequency in MHz.

3. Sinc, Einc, and Hinc are to be averaged over 30 minutes, over the whole-body space. Temporal and spatial averaging of each

of Einc and Hinc must be conducted by averaging over the relevant square values.

4. For frequencies of 100 kHz to 30 MHz, regardless of the far-feld/near-feld zone distinctions, compliance is demonstrated

if neither Einc or Hinc exceeds the above reference level values.

5. For frequencies of >30 MHz to 2 GHz: (a) within the far-feld zone: compliance is demonstrated if either Sinc, Einc or Hinc,

does not exceed the above reference level values (only one is required); Seq may be substituted for Sinc; (b) within the radia­

tive near-feld zone, compliance is demonstrated if either Sinc, or both Einc and Hinc, does not exceed the above reference

level values; and (c) within the reactive near-feld zone: compliance is demonstrated if both Einc and Hinc do not exceed the

above reference level values; Sinc cannot be used to demonstrate compliance, and so basic restrictions must be assessed.

6. For frequencies of >2 GHz to 300 GHz: (a) within the far-feld zone: compliance is demonstrated if Sinc does not exceed

the reference level values; Seq may be substituted for Sinc; (b) within the radiative near-feld zone, compliance is demon­

strated if Sinc does not exceed the above reference level values; and (c) within the reactive near-feld zone, reference levels

cannot be used to determine compliance, and so basic restrictions must be assessed.