Introduction to RF Radiation Safety / 7 / 7.6 / 7.6.2

7.6.2 Basic Restrictions And Reference Levels

7.6.2.1 Basic Restrictions

Basic restrictions apply to quantities within or at the surface of the body that are closely related to established adverse effects. They are the primary health-based limits and must not be exceeded.

The relevant quantity depends on frequency, duration, and spatial extent. Induced electric-field strength is used where electrostimulation is relevant; whole-body and localized specific absorption rate describe absorbed power per unit mass; specific energy absorption addresses brief localized exposure; and absorbed power density and absorbed energy density are used for localized exposure above 6 GHz.

These quantities describe different aspects of RF dosimetry and are not interchangeable. As Chapter 6 emphasized, there is no single universal RF dose. Table 7.1 provides a concise reminder of the principal internal basic restriction quantities; the detailed definitions and frequency ranges are given in Chapter 6.

7.6.2.2 Reference Levels

Reference levels provide a practical means of assessing exposure using quantities that can generally be measured or calculated more readily than internal dosimetric quantities—see Table 7.2. Depending on frequency and exposure conditions, these include incident electric- and magnetic-field strengths, incident power or energy density, plane-wave-equivalent quantities, and current in the limbs.

Reference levels are derived conservatively from the basic restrictions. Compliance with the applicable reference level demonstrates compliance with the corresponding basic restriction. Exceeding a reference level does not necessarily mean that a basic restriction has been exceeded or that an adverse health effect will occur; it indicates that a more detailed assessment is required.

Contact-current and spark-discharge hazards remain important indirect safety considerations, but ICNIRP 2020 does not provide numerical contact-current reference levels. These hazards must be controlled using the applicable safety guidance, engineering controls, and any relevant workplace or equipment standards.