Depending on frequency, the following physical quantities are used to specify the reference levels of electric, magnetic, and electromagnetic fields (see also table “Reference levels”):
- 0 Hz (static fields) to 1 Hz:
Magnetic flux density (T), Magnetic field strength (A/m)
- 1 Hz to 10 MHz:
Magnetic flux density (T), Electric field strength (V/m), Magnetic field strength (A/m)
- 10 MHz to 300 GHz:
Magnetic flux density (T), Electric field strength (V/m), Magnetic field strength (A/m), Power density (W/m2).
The reference levels documented in the ICNIRP guidelines of 1998 and the EU Council Recommendation of 1999 were amended in the more recent ICNIRP guidelines of 2009, 2010 and 2014 for different frequency ranges between 0 Hz and 10 MHz. In Germany, the reference levels are valid according to the revised version of the 26. BlmSchV of 2013 (Ordinance on Electromagnetic Fields).
Table: Reference levels for electric, magnetic and electromagnetic fields in the frequency range 0 Hz - 300 GHz (general public), compiled from different ICNIRP guidelines (1998 - 2010) 
Special recommendations apply to pulsed signals (ICNIRP, p. 511, see note 5 in tables 6 and 7).
 Sources: ICNIRP: 1, 2, 3.
 Sources: ICNIRP: 4, 5.