ICNIRP 1998 is a set of requirements established by ICNIRP, an internationally recognized standards body that defines guidelines for limiting EMF exposure. ICNIRP offers two classes of guidance: basic restrictions and reference levels. Basic restrictions are derived from established health effects. The qualities used to determine these restrictions are power density, current density and specific absorption rate (SAR). Reference levels are offered for use in practical exposure assessments to discover whether basic restrictions are being exceeded. These levels are derived from electric field strength, magnetic field strength, magnetic flux density power density and currents flowing through the limbs. ICNIRP 2010 is the most recent version of the standard and focuses on the frequency range of 1 Hz – 100 kHz.