RF energy that is radiated by wireless devices close to the user is partly absorbed by the human body and must not exceed safety limits. Devices that are used at a minimum of 20 cm’s distance from the human body need to pass RF exposure evaluation in the certification process. Based on the declared maximum transmit power and maximum antenna gain of the device, the power density at 20 cm's distance is calculated not to exceed the allowed levels.
Devices that are used also at a distance of less than 20 cm from the user must go through Specific Absorption Rate (SAR) testing in which the power absorbed by human tissue is measured.
RF exposure evaluation, SAR testing, and test reports are provided by several accredited test houses worldwide.