Specific absorption rate

Specific Absorption Rate (SAR) is a measure of the rate at which radio frequency (RF) energy is absorbed by the body when exposed to radio-frequency electromagnetic field. The most common use is in relation to cellular telephones. In the United States, the Federal Communications Commission (FCC) has adopted limits for safe exposure to RF energy produced by mobile devices and requires that phones sold in the U.S. have a SAR level at or below 1.6 watts per kilogram (W/kg) taken over a volume of 1 gram of tissue. In the EU the corresponding limit is 2 W/kg, averaged over ten grams of tissue.