SAR

The SAR, or specific absorption rate, of a mobile phone is the amount of RF energy it exposes its user to. In the United States, mobile phones need to have a SAR rating of 1.6 watts per kilogram (W/kg) or less. In Europe, the limit is 2 W/kg. While there have been plenty of studies that conclude that phone based RF radiation is harmful, there are an equal amount that find the opposite to be true. In any event, a device with a lower SAR rating will pose less of a risk than one with a higher rating.