In today's industrial society, wireless devices that emit electromagnetic fields are increasingly used. National and international standards set limit values that should not be exceeded for health reasons.
The SAR factor tells us about the specific rate of energy absorption, i.e. the rate at which the energy radiated by the wireless communication device is absorbed by the human body.
This radiation can cause tissues to warm up, and in the case of appropriate values, to damage them. The most sensitive parts of the body outside the brain are eyes, which through poor blood supply relatively poorly discharge heat.
The measuring unit is wat / kg of tissue. In the case of near exposure, for example when using mobile phones, SAR limits refer to the maximum absorption of the average that occurs in the human body with a division into 1g or 10g tissue mass.
The maximum SAR level is defined by the administrative units of many countries. In the US, the FCC agency set the maximum SAR value at 1.6 W / kg, averaging over 1 gram of tissue. In Europe, this limit is 2 W / kg (measured on 10 grams of tissue).