The difference between head and body SAR value is an important question to consider when purchasing a cellular device. SAR stands for Specific Absorption Rate, and is a measure of the rate of energy produced by the body’s absorption of the electromagnetic radiation that emanates from a device. The SAR value is expressed in watts per kilogram (W/kg), and is divided into two categories – head and body. The SAR value for the head specifically, generally has a higher value than the body SAR value.
Introduction
When it comes to exposure to electromagnetic radiation, the Specific Absorption Rate (SAR) is a measure of the rate of energy absorption by the human body. This measure is used to evaluate the safety of products that emit electromagnetic radiation, such as cell phones and wireless devices. SAR values are expressed in watts per kilogram (W/kg). There are two types of SAR values: head SAR and body SAR. It is important to understand the differences between the two to ensure safety in our use of electronic devices.
Body SAR vs. Head SAR
The primary difference between body SAR and head SAR is the area of the body that is being measured. Body SAR is measured over the whole body, including the head, and is the most commonly referenced SAR value. It is the maximum SAR value that can be measured when the device is held at the ear, and is the one specified by the manufacturer. Head SAR, on the other hand, is specifically measured on the head only and is the maximum SAR value that can be measured when the device is held at a distance of 5 mm from the head.
Safety
The safety of SAR values is based on the amount of energy that is absorbed by the body. The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has established Guidelines for Maximum Permissible Exposure (MPE) limits for radio frequency (RF) energy, indicating the highest level of exposure to radio waves that a person can be exposed to without any adverse health effects. According to these guidelines, the maximum permissible SAR value for body SAR is 2 W/kg, while the maximum permissible SAR value for head SAR is 1.6 W/kg.
Testing
The SAR values of electronic devices are tested in laboratories to ensure that they meet the safety guidelines. The testing process involves placing the device in a container filled with liquid that simulates the human body and measuring the amount of energy absorbed by the liquid. The test results are then used to calculate the SAR values for both body and head SAR.
Conclusion
Understanding the differences between body SAR and head SAR is important for ensuring the safety of our use of electronic devices. Body SAR is measured over the whole body, including the head, and is the most commonly referenced SAR value. Head SAR is specifically measured on the head only and is the maximum SAR value that can be measured when the device is held at a distance of 5 mm from the head. The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has established Guidelines for Maximum Permissible Exposure (MPE) limits for radio frequency (RF) energy, indicating the highest level of exposure to radio waves that a person can be exposed to without any adverse health effects. It is important to be aware of the SAR values of electronic devices to ensure that they are within safe limits.
