SAR, or Specific Absorption Rate, is a measure of the rate at which energy is absorbed by the human body when exposed to electromagnetic fields, particularly radiofrequency (RF) radiation emitted by wireless devices such as smartphones, tablets, and wireless routers. SAR is typically expressed in watts per kilogram (W/kg).

Key points about SAR include:

  1. Safety Standard: SAR is used to assess and regulate the potential health risks associated with exposure to RF radiation. Regulatory agencies in various countries have established SAR limits to ensure that wireless devices comply with safety guidelines.
  2. Measurement: SAR is measured by conducting laboratory tests with a model of the human head and body. A device is positioned at various distances from the model, and the rate at which energy is absorbed by the model’s tissues is recorded.
  3. Limit Values: Different countries or regions may have their own SAR limits for wireless devices. These limits are typically based on recommendations from organizations like the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Federal Communications Commission (FCC) in the United States.
  4. SAR Ratings: Smartphone manufacturers often provide SAR ratings for their devices, indicating the maximum SAR values measured during testing. These values can usually be found in the device’s user manual or on the manufacturer’s website.
  5. Head and Body SAR: SAR values are typically provided for both head and body exposure. The head SAR is relevant when the device is held close to the head, such as during phone calls, while the body SAR is relevant when the device is carried on the body, such as in a pocket.
  6. Safety Precautions: While SAR values are used to assess safety, it’s important to note that they represent the maximum exposure under laboratory conditions. In everyday use, factors like distance from the device, signal strength, and duration of exposure can all influence actual exposure levels.
  7. Lowest Possible SAR: Manufacturers design devices to operate at the lowest SAR levels possible while maintaining functionality and signal quality.

It’s important for users to be aware of SAR values and take precautions, such as using hands-free accessories or speakerphone mode during phone calls, to minimize RF exposure, especially if they have concerns about potential health effects. Overall, regulatory agencies and organizations continuously monitor and update guidelines to ensure the safety of wireless technologies.