*#07# SAR value meaning and it’s limit.

Many of us would have tried this code on our phones and the phone returned some head and body SAR values but what do they actually mean and what is the limit of the SAR value?

According to Wikipedia;

“Specific Absorption Rate (SAR) is a measure of the rate at which energy is absorbed per unit mass by a human body when exposed to a radio frequency (RF) electromagnetic field. It can also refer to the absorption of other forms of energy by tissue, including ultrasound. It is defined as the power absorbed per mass of tissue and has units of watts per kilogram (W/kg).

When measuring the SAR due to a mobile phone the phone is placed against a representation of a human head (a "SAR Phantom") in a talk position. The SAR value is then measured at the location that has the highest absorption rate in the entire head, which in the case of a mobile phone is often as close to the phone's antenna as possible. Measurements are made for different positions on both sides of the head and at different frequencies representing the frequency bands at which the device can transmit. Depending on the size and capabilities of the phone, additional testing may also be required to represent the usage of the device while placed close to the user's body and/or extremities.”

In simple words, SAR values that our phone shows on typing the above code is that the value measured by the manufacturer should be under limit according to the guideline of the country which I will tell you afterward. SAR testing uses standardized models of the human head and body that are filled with liquids that simulate the RF absorption characteristics of different human tissues. The phone is precisely placed in various common positions next to the head and body, and a robotic probe takes a series of measurements of the electric field at specific pinpoint locations in a very precise, grid-like pattern within the dummy head and torso. The phone is kept at its highest power in all frequency bands and imitated like humans hold the phone in a different position. Then the frequency absorbed by the head and body is noted down and checked if it falls under FCC’s RF guidelines.

Effects of radiation on human health if it’s out of limit:

If precaution is not taken the cell phone/tower can act as a cigarette which can cause health problems in the long run.

The most common complaints are sleep disorder, headache, irritability, concentration problems, memory loss, depression, hearing loss, joint problems, etc. More severe reactions include seizures, paralysis, miscarriage, irreversible infertility, and cancer. Children and pregnant ladies are more vulnerable.

  • Children’s brains absorb double the radiation on average of an adult brain, and SAR levels are based on an adult brain.

  • SAR levels only give us information about how much radiation they emit when in use against the body, but do not tell us about how much radiation they emit when not in use. For example, cell phones and computers can have a significant impact on male fertility due to constant EMF exposure.

  • The dummies that are used for testing, only contain liquid. Many people have metal fillings, earrings, wear glasses, etc. and all of these can impact how the radiation is absorbed and amplified.

Limitation of SAR value:

  • United States: the FCC requires that phones sold have a SAR level at or below 1.6 watts per kilogram (W/kg) taken over the volume containing a mass of 1 gram of tissue that is absorbing the most signal.

  • European Union: CENELEC specifies SAR limits within the EU, following IEC standards. For mobile phones and other such hand-held devices, the SAR limit is 2 W/kg averaged over the 10 g of tissue absorbing the most signal.

  • India: switched from the EU limits to the US limits for mobile handsets in 2012. Unlike the US, India will not rely solely on SAR measurements provided by manufacturers; random compliance tests are done by a government-run Telecommunication Engineering Center (TEC) SAR Laboratory on handsets and 10% of towers. All handsets must have a hands free mode.

In India, the regulatory unit is 1.6 W/kg.

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