To communicate with the network, mobile phones emit low levels of radio waves (also known as radiofrequency or 'RF' energy) when being used. SAR stands for Specific Absorption Rate, which is the unit of measurement for the amount of RF energy absorbed by the body when using a mobile phone.
The SAR is determined at the highest certified power level in laboratory conditions.
A SAR value is a measure of the maximum energy absorbed by a unit of mass of exposed tissue of a person using a mobile phone, over a given time or more simply the power absorbed per unit mass. SAR values are usually expressed in units of watts per kilogram (W/kg) in either 1g or 10g of tissue.
You should also be aware that the SAR values shown are maximum values and in practice emissions from mobile phones will normally be lower than these figures. The emissions depend on factors such as distance from a transmission mast, whether the phone is used indoors or outdoors, how close the phone is held to the ear and other operating factors. It is important to realise that a phone with a high SAR rating may actually operate with much lower emissions in practice, and conversely a phone with a lower SAR rating may operate with emissions higher than a high SAR phone in practice. You should not rely on a low SAR rating to guarantee your health.
Exposure Limits
North American and Australian Standard - The SAR limit for mobile phones used by the public is 1.6 watts/kilogram (W/kg) averaged over one gram of body tissue.
European Standard - The SAR limit for mobile phones used by the public is 2.0 watts/kilogram (W/kg) averaged over ten grams of body tissue.
To compare relative radiation of different mobile phones, only compare phones using the same standard.
Does the SAR for a mobile phone vary when in use?
Yes. Although the SAR is determined at the highest certified power level in laboratory conditions, the actual SAR level of the phone while operating can be well below this value. This is because mobile phones use adaptive power control to reduce the transmitted power to the minimum possible whilst maintaining good call quality.
Once a call is established the mobile phone will power down to the minimum level required. Therefore, the closer you are to a base station and the better the reception, the lower the actual SAR level.
Does SAR vary between mobile phones?
Yes. The maximum SAR level for different mobile phone models can vary and this is primarily due to where the antenna in the phone is located.
Where can i find the SAR and safety information for mobile phones?
There are many ways to find SAR information for mobile phones.
Check the phone handbook or user manual – look under safety or specifications
Search the manufacturer’s web site for your phone model and SAR – it is usually listed under safety, or product specifications.
If everything fails, Google it
How is SAR measured for mobile phones?
Specialised laboratory test equipment is used for conducting SAR measurements. The equipment consists of a ‘phantom’ (human or box), precision robot, RF field sensors, and mobile phone holder. The phantom is filled with a liquid that represents the electrical properties of human tissue.
Head Measurements - SAR test inside a head phantom:
The mobile phone is positioned against the phantom head and switched on to full power.
The precision robot moves the RF probe throughout the phantom head measuring the radio signal level in the head phantom.
The computer analysing the data converts the radio signal levels into SAR (W/kg).
The full test is conducted at all operating frequencies and using different phone positions.
The maximum level measured is recorded as the SAR value against the head.
Body Measurements - SAR test inside a body (box) phantom:
The mobile phone is positioned against the phantom body and switched on to full power.
The precision robot moves the RF probe throughout the phantom body measuring the radio signal level in the body near the phone.
The computer analysing the data converts the radio signal levels into SAR (W/kg).
The maximum level measured is recorded as the SAR value against the body.
Check out the SAR measurement video here !
Is there a separation distance from the body required for mobile phones?
Mobile phones generally get better reception when used away from the main part of the body. Some mobile phones are designed to have a small minimum separation from the body when in use, typically 15 – 25mm depending on the phone. The minimum separation often represents the spacing created by a phone holder or clothing. This is to ensure the phone operates more efficiently and also meets the SAR requirements.
A mobile phone can always be used up against the head without separation. This is because the antenna in the phone is designed to be far enough away from the head to meet SAR requirements and operate most efficiently.
Am I at risk by not using a separation distance?
Separation distances are used for more efficient operation of the phone and for SAR compliance. If a separation distance is specified and not adopted then the phone is possibly being used in a non-compliant position. However this does not compromise safety as the international exposure guidelines have large built-in safety margins.
How to reduce your exposure to phone radiation
Use a hands-free headset.
Do not use your phone more than necessary and keep your calls short
Send a text instead of making a call
Try to avoid using your phone if the signal strength is low - find a better location to make a call
Try to use the phone outdoors rather than inside, or move close to a window to make a call
Keep the phone (and particularly the aerial) as far as possible from your head
Avoid touching the aerial while the phone is turned on, and keep the phone away from areas of the body such as eyes, testicles, breasts and internal organs
Women - Limit usage as much as possible if pregnant
Switch off your phone when not in use
MMF (Mobile Manufacturer Forum) has recently released a video on the issue, you can view it here
Samsung users check your SAR value here
Nokia users can check their phone's SAR value here
Motorola here
Sourced part of the info from EMF Explained. Image courtesy - Think Digit.