1. What is the SAR 
   SAR is the English acronym for Specific Absorption Rate, is a measurement of the number of radio frequency radiation energy actually absorbed by the body was that of the unit, known as special absorption rate or SAR, in watts / kilogram (W / kg) or milliwatts / per gram (mW / g) to that. SAR is a radio-frequency energy radiation absorption rate measurement scale. 
   SAR accurate definition is: given the density of the material (ρ) under a unit volume (dV) units in the material (dm) absorption (loss) of the unit of electromagnetic energy (dW) compared with the time derivative, type the following: ( See Annex) 

     Of which: Ei cells for the tissue of the electric field strength RMS to V / m, said; 
     σ for the electrical conductivity of the human tissue in order to S / m, said; 
     ρ for human tissue density, said kg/m3; 
     Ci human tissue for the heat capacity to J / kg, said, 
     For the cells start time temperature derivative to K / s that 
2.SAR is generated? 
   At present, the international community are talking about the SAR, are directed at the cellular mobile phones (commonly known as mobile phones) generated by the radiation. As portable, mobile development very fast and very popular. Phone is a two-way radio equipment. When you use the phone call, it will pick up your voice and converted into radio frequency or radio waves. Radio waves passing through the air to a nearby base station receiver on. Then, base stations through the telephone network will call your phone to send you to call. Communication plans as follows: (see Annex) 

   When the phone call was launched to rely on a certain power of radio waves (RF), it is different from gamma rays, X-rays and electromagnetic spectrum, and other types of energy in the form of electromagnetic radiation is composed of electromagnetic energy from space in the electric and magnetic Mutual co-movement of energy, in the range of electromagnetic wave called. Radio radiation (RF) energy of a wide range of uses, telecommunications, radio, television, wireless phones, pagers, non-contact phone cards, police and fire department radio tool), point-to-point communication and satellite communications have come to rely on radio frequency radiation (RF) energy. Also includes the use of microwave ovens, radar, industrial heaters, iron, medical facilities and so on. Microwave radio frequency (RF) energy to hot water, cooking water to a large fast food; radar relies on radio (RF) to track cars and aircraft, and used for military purposes; industrial furnaces and the use of iron radio (RF) energy processing Forming plastic materials, bakelite products, such as sealing leather wallets and shoes, processed foods; radio (RF) energy for medical purposes, including monitoring and operation of the pacemaker. 
3. Phone call at the time of RF radiation on whether there is a physiological impact 
   It is clear that wireless phone calls during the launch of the radio waves can be exposed to the user's measurement of RF radiation, because when the phone call with the user's head very close. When the phone from the distant users, the radiation is very low, because the radiation source with the launch of the increase in distance will decay quickly. Cordless phone with "cordless phones", cordless phone calls because of the way with the houses of ordinary landline telephone exchange, communication is far less than the distance phone belonging to the typical low-power radio radiation, and the phone must have a certain amount of transmitting power. 
   Radio energy radiation on the human body and other types of biological effects of electromagnetic energy of impact is fundamentally different. High-energy level of electromagnetic energy, such as like X-rays and gamma rays can ionization of biological tissue. Was a ionization of the original e-escape where atoms and molecules. The results of the ionization can permanently damage biological tissues, including DNA and genetic material. Ionization occurred only in high-energy level of electromagnetic fields, such as X-rays and gamma rays. The range of radio frequency radiation, including radio waves and microwaves, other forms of non-ionizing radiation, including visible light, infrared and other types of low-frequency associated with electromagnetic radiation, the energy level is far below the rise of atomic and molecular Occurred need Ionizing great energy level. As a result, a strong exposure to radiation energy just to heat biological tissue and can damage biological tissue and body temperature. The two parts of the body, eyes and nose are particularly vulnerable to heat exposure to radiation attack, because there are relatively small capillaries of the transfer of surplus heat. The general public is usually encountered as a result of a number of radio energy radiation is very low, the heat will not be significant, will not lead to increased body temperature. For mobile phone radiation have really whether there is a hazard to human health are still in existence, the two diametrically opposed viewpoints, and the two views is a lack of evidence of clinical medicine. However, the industrial sector and the Government considered it necessary to propose a safety limit of the SAR, guiding production, at the same time, the standard-setting organizations and government agencies are continuing to master the latest scientific findings to determine whether or not to protect human health need to amend the limits of security Request. U.S. FDA, EPA and is responsible for public health and safety of other government agencies have been in cooperation with the World Health Organization (WHO) study on joint radio (RF) of human tissue will be what kind of impact on people and whether there are hazards. 
4. At present, widely used by the SAR limit is raised? 
   Organizations in different countries to allow exposure to radiation of radio energy under a different set of standards recommended for the general public of exposure to radiation workers, as well as the level of security. In the United States, since 1985, the Federal Communications Commission (FCC) has been implemented on the radio about the environmental radiation safety guidelines. Federal Communications Commission (FCC) on human exposure to RF electromagnetic fields against the guidelines from the specialized organizations of the two proposals, that is, "Radiation Protection and Measurements" (NCRP) and "Institute of Electrical and Electronics Engineers" (IEEE) . The two proposals are from industry, government and academic scientists and experts on the RF energy generated by biological effects of access to a large number of documents and materials into the preparation of the. 
   Europe and other parts of the country is "an international non-ionizing radio Protection Committee" (ICNIRP) guidelines for the development of radiation. Apart from a few exceptions, ICNIRP safety limit and the general provisions of the NCRP and IEEE similar. For example: ICNIRP recommendation of the low frequency range of different levels of exposure, as well as products (such as hand-held wireless phones) of exposure to the local level. At present, the World Health Organization (WHO) in the process of drafting an international coordinated framework of the RF safety standard (paper). 
   NCRP, IEEE and ICNIRP have on the (overall) did not produce harmful biological effects of radiation safety limits set at 4 watts / kilogram (4W/kg). Radiation exposure in a field guide, the power density and local absorption rate (SAR) said that the projects are derived from the limits of radiation. In addition, NCRP, IEEE, and also with the limits of ICNIRP exposure to RF frequency varies. This is because the human body's absorption of RF with the RF frequency changes and different. As far as possible to avoid human exposure to 30-300 MHz frequency range, because my wife experience in this area very effectively absorb RF energy. The only human radiation local products, such as wireless phones, only provides exposure limit (SAR). However, the frequency 300 kHz-100 GHz range of the transmitter, FCC was SAR, electric field strength, magnetic field intensity and power density exposure limit requirements. See the specific value of the FCC's two communiques (OET Bulletins 56 and 65). 
5. The world's major countries and regions of the SAR limits of the rules and methods of measurement 
The following table is the world's major countries and regions of the SAR limits of the rules and methods of measurement 
   Australia New Zealand USA Europe Japan and Taiwan international organizations 
Measurement of ACA (old) 
EN50361 (new) ANSI C95.3 
IEEE1528 EN50361 IEC62209 
(Draft) 
AS2772.1 limits 
ARPANSA NZS2772.1 ANSI C95.1 EN50360 TTC / MPT DGT ICNIRP 
The human body as a whole 0.08 W / kg 0.08 W / kg 0.08 W / kg 0.08 W / kg 0.04 W / kg 0.08 W / kg 0.08 W / kg 
Space peak 2 W / kg 2 W / kg 1.6 W / kg 2 W / kg 2 W / kg 1.6 W / kg 2 W / kg 
The average time for 6 min 6 min 30 min 6 min 6 min 30 min 6 min 
The average material 10g 10g 1g 10g 10g 1g 10g 
6. Headset with cell phones SAR to reduce the harm it? 
   Many cell phone users believe that the use of hands-free cell phone function will be to reduce the risk at this time that the phone away from his head, in fact, this is wrong. Hands-free features so that only the use of wireless phones more convenient and comfortable. Although the radiation source as a radio telephone is not directly in the head and leaning his head on a reduction of the exposure to radiation, but on the other hand, as the telephone at this time may be relying on the waist or other parts of the body will absorb more of the parts of the radio Radiation energy. In the wireless phones sold in the U.S. market, no matter when it is against the use of the head or other parts of the body, must be in compliance with the relevant safety requirements. And the structure must also be in line with the SAR limits. 
Some manufacturers believe that the structural design of an annex to the head shield will reduce the exposure to radiation. Research shows that radio waves because of the way of radiation, shielding his head did not clear the role of the annex, but because of "shielding" annex likely to interfere with the normal wireless phones, wireless phones may be forced to increase compensation for power, leading to increased exposure to radiation Absorption.