# Specific absorption rate

Wireless devices are increasingly ubiquitous in our daily lives, ranging from smartphones and Wi-Fi routers, to Bluetooth headsets and tablets. With more Canadians than ever relying on wireless-enabled products and services, the proliferation of radiofrequency-emitting devices is ever increasing.

However, demand for wireless services has to be balanced with the safety of Canadians. Consequently, all equipment manufactured, imported, sold or leased in Canada must meet stringent radiofrequency exposure requirements.

Innovation, Science and Economic Development Canada also monitors cellular and broadcasting towers to ensure that such installations also meet Safety Code 6 requirements. Further information on tower safety can be found at the Innovation, Science and Economic Development Canada's Fact about Tower web site.

Large safety margins, of the order of 50 times in many cases, are built into Safety Code 6 to provide a significant level of protection for anyone using a wireless device. As such, the safety of Canadians is ensured when using any compliant wireless device in Canada.

### What is SAR?

The Specific Absorption Rate or SAR is the rate at which RF energy is absorbed by a defined amount of mass of a biological body. SAR is expressed in units of watts per kilogram (W/kg). The SAR value of your cell phone is normally published in the user manual or you can contact the manufacturer to obtain this information. The SAR value can also be obtained on Innovation, Science and Economic Development Canada’s website (see Question 5)

Innovation, Science and Economic Development Canada requires that all portable and hand-held radiocommunication devices sold in Canada, including cell phones, comply with the regulatory SAR limits.

### What are the SAR limits in Canada?

Table 1: SAR Limits in Canada
Body Region Devices Used by the General Public
SAR Limit (W/kg)
Devices for Controlled Use
SAR Limit (W/kg)
Mass Average (g)
Localized Head and Trunk 1.6 >8 1
Localized Limbs 4 20 10

For example, the SAR limit for general public for a cell phone in close proximity to the head and trunk is 1.6 W/kg, averaged over any 1g of tissue.

### Are the SAR limits the same around the world?

Canada and the US have similar SAR limits. However, other countries, such as those in the European Community, have adopted the less stringent limit recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guideline.

Table 2: SAR Limits for head, neck and trunk in Canada/US versus ICNIRP
Guideline SAR limit - Head, Neck and Trunk
US FCC OET 65
1.6 W/kg averaged over 1 gram of tissue*
ICNIRP 2.0 W/kg average over any 10 grams of tissue**
* Defined as tissue volume in the shape of a cube
** Defined as 10g of continuous tissue

Averaging localized SAR using a larger volume allows greater variation within the sample that could permit exposure to higher levels of RF at some points within the sample. Confining the average SAR to a smaller sample allows less variability and overall lower allowable exposure to RF; thus, making the SAR limit adopted in North America more stringent in comparison to the ICNIRP limit (adopted by most of Europe).

### Is a cell phone with a lower SAR value considered safer?

No. Different cell phones will have different SAR values;, however, all must meet the regulatory limits set forth by Innovation, Science and Economic Development Canada in order to be sold on the Canadian market. These established regulatory limits are well below any levels that could represent a safety concern.

### How can I obtain the SAR value of my cell phone on the Innovation, Science and Economic Development Canada website?

The SAR value of a specific cell phone model can be obtained for almost all cell phones by using the Innovation, Science and Economic Development Canada (IC) Certification Number for that model. The IC Certification Number is an alpha-numeric code typically printed on a label or embossed, somewhere on the case or in the battery compartment of the phone or device. Once the IC Certification Number is obtained, you must enter it in the Certification Number criteria field in the Radio Equipment List (REL) database search page.

Click on "Search" and the phone model will appear. Click on the phone model and you should obtain the applicable SAR value(s) for your phone as measured at time of certification.

### How do you measure SAR?

The cell phone is made to continuously transmit at maximum output power into the simulated human body/head tissue. The maximum electric field, as a result of radiated emissions from the cell phone is then measured in and around the simulated tissue. This test determines the maximum SAR associated with the phone or device.

SAR measurement methodologies are developed by international standards development organizations such as the Institute of Electrical and Electronics Engineers (IEEE) and the International Electrotechnical Commission (IEC). The international standards developed by these organizations provide measurement methods to test portable and hand-held devices such as cell phones for compliance with Specific Absorption Rate (SAR) limits. These measurement methods are recognized world-wide as procedures for verifying Radio Frequency (RF) exposure compliance.

Since the SAR value is determined at the highest power level in laboratory conditions, the actual SAR level of the cell phone can be well below this value when operating in every day use. Cell phones and other portable devices use adaptive power control to reduce the transmitted power to the minimum possible while maintaining a good call quality. This is an important feature which is used to maximize battery life.

Specialised laboratory test equipment is used for conducting SAR measurements. The equipment consists of a ‘phantom’ (human or body), precision robot, RF field sensors, and device holder. The phantom is filled with a liquid that represents the electrical properties of human tissue.

Figure 1: SAR measurement systems at Innovation, Science and Economic Development Canada Certification and Engineering Bureau.

Two basic types of SAR measurement are made: head measurement when the device is used near the head and, body measurement when the device is used near or in contact with the body. A simplified example of the steps taken to measure SAR applied to a cell phone is provide below. Note that similar procedures are also used for other type of devices using RF such as tablets, WiFi routers, land mobile radio, etc.

For head measurements, a head phantom is used and the following steps are followed:

• The cell 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 cell phone signal level in the head phantom.
• The computer analysing the data converts the radio signal of the cell phone 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.

For body measurements, a body (box) phantom is used and the following steps are followed:

• The cell phone is positioned at a distance of 15mm or less from 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 cellular 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.

### What has changed as a result of the revised Safety Code 6 in March 2015?

Health Canada has updated Safety Code 6 based on the latest available scientific evidence, including improved modelling of the interaction of radiofrequency fields with the human body. It includes slightly more restrictive reference levels in some frequency ranges to ensure even larger safety margins to protect all Canadians, including newborn infants and children. The revisions to Safety Code 6 make Canada’s limits among the most rigorous science-based limits in the world. The code continues to establish a human exposure limit that is far below the threshold for potential health effects.

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To find the SAR value of your device please use the SAR Search.

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