Date post: | 27-Mar-2015 |
Category: |
Documents |
Upload: | kimberly-carter |
View: | 215 times |
Download: | 2 times |
Dr. Ally Y. SimbaTanzania Communications Regulatory
Authority
Challenges of Mobile Phone SAR Enforcement in Africa
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 2
Introduction
Many people want to know:
Are mobile phones safe?
Are base station safe?
EMF Exposure SafetyGeneral Conclusion of Expert Scientific Reviews
No credible evidence that RF exposure within Internationally accepted limits causes any adverse health effects
According to International guidelines, the only scientifically established adverse health effect of RF energy in the human body is thermal, and its safety limits are given based on Specific Absorption Rates (SARs)
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 3
SAR BasicsSpecific Absorption Rate (SAR) is the rate at which RF energy is absorbed per unit mass of a biological body
2||
tESAR [W/kg]
where are conductivity and densityof the material, respectively and Et is the total electric field in a biological body
SAR and Temperature RelationshipPennes bio-heat equation
Here T represents the temperature of the tissue in degrees Celsius, ρ is the materialdensity (kg/m3), c is the heat capacity (J/kg/oC), k is the thermal conductivity (W/m/°C), w is the perfusion by blood (mL/g/s), and Qm is the heat generated by metabolism(W/m3). The term Tcore represents the core, or arterial, temperature of the body.
14:23
SAR depends on the followingIncident field parameters - frequency, intensity, polarization source-object configuration (near- or far-field)
Characteristics of the exposed body - size, internal and external geometry electrical properties of various tissues
Ground effects and reflector effects of the objects in the field near the exposed body
Averaged SARSAR is usually averaged over a certain weight
10-g Averaged SAR
Whole Body Averaged SAR (WBA-SAR)
SAR Basics
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 5
Mobile SAR Limits Accordingto ICNIRP Guideline
Mobile phone exposure is categorise as localized exposure, i.e., only part of the body is exposed during use The safety limit of the localized exposure, according to ICNIRP is given:
Localized Exposure
General Public: 10-g averaged SAR = 2 W/kg Occupational: 10-g averaged SAR = 10 W/kg ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 6
Mobile SAR Limits Accordingto ICNIRP Guideline
– Human eye is about 10-g – Because of the lack of blood flow in the eye, there is low heat dissipation– Considered to be a part that is most affected in body
The limits were obtained based on the eye experiment
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 7
Mobile Phone SAR EnforcementMobile phone manufacturers are required to ensure that their phones comply with these objective limits for safe exposure
Manufactured phones, before put in to market they must under go a compliance test
Phone considered safe to be legally sold in the US and EU have FCC ID and EC mark in the phone case, usually below the batteryThe SAR values of mobile phones are available on the internet or you can find them on the specification sheet when you buy it
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 8
SAR Enforcement in Africa
Enforcement base on manufacturer compliance test and FCC or EU marking in the SAR the phone works fine in US, America and other country where strong legal systems exist, and illegal importation is almost impossible
However, this approach is not effective in most of the African countries
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 9
The case of Counterfeit Phone
Due to this fact, manufacturer compliance test cannot be used as an enforcement mechanism because even SAR value indicated in these phone may be also fake
The cell of counterfeit phone is growing problem in Africa
SAR Enforcement in Africa
These fake handsets are manufactured in a back office some where in Asia and make their way to Africa countries
This problem has increased public anxiety to the public on the safety of mobile phones
It should be noted here that, the SARs of counterfeit phones do not necessarily exceed the safety limits
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 10
Possible Solution The regulators should provide measured SAR of phones in the market annually
This can be done by taking sample phone in the market
Inform the public of this information through seminar, workshop and stake holder meeting and by publishing them in the website for public to access
Compare the SAR values in the phone manual and measured ones
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 11
SAR Measurements Approach I
Regulators need to build Type Approval Laboratories (TAL) with mobile phone SAR testing capabilities
This is very expensive project, you will need at least the following facilities and equipments. Most of these equipments are very expensive
- EMC Chamber- Mobile Phone Base Station Simulator- SAR Measurement System
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 12
SAR Measurements Approach I
For example; SAR testing System alone cost up to € 400,000 EU and annual cost of € 100,000 for maintenance and calibrations depending on the number of accessories
Taken from EMF Explained Series
SAR Measurements Approach I
Good news is less expensive testing system are developed.
Some of this do not required expensive industrial-sized robot like those used in the conventional system, hence less expensive
SARA – C (Index SAR, UK) iSAR system (SPEAG, Switzerland)
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 14
SAR Measurements Approach II
SAR measurements foreign laboratory
In this case the regulator will collect sample phones from the market and send them to foreign country for measurements
Although the cost for SAR measurement per phone has not been determine yet, this may be the short solution as the regulators are building long term solution of building long term capacity in equipment and human resource
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 15
The issue of mobile phone generate a lot of anxiety to public in many African Countries
In order to minimize the public anxiety, the SAR of of the mobile phone should be measured and the values made available to the general public
Conclusion
There is no short cut in the SAR measurements in Africa, Regulatory bodies should buy and install SAR Measurements Systems or outsource the exercise in foreign countries for few phones sampled in their market so that to satisfy the public
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 16
Thank you for your kind attention
contact: [email protected]
ITU Workshop on tackling climate change and SAR Measurement: Benin, July 19, 2011 17