SAR is a comparative value
that supposes to reflect how much radiation is being
absorbed into a flesh tissue when radiated by RF radiation source like a
cellphone. The units are Watt per kilogram.
The measurement is based on heating
of a water-sugar-salt based fluid inside
a dummy which is bigger than 90% of the world adult population. The radiation
source is located about 1" (2.54 cm) away from the dummy (This is way in
most mobile phone user manuals it say "keep the phone at least 1"
away from your body in all time") and is configured to transmit in max
power. The measurement last for 6 minutes (in the time SAR was invented it was
seem to be impossible that a person will use the phone for more than 6
minutes). Both temperature and RF Electric field levels are measured by a probe
that is inserted to the dummy.
The SAR is addressed as the world
wide official standard for cell-phones' radiation emission.
SAR measurement is not simple and there are only a small number of
laboratories around the world that can actually measure it. The room of the
measurement is RF and ELF shielded, and it should have no RF reflection from
the walls.
Please see the video below about SAR measurement in Australia.
Why was the SAR invented?
Officially SAR was invented to create a protocol for safety
measurement of cell-phoned. Since cell phones are held next to a person head
and brain there was a need to assess the safety of the device before putting it
on the market. There is a technical difficulty to measure RF radiation very
close to the source (in the "near field") and there was a need to
find a way to measure the levels without using RF radiation flux density. One
way of doing this is to measure at least 3 field lengths away from the source
and calculate backwards the RF radiation levels in the head and brain. The
result of this calculation showed higher levels than what is allowed by ICNIRP
so called safety standard which is based only on heat effect. So the need for a new standard that will give
KOSHER stamp to all cellphone (even if they emit very high levels of RF
radiation) appeared.
Because SAR is so difficult to understand people takes it as
granted and don't question the logic behind it.
What is wrong with the SAR?
1.
Temperature,
heat effect based standard (heat concept, don't protect from biological influences, changes and damage at none thermal levels of RF radiation).
2.
Measured
on a dummy filled with sugar-salt water.
3.
The sugar salt water is homogeneous. The brain is not, and it has more and less
condensed parts and different tissues. Test has shown that there are hot spots
in the brain where the SAR levels are about 10 times more than the measured SAR
on a dummy.
4.
The
dummy size and shape is of a big grownup. Childrens' heads are much smaller
and the radiation penetration to the head is higher. The SAR does not cover
children and small adults.
5.
The
Dummy is made out of plastic and does not block or reflect RF radiation as the
skull does. In a real head, hot spots are created due to the reflection of the
RF radiation from the skull.
6.
The
basic assumption in the time that the SAR was invented was that the longest possible cellphone use will less tha 6 minutes
(funny funny ha ha).
7.
In
the SAR measurement there is no expression to the ELF magnetic and electric
fields that are created around a cellphone while it transmits. Exposure to this
fields from levels of 2mG is considered to be a health risk. In GSM phones the
ELF magnetic field can go up to several hundreds of mG, but it will not
influence the SAR level.
No comments:
Post a Comment