Review of evidence

rawfrogpondUrban and Civil

Nov 16, 2013 (3 years and 7 months ago)

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1


Review of wi
-
fi safety
-

Learning and Teaching Scotland September 2009










Review of evidence

relating

to the use of Wireless Networks

w
ith particular reference to schools

and educational

establishments


September 2009


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Learning and Teaching Scotland September 2009





Wi
-
Fi

safety


The Scottish ICT Development Group asked at their June meeting that LTS should
review and update the evidence in relations to the safe use of wireless networks in
schools. This was in the light of several ‘scare stories’ in the media and where authorities
might wish to inform schools and parents of the evidence from bodies with exper
tise and
experience in this area. It should be noted that wireless networks have been used without
ill effect in schools for over 10 years now. High frequency wireless signals from
Television and Radio have covered the whole country for even longer period
s.


Organisers for this report

1

Health
-

mainly electromagnetic field emissions

2

Security

3

Speed and reliability


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Health Protection Agency

The Health Protection Ag
ency is an independent UK organisation that was set up by the
government in 2003 to protect the public from threats to their health from infectious
diseases and environmental hazards.


It does this by providing advice and information to
the general public,

to health professionals such as doctors and nurses, and to national and
local government

It is the successor to the former National Radiological Protection Board (NRPB)

The summary about Wi
-
Fi networks is at

http://www.hpa.org.uk/HPA/Topics/Radiation/UnderstandingRadiation/1199451940308

The international guidelines on electromagnetic fields (EMF) are available from

http://www.icnirp.org/documents/emfgdl.pdf

There is no UK legislation specifically requiring compliance with any EMF protection
guidelines. The Health and Safety Executive's requirements for safe working (qv) are at

http://www.hse.gov.uk/radiation/nonionising/electro.htm

The European Union's Radio and Telecommunications Terminal Equipment Directive
(1999/5/EC) extends the objectives with respect to safety requirements co
ntained in the
Low Voltage Directive (73/23/EEC) in order to apply to all apparatus, with no voltage
limit applying. The text of these directives can be obtained from

http://europa.eu.int/comm/enterprise/newapproach/standardization/harmstds/reflist.html

The HPA has made measurements of the power density of radio waves generally in and
about the offices where WLANs are deployed and these have always been
found to be
very much below the guideline levels referred to above. The situation is rather more
complicated for exposure within the first few centimetres of the transmitters, for example,
for the situation where a laptop computer is placed on someone's l
ap with its transmitting
antenna projecting on one side, or mounted inside the case. This is the situation where
exposure would be highest and there is no practical assessment that can be rapidly
performed to check levels with an installed system. Nevert
heless, given the low powers,
a problem with guideline compliance would not be expected

When a radio terminal is used close to the body, some of the radio energy penetrates into
the body and it is absorbed in the tissues. The pattern of this absorption an
d the total
amount of energy absorbed depend on parameters such as the frequency, output power,
position of use, antenna type, etc and it is not easy to predict without a detailed
investigation. The exposure is characterised by the specific absorption rat
e of energy
(SAR) in the tissues and this will generally have a spatial peak value near the surface of
the body and close to the radiating antenna

Guidelines expect SAR to be averaged over various different tissue
-
masses and time
-
periods before comparison
with the basic restrictions. The most stringent basic
restrictions for the situation where low power radio transmitters are used near to the body
are those on localised SAR in the head, which involve an averaging mass of 10g and an

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averaging time of six m
inutes. For this situation, the ICNIRP guidelines for workers
advise that SAR should not exceed 10W/kg. The ICNIRP guidelines … basic restriction
for the general public is that SAR averaged in this way should not exceed 2W/kg

HPA's conclusion

On the basis

of current evidence, the HPA does not consider there to be a problem with
the safety of WLAN. If an explicit statement that exposures are within the ICNIRP
guidelines is required, this would have to be obtained from the manufacturers; however, it
could b
e argued that this is implicit in the CE

marking

HPA current research

On 12

October 2007, the agency announced a programme of research into wireless local
area networks (WLANs) and their use

"There is no scientific evidence to date that WiFi and WLANs adve
rsely affect the health
of the general population. The signals are very low power, typically 0.1

watt
(100

milliwatts) in both the computer and the router (access point) and the results so far
show exposures are well within ICNIRP guidelines. Given this,
there is no particular
reason why schools and others should not continue to use WiFi or other wireless
networks. However there has not been extensive research into what people's exposures
actually are to this new technology and that is why we are initiati
ng this new programme
of research and analyses. We have good scientific reasons to expect the results to be re
-
assuring and we will publish our findings" (Prof Pat Troop, Chief Executive, HPA)

NB

ICNIRP is the International Commission on Non
-
Ionizing Radi
ation Protection

HPA's website (last reviewed in July 2009) says the following, in addition to repeating
some of the above



On the basis of the studies so far carried out in house, the

HPA sees no reason why
Wi
-
Fi should not continue to be used in schools
. However with any new technology
it is a sensible precautionary approach, as happened with mobile phones, to keep the
situation under ongoing review so that parents and others can have as much
reassurance as possible



There is no consistent evidence to
date that exposure to RF signals from Wi
-
Fi and
WLANs adversely affect the health of the general population



The signals from Wi
-
Fi are very low power, typically 0.1

watt (100

milliwatts) in
both the computer and the mast (or router) and resulting exposur
es should be well
within internationally
-
accepted guidelines



The frequencies used are broadly the same as those from other RF applications such
as FM radio, TV and mobile phones



Based on current knowledge, RF exposures from Wi
-
Fi are likely to be lower

than
those from mobile phones


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Learning and Teaching Scotland September 2009



On the basis of current scientific information, exposures from Wi
-
Fi equipment
satisfy international guidelines. There is no consistent evidence of health effects from
RF exposures below guideline levels and no reason why
schools and others should not
use Wi
-
Fi equipment

Results of HPA's further researches announced in October 2007

Following

the announcement by the Board of HPA

on 12 October 2007, a systematic
programme of research into WLANs and their use started at the

HP
A Radiation
Protection Division. At the start of the project, comprehensive Wi
-
Fi test facilities were
set up at the

HPA Chilton site and a review of technical standards and wireless equipment
used in UK schools was carried out

Due to the popularity of la
ptops in classrooms and the likelihood that the majority of Wi
-
Fi exposure would come from these devices because they are generally nearer to children
than the access points, it was decided that the experimental measurements would begin
with laptops transm
itting in the 2.4

GHz frequency band. A total of 15

laptops were
chosen from among the most popular models used

in the education sector in the UK

The objective of the laboratory measurements was to establish the radiation pattern (ie the
angular distribut
ion of electric field strength around each laptop) during transmission and
identify the angles at which the field was a maximum. The electric field strength at these
angles was then measured as a function of distance

The results have so far shown that, fo
r a given position, the field strength fluctuated
between 2 (and sometimes 3) distinct levels because of the existence of several
transmitting antennas within each laptop. Overall, similar radiation pattern measurements
for all 15

laptops have been observ
ed with a minimum in the direction from the front of
the laptop (towards the torso of the user). Generally, two angular maxima were observed
that were symmetrically opposed across a vertical plane bisecting the screen and
keyboard. All 15

laptops tested
had electric field strength values indicating they had
output powers during transmission in the range 6
-
20

mW. Taking into account the
directional properties, the Equivalent Isotropically Radiated Power (EIRP) calculated for
all laptops was in the range 17
-
57

mW and well below the 100 mW (EIRP) limit set for
Europe

These results are consistent with the HPA position that exposures to the radio waves from
Wi
-
Fi equipment are not expected to exceed internationally
-
accepted guidelines and that
they are less tha
n from mobile phones. Further results will be published on the

HPA
website after they have been finalised

Further work

The remainder of the laboratory measurements includes the assessment of the electric
field strength around access points operating at 2.
4 GHz. Measurements will also be
carried out on a selection of laptops and access points operating in the 5 GHz band


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Further work will then involve the modelling of Wi
-
Fi equipment and its internal RF
structures (antennas) in order to assess the localised

specific energy absorption rates
(SARs) in users, including children. In addition, measurements of radiated powers and
transmit time proportions in schools are planned

The experimental results, together with information from other studies on radio signal
s
and health, will then be used as the basis for a wider health risk review

Some of the preliminary results were reported in a June 2009 paper to the
European
BioElectromagnetics Association
conference in Davos [
http://bioem2009.org/session
-
9
],
from which the following is a selection

"People using wireless computer networks (Wi
-
Fi), or in proximity to the equipment,
are exposed to the radio signals and will absorb some of the transmitted energy in their
bodies
. The output power of Wi
-
Fi equipment is restricted to a maximum of 100 mW
at 2.4 GHz in Europe, and there is no expectation that exposures will exceed
international guideline levels. Nevertheless, this rapidly developing technology is
increasingly used
in schools and, given the existing precautionary advice in many
countries to discourage non
-
essential use of mobile phones by children

…, it is
important to quantify the exposure from Wi
-
Fi equipment, as used by children in
schools"

"Discussions and inform
ation gathered at the start of the project showed that laptops are
the most popular wireless devices used in schools, with IEEE 802.11g as the most
widely utilised standard. For this work, a total of 14

laptops were chosen from among
the most popular mode
ls used by the education sector in UK. The objective of the
laboratory measurements was to establish the radiation pattern (ie angular distribution
of electric field strength around each laptop) and identify the angles at which the field
is maximum. The
electric field strength at these angles was then measured as a
function of distance. The measurements were carried out within an anechoic chamber
(3.7m x 2.4m x 2.4m), lined internally with radiofrequency absorber material, and with
a purpose built manual

positioning system. Dedicated software (LanTraffic) was used
to generate and monitor the Wi
-
Fi signal from the laptops set to transmit at roughly
22

Mbps, the maximum sustained rate that could be reliably maintained using the IEEE
802.11g standard. The
screen of the laptops was opened to an angle of 115

degrees for
this work"

"An Agilent N9020A MXA signal analyser was used which has a bandwidth of 25

MHz
allowing the detection of the whole WLAN signal. This instrument captures individual
Wi
-
Fi bursts in

the time domain and demodulates them to identify the burst power,
modulation scheme and many other parameters. For this work, the power of 50

bursts
was measured at each position and then analysed in terms of the statistical distribution.
To establish t
he radiation pattern, the E
-
field strength at 1m distance from the laptop
was measured by an ARC Seibersdorf miniature biconical antenna in horizontal and
vertical polarisations for azimuth and elevation rotations in 30

steps for the laptop on

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the manual p
ositioning system (168

positions in total). The measured E
-
field data were
then analysed and the angles of maximum radiation were identified. The manual
positioning system was then set up at these maximum angles and the E
-
field strength
was measured in 1
0cm steps from 0.5m to 1.9m for each laptop"

Results

"Burst power measurements drifted by 15% in the first 30

minutes after switch
-
on as
opposed to less than 3% after 2

hours of transmitting, emphasising the need for
adequate equipment warm
-
up times. Furt
hermore the results showed that, for a given
position, the power level fluctuated between 2 (and sometimes 3) distinct levels
because of the use of switched diversity with several antennas within each laptop.
Overall, the results showed similar radiation
pattern measurements for all laptops, with
a minimum in the direction of the front of the laptop (torso of the user). Generally, two
angular maxima were observed that were symmetrically opposed across a vertical
plane bisecting the screen and keyboard. T
he laptops had antennas mounted on the top
left and top right corner behind their screens and each of these antennas would have
been responsible for producing one of the maxima. The maximum E
-
field recorded at
1m varied from (719±14)

mVm
-
1

to (1306±3)

mVm
-
1
. In terms of power density, all
these values are well below the level that would be expected based on the 100 mW
(EIRP) limit, as shown in Figure 1"


Figure 1. The calculated power density for all 14

measured laptops. The
error bar represents the repe
atability of E
-
field measurements for 50

samples
(only the highest observed variation is presented)

Health and sustainable homes and communities conference: September 2009

Some of the findings of their research were outlined in more detail at Health Protec
tion
2009 at the University of Warwick in September 2009

The slides presented by Simon Mann, one of the researchers involved in the project can
be seen at

http://www
.hpa
-
events.org.uk/HPA/media/uploaded/EVHPA/event_74/Mann_14.pdf

The conclusions from the research as summarised as follows

"Emitted powers were very low for the 15

laptops

"



Integrated (total) radiated powers ranged from 6 to 19 mW


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"



Effective powers

ranged from 17 to 57 mW in the direction of maximum emission
(within the regulatory maximum of 100 mW)

"Results consistent with HPA's present position that exposures are

"



well within exposure guidelines and

"



less than from mobile phones"

In the seco
nd phase of the research project, HPA is looking into the following

"Measurements of the EMF strengths around the selected devices during transmission
and calculations of radiated powers (including wireless access points)

"Measurements of the proportion of

the time that individual Wi
-
Fi computers transmit
during typical school lessons

"Computer modelling of energy absorption in the body when using Wi
-
Fi equipment
under various scenarios

"Health risk review drawing on the exposure measurements and modelling"


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Health and Safety Executive

Source =
http://www.hse.gov.uk/radiation/nonionising/electro.htm

A directive (April 2008) to postpone, for four years, until 30 April 2012, the deadline
for
introducing legislation on workers' exposure to electromagnetic fields has now been
adopted by the European Union (EU)

The Directive puts on a legal footing internationally accepted (ICNIRP) guidelines which
are designed to protect people from the acut
e effects of exposure. The ICNIRP EMF
guidelines are almost identical to those published by the former National Radiological
Protection Board (now incorporated into the Health Protection Agency) that are currently
used both by industry and HSE Inspectors
when assessing risk from exposure to
electromagnetic fields

ICNIRP is a body of independent scientific experts whose principal aim is to disseminate
information and advice on the potential health hazard of exposure to non
-
ionising
radiation including elect
romagnetic fields. Their guidelines on exposure to EMFs have
been developed as a result of an extensive process of expert review of the scientific
literature and consultation with other experts and professional bodies


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JANET

JANET is the UK's education and

research network, Their 2007 factsheet entitled
'Wireless networks: health and safety issues and recommendations' includes the following
statements [
http:/
/www.ja.net/documents/publications/factsheets/056
-
wireless
-
health
-
safety.pdf
]

"In general, according to the Health Protection Agency and the Wi
-
Fi® Alliance,
wireless LAN (WLAN) networks do not appear to provide a cause for concern
regarding health when p
roperly handled"

"The Health Protection Agency has published results on WLAN measurements within
the office environment. Power densities were found to be much lower than their
guideline levels. The Health Protection Agency comments that levels would be hig
her
the closer you are to the device, such as a laptop on the knees, where distances may be
a few centimetres. However, it considers that the transmitters are of low power and
unlikely to provide a problem in terms of compliance with the guidelines"

"The W
i
-
Fi Alliance, as one would expect, is sensitive to WLAN health and safety
issues, and states that: 'Manufacturers of Wireless Networking products design their
products to operate within the guidelines of [these] standards and recommendations
and, therefor
e, are considered safe.' In this light, along with the Health Protection
Agency statement, it would seem wise to purchase equipment which has the
appropriate markings


CE with regard to any applicable European legislation, and Wi
-
Fi, for the Wi
-
Fi Allianc
e"

Their recommendations for use are as follows

"All the authorities consulted agree that normal use of wireless networking equipment
does not expose the user to harmful levels of radiation. However, to further reduce the
level of radiation experienced, th
e following practical steps may be considered:

"•

The location of all wireless network installations must be registered and published
by the institution in an area where it can be readily consulted by the user
community. Signage also could assist in identi
fying wireless areas. For such areas,
the potential for microwave
-
induced auditory effects should be noted, and
avoidance recommended. The potential effect on prosthetic devices must be noted
and users pointed towards consultation with manufacturers and/or

health authorities
on their particular case

"•

Purchase CE
-

and Wi
-
Fi marked equipment and follow manufacturer's instructions
for installation and operation. Proper operation and installation of access points and
PC cards is required to reduce exposure to

below recommended guideline limits

"•

Do not touch or move antenna(s) while units are transmitting or receiving. Do not
hold any component containing a transmitting radio such that the antenna is very
close to or touching any exposed parts of the body, es
pecially face or eyes. In
particular for open areas, the proximity of transmitters must be considered (for

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example, touching is to be avoided). This may be very relevant in informal areas of
use where crowding may be common (cafeteria, etc.). The considera
te and careful
location of PC aerials must be noted. For an antenna user, always orient the antenna
so that it is at least 20cm away from the body"


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CENELEC, ICNIRP and SSERC

CENELEC

(Comité Européen de Normalisation Électronique) is, in English, the
Europ
ean Committee for Electrotechnical Standardization. It is responsible for European
standardisation in the area of electrical engineering. Although not a European Union
agency, it performs this function for all the EU and EEA members

Specific absorption r
ate (SAR) is a measure of the rate at which energy is absorbed by the
body when exposed to a radio frequency (RF) electromagnetic field. It is defined as the
power absorbed per mass of tissue and has units of watts per kilogram. SAR is usually
averaged e
ither over the whole body, or over a small sample volume (typically 1g or 10g
of tissue). The value cited is then the maximum level measured in the body part studied
over the stated volume or mass

CENELEC specify SAR limits within the European Union (and
more widely). For
mobile phones, and other such hand
-
held devices, the SAR limit is 2W/kg averaged over
10g of tissue

Guidance from
ICNIRP

(International Commission on Non
-
Ionizing Radiation
Protection) relates to SAR limits [
http://www.icnirp.de/documents/emfgdl.pdf
]

In tissue, SAR is proportional to the square of the internal electric field strength. Average
SAR and SAR distribution can be computed or estimated from laboratory measurements.
Va
lues of SAR depend on the following factors



the incident field parameters, ie the frequency, intensity, polarization, and source
-
object configuration (near
-

or far
-
field)



the characteristics of the exposed body, ie its size and internal and external ge
ometry,
and the dielectric properties of the various tissues



ground effects and reflector effects of other objects in the field near the exposed body

ICNIRP basic restrictions for time varying and magnetic fields for frequencies in the
range 10MHz to 10G
Hz (which covers all the currently used wireless networks) suggest
the following limits for SAR (measured as watts per kilogram) for general public
exposure; occupational levels are 5

times higher in each case [table

4 on page

16]

Whole body average SAR

0.
08

Localised SAR (head and trunk)

2.00

Localised SAR (limbs)

4.00

SSERC

guidance states

"If the output power of a WLAN system is less than 20mW, the exposure of a person
cannot exceed the ICNIRP guidelines under any condition. This is because, even if the

system was able to somehow deposit its full output power into a 10g mass of tissue, the
SAR averaged over this tissue mass would not exceed 2W

kg
-
1
, which is the most

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stringent basic restriction on localized SAR recommended by ICNIRP for members of
the pu
blic

"It is a condition of EN

300

328 that the effective isotropic radiated power (EIRP)
emitted from a WLAN is less than 100mW"

"Only one transmitter in a network is active at any time. The radiated power of a total
network with lots of computers will no
t exceed the radiated power of a single computer

"WLAN transmits data in bursts. If a user transfers 100

megabytes of data in a day,
then a typical WLAN transmitter would be broadcasting for about 10

minutes in that
day"

Survey of schools in East Lothian

In September 2001 a joint investigation between NRPB [since subsumed into the Health
Protection Agency] and SSERC was carried out in 2

schools in East Lothian fitted with
wireless local area networks (WLANs) using Apple AirPort. The scope of the
investiga
tion was



Examining the WLAN installations



Measuring radio wave strengths and commenting on people's exposure in relation to
accepted safety guidelines

Hand
-
held surveying probe

A probe with a thermal sensor was held in various locations in close proxim
ity to base
stations and computer terminals. The probe's sensitivity threshold was around 0.5W m
-
2
.
This is 20

times lower that the ICNIRP public reference level of 10W

m
-
2

(2.4 ~2.5
GHz). The probe gave no reading in any location. It may be inferred
that compliance
with guidelines is assured for distances greater than 10cm from the WLAN transmitting
antennae surveyed. (The probe is unreliable at lesser distances because the overall size of
its sensor is around 5cm)

Spectral monitoring surveys

The pow
er density and frequency of radio signals were measured at two sites in one
school and in one site at a second school. The measuring equipment comprised calibrated
antennae and a spectrum analyser. Radio signals within the WLAN system were detected
with
a ridgeguide horn antenna. Signals from broadcast radio and mobile phone base
stations were picked up with a biconical antenna and log periodic antenna respectively

Results from one of the primary schools in detail

The survey site was the centre of a firs
t (and top) floor classroom in a stone
-
built
building. A nearby base station was sited at a height of 2.5m in an adjacent corridor. RF
radiation travelled indirectly into the room by multiple reflections off walls and
transmission through windows sited i
n the wall between the corridor and classroom.
Because of the receiver's situation, radio signals from the wireless LAN were relatively
weak whereas those from remote transmitters were quite strong


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[This shows that, although operating at different freq
uencies, the power density of the
wireless network or WLAN (blue triangle) is about the same as FM radio (green square)
and UHF television (purple diamond)]


[This shows that of all the electromagnetic emissions measured in the classroom and
which totalle
d just over a four thousandth of the ICNIRP level for public exposure
(0.027%), only 0.018% came from the wireless network within the classroom]

Preliminary summary of NRPB investigation

Wireless LAN transmitters use very low total radiated powers
-

tens o
f milliwatts

Radio signal strengths range greatly inside schools

The WLAN signals are comparable in strength to those from distant transmitters

Exposures at the locations surveyed were very much below guideline levels


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Some comparators

Typical microwave ov
en gives off 100,000 times the ionising radiation intensity of a wi
-
fi
network

The Health Protection Agency points out that a person sitting in a wi
-
fi hotspot for a year
would be exposed to only the same amount of radiation from a 20
-
minute mobile phone
c
all (BBC news report, 21

May 2007)

FM radio and TV signals are about the same strength as wi
-
fi

The radiation levels that we are exposed to by Wi
-
Fi equipment, including WiFi in laptop
computers, can be lower than the radiation that leaks out of some domes
tic microwave
ovens (Lever Technology Group)


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Security

It is often argued that wireless networks are inherently less secure than wired networks.
While this is not necessarily so
-

VPNs, encryption and other approaches can make
wireless completely secure
-

there are some inherent dangers to wireless operation 'out of
the box'

Evil twin attack

This is where a stronger signal in a classroom or Wi
-
Fi hotspot captures
attention and potentially feeds useful personal data to a malefactor. But it is usually
poss
ible to ensure that only prescribed networks are joined within a school environment

Outsiders piggy
-
backing on to a wireless network
-

free riders

Such squatters use up
bandwidth. There may also be a small danger of grooming by those who, in a former age
,
would hang around the gates of schools. One solution is to implement MAC address
filtering to ensure that only authorised network devices (wired as well as wireless) can get
access through the wireless access points

Sniffer programs to detect network tr
affic

While this is possible, it is hard to believe that
anyone would regard a school as a worthwhile source of useful traffic. This might
capture individual log
-
in details, which could be used later to create mayhem, or what
some of the young people mig
ht characterise as "just some fun". If the log
-
in details are
for staff, there is potential for more serious interference with school records (attainments
or other). Wireless encryption, using the older WEP (apparently compromised by some
dedicated hacke
rs) or the newer WiFi Protected Access (WPA) should encrypt all traffic,
including log
-
in

The traffic within a school is seldom sensitive. No
-
one should be using wireless (or
wired) networks to make personal purchases using credit cards. The only area wh
ere
there may be a degree of sensitivity is in the transmission of assessment materials (eg
examination papers in draft or final form, test results), where there is some scope for
dedicated hackers to cause embarrassment or uncertainty about the validity o
f particular
examinations


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Operations

The following issues can be discerned

1

Speed

In comparison with wired networks, wireless networks are slow
-

see
http://www.ja.ne
t/documents/publications/factsheets/055
-
wireless802.pdf

for a
summary of the nominal and planned speeds which can be achieved through
IEEE

802.11 standards (May 2007)

The IEEE

802.11g standards offers only 20mbps shared between users; unless there is
a si
ngle user (teacher), this will not easily cope with streaming video or downloads of
rich media files. Variations in signal strength also mean that there can be 'dead zones';
building materials and other networks (qv) can also interfere with signal strengt
h.
Limits to the range of wireless networks, especially coupled with building and
electrical wiring interference, mean that some areas of schools (eg games halls) often
are less well served than mainstream classrooms in the core of the building

2

Interfer
ence with the wireless network

The following are known to generate problems: microwaves, Bluetooth; passive
infrared detectors. There are other devices which also operate in the crowded 2.4GHh
industrial, scientific and medical band. Other electromagnet
ic devices, including
speakers or lift motors, can provide occasional interruptions to smooth delivery

3

Interference by the network devices

There is a theoretical possibility of interference by transmitters and antennae with
medical devices such as prosth
etic devices, cochlear implants, pacemakers
-

see
http://www.mhra.gov.uk/Safetyinformation/Generalsaf
etyinformationandadvice/Techni
calinformation/Mobilecommunicationsinterference/CON019620

The Medicines and Healthcare products Regulatory Agency (MHRA) is the
government agency which is responsible for ensuring that medicines and medical
devices work, and
are acceptably safe. Their recommendation is that low power
computer wireless networks represent a very low risk and so "These systems are very
unlikely to cause interference under most circumstances and need not be restricted"

4

Microwave induced auditor
y response

This may be a problem for a very small number; this may be linked with the condition
sometimes labelled 'electrosensitivity'; individual sufferers should not be sited near the
sources of microwave transmitters and antennae

Conclusion

Wireless ne
tworks may be seen to be helpful in the following contexts



The ability to turn any classroom temporarily into a 'computer room'



Supplementing a wired backbone


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-
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-

Learning and Teaching Scotland September 2009



Ensuring that school buildings which have asbestos issues or limited future life (eg
reloca
tion, subject to consultation about closure or amalgamation) can nonetheless
enjoy the same entitlements as those who occupy modern buildings, without asbestos
or threats of closure and with recently installed flood wiring

It may also be seen as helpful in

preparing teachers, managers and the young people
themselves for a wholly different paradigm where hand
-
held (mobile telephone derived)
devices will become a commonplace feature of learning. To date the computer may be
seen as a supplement or occasionall
y alternative to the book. The next stage is for
learning technologies to represent a supplement or alternative to the jotter or slate (for
older readers like this consultant)

It is inconceivable that this sort of interactivity can be done within a wired
environment.
The health and safety fears alone
-

tripping over wires, electromagnetic emissions
-

would
cause understandable alarm




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Scare stories

From
The Times
, December 2006

[
http://www.timesonline.co.uk/tol/life_and_style/health/features/article665419.ece
]

"David Dean, 43, a councillor in Merton, South London, and the managing director of a
publishing company, describes himself as a human antenna. 'The m
oment I go into
people's houses I know whether they have wi
-
fi because my head starts to buzz. I had
to leave my last job because I couldn't stand up for more than ten minutes in the office
and my boss would not remove the wi
-
fi. My heart raced, I had doub
le vision and
really bad headaches. It felt as though my head was in an arm lock. Twice I have been
into homes where the children were screaming monsters. After I suggested to the
parents that they turn off the network for two days, the kids were transform
ed'."

"One of the problems in conducting research is that not everybody is affected by
electromagnetic radiation in the same way. 'A growing, consistent body of literature
demonstrates that a subgroup of the population appears to suffer distressing symptom
s
when exposed to this type of radiation,' says Dr Elizabeth Cullen, of IDEA. Sleep
disturbances, depression, blurred vision, heart and breathing problems, nausea and
headache are among the most common symptoms. Up to 5 per cent of the population
is thou
ght to have this sensitivity, which is recognised in Sweden as a disability. In
Stockholm sufferers can have their homes adapted to remove or screen out sources of
electromagnetic radiation. If this proves ineffective, they can even rent council
-
owned
cott
ages in areas of low radiation"

"A literature review conducted by the International Commission for Non
-
Ionising
Radiation Protection concluded: 'Results of epidemiologic studies to date give no
consistent or convincing evidence of a causal relation between

exposure from radio
frequency fields (RFs) and any adverse health effect. On the other hand, these studies
have too many deficiencies to rule out an association. Despite the ubiquity of new
technologies using radio frequency fields, little is known abou
t population exposure
from RF sources, and even less about the relative importance of different sources'."

Following the Panorama programme on WiFi in schools on Monday 21

May 2007

[
http://www.ce
llular
-
news.com/story/29482.php
]

[
http://www.badscience.net/2007/11/bbc
-
editorial
-
complaints
-
unit
-
debags
-
the
-
panorama
-
wifi
-
scare/
]

[
http://www.mobilecomputermag.co.uk/20071204193/bbc
-
wi
-
fi
-
safety
-
complaints
-
upheld.html
]

"The BBC's internal Editorial Complaints Unit has upheld a complaint about

a TV
documentary, Panorama which was shown on UK television last May and called into
question the safety of Wi
-
Fi radio signals. During the program, Dr Gerd Oberfeld, from

20


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-
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-

Learning and Teaching Scotland September 2009

Salzburg called for Wi
-
Fi to be removed from schools, and this sparked a wave of
sc
hools in the UK clamping down on Wi
-
Fi usage

"However, the program was found to have given an unbalanced impression of the state
of scientific opinion on the issue

"The programme reflected concerns about Wi
-
Fi which had been expressed by Sir
William Stewar
t, Chairman of the Health Protection Agency, and the BBC's
complaints unit said that it was legitimate to focus on questions raised by an eminent
scientist with particular responsibility for public health issues. The programme made
clear that its measureme
nts of Wi
-
Fi and mobile phone mast radiation were taken at the
points where schoolchildren were likely to be exposed to the respective signals, thus
avoiding the false impression that the level of radiation from Wi
-
Fi was higher at
source, and the results
to date of the experiment on "electro
-
sensitivity" were correctly
represented as inconclusive

"However, the programme included only one contributor (Prof Repacholi) who
disagreed with Sir William, compared with three scientists and a number of other
speake
rs (one of whom was introduced as a former cancer specialist) who seconded his
concerns

"This gave a misleading impression of the state of scientific opinion on the issue. In
addition, Prof Repacholi's contribution was presented in a context which suggeste
d to
viewers that his scientific independence was in question, whereas the other scientists
were presented uncritically. This reinforced the misleading impression, and was unfair
to Prof Repacholi"

From
Daily Telegraph
, 23

July 2007

[
http://www.telegraph.co.uk/news/worldnews/1558277/Commissions
-
fears
-
over
-
wi
-
fi
-
safety.html
]

"In April The Daily Telegraph revealed that Prof Lawrie Challis, a leading exp
ert on
mobile phone emissions, had called for pupils to be monitored because of high levels
of radiation from wireless internet networks in schools

"Sir William Stewart, the chairman of the Health Protection Agency (HPA), then called
for a review on the is
sue after emissions from one school's wi
-
fi network were shown
to be three times those from a nearby mobile phone mast"

From
Dance with Shadows

blogging network, 30

April 2007

[
http://www.dancewithshadows.com/tech/wireless
-
laptop
-
safety.asp
]

"However, if the user places a laptop straight on his lap and uses using wi
-
fi, he could
be around 2 centimetres from the transmitter, and receiving almost the same amount of
exposure from
a mobile phone

"Children are much more sensitive than adults to a number of other dangers, such as
pollutants like lead and ultra
-
violet radiation. So if there should be a problem with

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Learning and Teaching Scotland September 2009

mobile phones, then it may be a bigger problem for children, Prof Chall
is said. Since
we advise that children should be discouraged from using mobile phones, we should
also discourage children from placing their laptop on their lap when they are using wi
-
fi"

Lakehead University in Ontario, Canada, reported in
The Register

[
http://www.theregister.co.uk/2006/02/22/canada_uni_wifi_ban/
]

"Fred Gilbert, president of Canada's Lakehead University, made the order on the basis
of possible health risk from the

technology, especially to young people. Inconclusive
studies into possible links between radio transmissions and leukemia and brain tumors
from, among others, scientists for the California Public Utilities Commission, led
Gilbert to make the "precautiona
ry ban"

"'All I'm saying is while the jury's out on this one, I'm not going to put in place what is
potential chronic exposure for our students. Admittedly that's highest around the
locations of the antenna sites and the wireless hot spots, but those are
the places people
tend to gravitate to because they get the best reception,' Gilbert said, Canadian
technology website IT Business reports"

Electrosensitivity

[
http://www.badscience.net/2007/06/bmj
-
column
-
why
-
dont
-
journalists
-
mention
-
the
-
data
]

"For two years now the British news media has been promoting the existence of a new
medical condition, called electrosensitivity, or electromagnetic hypersensitivity.
The
story
-

or in medical terms the hypothesis
-

is that a wide range of symptoms are caused
by acute exposure to electromagnetic signals, and that these symptoms are ameliorated
by this signal being removed"

"If these symptoms were caused by electromagnet
ic signals, then it should prove
possible to study that, ideally in double blind conditions: and yet the media coverage
invariably focuses on the scandal of how research into this area has been neglected. But
the research has been done"

"There have now bee
n 37

such double blind 'provocation studies' published in the peer
reviewed academic literature, and they are almost all negative, although you could
argue that the evidence is unanimous. There are, to be clear, seven studies that did find
some statistica
lly significant effect for electromagnetic signals: but for two of those,
even the original authors have been unable to replicate the results; for the next three,
the results seem to be statistical artefacts; and for the final two, the positive results are

mutually inconsistent (one shows worsened mood with provocation, and the other
shows improved mood: still sure a one tailed t
-
test is reasonable?)"