Safety in rf

Safety in Radio Frequency
(RF)

Section Content
1. Introduction
1.1 Purpose of Document
1.2 References
1.3 Applicability of the Policy
1.4 Definitions
2. General RF Inform ation
2.1 RF overview
2.2 Base Station Antennae
2.3 Microwave Links
2.4 General Health Effects
2.5 Employees and Contractors Special Health Considerations
3. Responsibilities
3.1 General Information
3.2 Employer Responsibilities
3.3 Managers and Supervisors Responsibilities
3.4 Risk Assessments
3.5 Employee Responsibilities
4. RF Field Strength Measu rem ent
4.1 Personal Monitors
4.2 Area Monitors
4.3 Survey Instruments
4.4 RF Alarms
4.5 Potential or Suspected RF Exposure
4.6 Summary
5 UK and International Standard s

6 Safe Systems of Work
6.1 Risk assessment – Undocumented/Unregistered RF Levels
6.2 Risk assessment – Documented RF Levels
6.3 Control of Risks
6.4 Management
6.6 Exclusion Zones
6.7 Transmitters
6.8 Feeders
Appendix A Basic Exposure Restrictions
Appendix B Antennae Types and Exclusion Zones
Appendix C Example of an RF Permit to Work
Appendix D Training Courses

1. Introduction
1.1 Purpose of Document
The purpose of this document is to define and explain the practical requirements for ensuring
that suitable and sufficient safe systems of work and standards are utilised for all work
where there is the potential or actual likelihood for exposure to radio frequency (RF) energy
whilst working on behalf of the Company or any Client.
This Policy outlines GTL’s approach to the managing of safety issues which arise when
supporting Client’s network operations and to other radio systems encountered during
GTL activities at telecommunications sites shared with other Operators.
1.2 References
i) Health and Safety at Work etc Act 1974
ii) Restrictions on Exposure to Static and Time Varying Electromagnetic Fields
and Radiation - NRPB-GS11
iii) Restrictions on Human Exposure to Static and Time Varying Electromagnetic Fields
and Radiation - NRPB
iv) ICNIRP Guidelines for limiting Exposure to Time-varying Electric, Magnetic and
Electromagnetic Fields (up to 300GHz) - NRPB
v) ICNIRP Guidelines for limiting exposure to time-varying electric, magnetic
and electromagnetic fields (up to 300 GHz)
vi) RF and Microwave Radiation Safety Handbook - Ronald Kitchen
1.3 Applicability of the Policy
This Policy is applicable to the significant energy levels emitted from RF
transmitting equipment found at telecommunications sites and encompasses the full
spectrum of frequencies.
GTL supports Clients operating mobile communication networks which deploy radio signals to
provide: -
ii) coverage to geographic areas from Base Station antennae
iii) connections to the wider communications network via microwave transmission links
The safe systems of work and the associated safety standards detailed in this Policy apply to
GTL employees, contractors and subcontractors who perform work on, or in the vicinity of
RF equipment. Additionally, this Policy applies to other parties carrying out work at Client
locations where they either do not have their own standards and safe systems of work or
they are to a lower standard than specified within this Policy. In either instance, the GTL
Policy must be adhered to by all individuals who perform activities or tasks on behalf of GTL.

1.4 Definitions
i) “An antenna” is a composite structure of elements which are individually designed to
emit, absorb or reflect electromagnetic waves and their purpose is either: –
a) to transmit RF energy into free space and to concentrate it in particular
directions
Or
b) To receive RF energy from free space and amplify the signals to a usable level.
ii) “Competence” is having the necessary ability through qualifications, training,
experience and technical knowledge to work appropriately and to a standard that when
an unacceptable level of harm is realised, the appropriate actions are taken which may
include seeking advice and subsequently ceasing to work.
iii) “Hazard” is something with the potential to cause harm
iv) “Electromagnetic waves” are emissions from an energy source which has electrical
and magnetic components fluctuating sinusoidal at a distinctive frequency
v) “An exclusion zone” is an area around an antenna in which the RF field strength
may exceed safe limits for human exposure and no one may enter whilst the
antenna is transmitting.
vi) “Feeder” is the physical connection between a transmitter and an antenna which can be
a waveguide, a coaxial cable or a simple electrical conductor.
vii) “Field strength” is the intensity of the electromagnetic energy at a particular location and
can be expressed as a power density or in terms of electrical or magnetic pressure.
viii) “Ionising” means an energy level and frequency that is capable of damaging the
cell structure of living tissue at a molecular level as it changes the balance of
charged particles.
ix) “Leakage” is where RF energy escapes from an antenna, feeder or transmitter in an
unintended manner.
x) “Non-ionising” means the inability to change the balance of charged particles in
the molecular structure of living tissue.
xi) “Radio frequency (RF)” is the frequency band for electromagnetic waves between 3
KHz and 300GHz.
xii) “Reference level” is the lowest intensity of an RF field at which there could be a
hazards to humans.
xiii) “Transmitter (Source)” is a device for converting electrical power to RF energy.

2.0 General RF Information
2.1 RF overview
RF transmissions consist of electrical and magnetic waves emitted as electro-magnetic energy
from a power source via an antenna that concentrates the energy in to a beam or radiation
pattern of a particular shape. The result is a field with electrical and magnetic components
and this field varies according to the distance from the antenna and the position in its
radiation pattern. There are numerous antenna types and it is not apparent from their
appearance whether the field emitted by them represents a safety hazard.
The spectrum of electromagnetic emissions
Frequency Examples of typical applications Wavelength Band
300 to 3000GHz Lasers 1 mm to 0.1 mm Light
30 to 300GHz Military radar / Radio astronomy / 1 cm to 1 mm EHF
Short link microwave pt to pt
3 to 30GHz Satellite comms. / Radar / 10 cm to 1 cm SHF
Microwave pt to pt
0.3 to 3GHz TV / Paging / Cell phones 1 m to 10 cm UHF
30 to 300MHz FM radio / VHF / TV / 10 m to 1 m VHF
Emergency services mobile radio
3 to 30MHz HF radio / CB radio 100 m to 10 m HF
0.3 to 3MHz AM radio / Radio navigation / 1 km to 100 m MF
Ship to shore radio
30 to 300KHz LF broadcast and long range 10 km to 1 km LF
communications radio
3 to 30KHz Navigation beacons 100 km to 10 km VLF
0 to 3KHz AC power transmission over 100 km ELF
2.2 Base Station Antennae
Base station antennae operated within mobile communications networks in the UK are
installed in compliance with an international safety standard which has been established
by the International Commission on Non-Ionising Radiation Protection (ICNIRP). Antenna
installations are designed and installed to ensure that individuals are not exposed to radio
signals of strengths in excess of the ICNIRP public exposure guidelines.
Base station radio signals rapidly decrease in power as they leave the antennae since the
antennae’ function is to dissipate radio signals throughout the base station coverage area.
Subsequently, the radio signals transmitted from Client’s base station antennae only exceed
the ICNIRP public exposure guideline within a small area and very close to the antenna. This
small area is known as the antenna exclusion zone.
GTL’s Clients should be installing base station antennae which are “safe by design” and in
compliance with the ICNIRP guidelines, with the majority being installed such that it is not
possible to enter the antenna exclusion zone. One method which may be adopted is to
mount the antennae on poles, stub towers or on the faces of buildings so that the exclusion
zone occurs in free space.

On the very rare occasions where an antenna exclusion zone occurs within an accessible
area, then the Clients should have installed barriers thus precluding uncontrolled access
within the exclusion zone.
2.3 Microwave Links
The radio signals transmitted from radio links operated by Clients should not exceed
ICNIRP levels and therefore no safety-based exclusion zone would be mounted around
these specialist antennae.
2.4 General Health Effects
RF transmissions are classed as non-ionising radiation and cause cell damage or changes in
cell function only through a heating effect caused by the absorption of electromagnetic
energy. This is most pronounced and most hazardous when the wavelength corresponds with
the physical dimensions of the human body structure as it produces a resonance effect.
Standards of exposure take into account the facts above and reduce the reference level of
the field strength at wavelengths over a range spanning these dimensions.
Ill-health effects resulting from over-exposure are usually the result of cumulative damage to
sensitive tissue. For example, the formation of cataracts is a well-known result of the
absorption of high levels of RF energy in the eye. Exposure to high power fields produced by
broadcast transmitters, radar and tropospheric scatter installations can cause heating of
internal organs which could be fatal if prolonged.
The process is always subtle as tissue damage precedes any physical awareness.
2.5 Employees and Contractors Special Health Considerations
Employees with implanted heart pacemakers, insulin pumps or passive metal plates such as
those used to repair broken bones should seek the advice of their medical consultant or
surgeon prior to accessing areas where antennae are installed or work on any element of an
RF transmitting system.
The normal function of the active implants can be disrupted by certain patterns of RF
transmission but unpleasant effects may be experienced when passive implants are
subjected to an RF field.
Individuals needing to gain access to areas containing RF antennae will have been required to
have undergone a medical assessment which must have been “passed” and any of the above
medical conditions highlighted and advised on, as part of their appropriate climber training
(e.g. roof top, occasional climber etc).

3. Responsibilities
3.1 General Information
The following information will aid managing the risks from exposure to RF fields: -
i) RF fields at typical transmitting sites may be complex, particularly where they are made
up of components from a variety of power sources. Measurements of field strength at
multi-user sites using suitable measuring equipment may be the only way to assess the
associated RF risk.
ii) As it is not possible to provide personal protection against the absorption of
electromagnetic energy then RF hazards need to be controlled where reference levels are
exceeded. The control should initially be by the elimination of the RF field and if this is
not feasible then by the reduction of the RF field and finally by the establishment of
antenna exclusion zone (ref. the section on “Safe Systems of Work”)
iii) There may be some instances where work within an exclusion zone is unavoidable and as
such arrangements MUST be made firstly for the antenna to be powered down, however
where this is not feasible, then for its field strength to be reduced below the reference
level. Safe working conditions must be secured by locking or guarding the associated
power controls and by continuous monitoring of field strength whilst work is in progress.
Where work is performed in areas which have been assessed and identified as presenting
an RF hazard, work may only be carried out by or under the supervision of a competent
person.
Competence for specific tasks or for generic activities must be endorsed by the manager
directly responsible for the work.
iv) Safety information, instruction and training must be provided to employees required to
operate in work locations where a risk assessment has identified an exposure to RF fields.
3.2 Employer Responsibilities
GTL is legally required to take all reasonable steps to ensure the safety of its employees and
others who may be at risk as a direct result of the activities of the Company and its agents.
The key elements of this responsibility comprise: -
i) the assessment of risk
ii) the design of safe systems of work
iii) the provision of training for employees on the safe systems of work
iv) the provision of measurement equipment when required to monitor RF field strengths
v) Appropriate management arrangements to ensure supervision and compliance to
the safe systems of work by employees and contractors under their control.
3.3 Managers and Supervisors Responsibilities
Managers and supervisors must arrange for employees, contractors and third parties working
at GTL Client sites with RF hazards to be provided with appropriate information to allow them
to understand the risks and the safe systems of work that the Company has introduced for
their protection.
Managers and supervisors must be aware of the special health considerations for
employees with surgical implants (refer to 2. v) and must supervise employees and others
under their control to ensure that they are adequately protected against RF hazards.

Site records should be owned by those in control of the transmitter, to enable the provision
of information on RF hazards to other parties who may be exposed to risk at these sites.
3.4 Risk Assessments
In order to ensure that RF safety is properly managed, managers and supervisors
must arrange that risk assessments are carried out for: -
i) employees whose work may expose them to RF fields
ii) the design of installations involving RF transmitters and antennae which are capable of
producing field strengths above the reference levels
iii) Work locations where reference levels may be exceeded.
3.5 Employee Responsibilities
a) It is the duty of the employee to co-operate with their managers or supervisors in
complying with the safe systems of work specified for their protection in relation to
all activities or tasks associated with RF working.
b) Employees are responsible for ensuring that they do not work within areas that may be
subject to RF radiation above the relevant reference level. Access to areas of possible
risk such as those detailed within Appendix B must be avoided if suitable monitoring
equipment is not available or if previous measurements have indicated that the levels of
RF radiation is not safe to work in.
c) Employees must report to their manager or supervisor, antennae (irrespective of who
operates them) installed in positions that might compromise the RF safety of the
Company’s employees or others. (The most common example is the installation of an
antenna whose exclusion zone encroaches into an access route or work platform).
d) Employees must notify their manager if they have an active surgic al implant (e.g.
heart pacemaker, insulin pump) or any passive metallic implant (e.g. plates and pins
used to repair broken bones) if their work involves exposure to RF fields at
telecommunications sites.
e) Employees must be responsible for the care and correct use of personal monitors or
any other RF measurement equipment issued to them for safety reasons and ensures
they have received adequate technical and safety training and are confident in their
ability to carry out their assigned tasks safely.
f) Employees working as designers must ensure that all installations of new RF
transmitters are designed so that: -
i) the fields they generate do not exceed the reference level in any area
accessible to people
Or
ii) Accessible areas where the reference levels are exceeded are identified
as exclusion zones by warning signs, conspicuous marking and preferably
by physical barriers to entry.

4. RF Field Strength Measurement
Actual RF field strength should be measured before entry into an exclusion zone or where the
risk assessment of a location indicates that RF field strengths may approach or exceed the
reference level, or the field strength is unknown.
Equipment available for measuring RF field strength are described within the following
sections and only a competent person should use the equipment selected.
The Company Policy regarding the issuing of personal monitors is one per person.
Personal monitors provide a means of continually monitoring RF field strength to which an
individual is actually exposed. These types of monitor provide broad coverage at a range of
frequencies. More than one monitor could be required to cover all the frequencies present at
multi-user locations where a mixture of microwave, cellular telephone and VHF/UHF
transmitters might be present.
Personal monitors are ideally suited to multi-user sites as they automatically provide a sum
of the field components over the range of frequencies for which they are designed and
provide an alarm trigger based on the equivalent power density of the combined fields. This
eliminates the need for any complex measurements or calculations.
4.2 Area Monitors
This type of monitor is unattended and continuously measures RF field strength with an alarm
being activated to warn when reference levels are exceeded. These monitors are most
suitable for: -
i) remote monitoring
ii) populated areas where issues are infrequently expected
iii) areas visited infrequently
iv) Sites which may experience RF field strength that fluctuates above and
below the reference levels.
4.3 Survey Instruments
Survey instruments independently measure the electrical and magnetic components of RF
fields. Survey instruments can be used to pinpoint RF leakage from feeder cables and
other sources by using probes that permit measurements in relatively inaccessible places.
Additionally survey instruments allow the detector to be physically separated and if
required electrically de-coupled from the meter. The detectors on survey instruments
provide a broadband response which is weighted to reflect the different reference levels at
different frequencies.
The operation of this type of equipment and the interpretation of its measurements require
skill, experience and knowledge on the part of the operator. Measurements for safety
reasons should only be carried out by a competent person who has successfully completed
their training in the use of the equipment.

4.4 RF Alarms
RF alarms are activated on personal and/or area monitors when the RF field strength has
exceeded the reference levels. When the alarm is activated work should be suspended
and personnel should withdraw to a point at which the monitors do not sound.
If individuals can rearrange their work to another safe area then they should do so. If this is
not possible then they should remain at a safe distance either until the monitors identify the
level is below the reference levels or until the actual RF field strength can be confirmed by
measurement survey.
Where possible the identified problem antenna should be switched off provide this does
not require entry into the suspected area which triggered the monitor alarms.
Additionally, ensure that the monitor or alarm has been checked and is functionally correctly.
4.5 Potential or Suspected RF Exposure
The use of RF alarms and personal monitors described in sections 4.1, 4.2 and 4.4, reduc e
the risk of potential or actual RF exposure to individuals. Additionally the exclusion zones
identified for the different types of antennae coupled with the reference levels for safe
working levels that are set well below dangerous levels provide good safety margins to those
individuals working in these areas. The personal safety alarm devices (e.g. Nard alert) used
by many climbers, trigger at 50% of the ICNIRP occupational power density guidelines.
However, in the unlikely event that a potential, suspected or actual exposure occurs then the
affected individual(s) should be taken to the nearest hospital and staff should be informed of
the nature of the incident. All incidents in which an individual believes that they may have
been exposed to excessive RF power densities, whether accompanied by symptoms of ill
health or otherwise must report this immediately to the individual’s Manager and GTL’s
accident procedure must be adhered to and an appropriate investigation will be conducted.
Only if possible and without the need for any individuals to enter the area suspected of
excessive RF levels, should equipment be isolated. The working area(s) suspected of
producing excessive RF levels should be cordoned off with a suitable safe zone to prevent
entry into where the suspected / actual excessive levels are and appropriate signage must
be displayed. The area will need to be surveyed by qualified and competent individuals to
determine the actual levels prior to any further work or access being granted to the area
suspected of being affected.
Some of the symptoms which may be exhibited due to excessive exposure are: -
• a metallic taste in the mouth
• sudden headaches
• gentle warming of the joints
• a noticeable increase of body temperature
• a general feeling of sickness
RF exposure from VHF (30 – 300MHz) can particularly affect individuals who have ‘pinned’
bone fractures or any other medical conditions involving metal or plastic implants or who
depend upon cardiac pacemakers.
At medium and high wave radio sites the mast itself acts as the antenna using the ground
and underground copper wire as a ground plate reflector, therefore it is possible to find high
levels of RF at ground level on these types of sites. The RF monitor should always be on and

functional prior to approaching masts with these types of antennae on them and caution

Should be applied with the use of reduced power and shutdowns. Medium wave frequency
masts are used for “live” radio frequency currents, at voltage levels high enough to cause RF
burns to any part of the body which comes into contact with them. Any large metal objects
within the immediate vicinity can also act as a receiving antenna which may pick up enough
energy to cause RF burns if contact is made. Additionally working in the vicinity of band 2
broadcast antennae is considered to pose an elevated risk because of the susceptibility of
the human body to the type of wavelength and therefore maximum caution should be
applied with the use if reserve antennae, reduced power and shutdowns.
4.6 Summary
Any of the types of systems described in sections in) – IV) could be used to determine the
RF field strength in a working location. Selection of the correct equipment to give adequate
coverage of the required range of power levels, frequencies and circumstances of use will
be the main requirement.
As such, no recommendations of specific manufacturer's products are provided within this
Policy, however further information on personal monitors is provided in Section 6.0.
For most employees who are likely to work in areas of possible risk from RF fields, use of
the personal monitor will be the most convenient and most appropriate method. Personal
monitoring enables the user to move freely through areas of varying and unknown RF field
strength and provide a warning before the reference level is exceeded.
5.0 UK and International Standards
The relevant international safety standard is the guidance published by the International
Commission for Non-Ionising Radiation Protection (ICNIRP) and the ICNIRP basic restrictions
are also detailed in Appendix A.
A graphical representation of electrical and magnetic field strengths and power density
provides the easiest means of understanding the complex standards. Power density is not
directly measurable even though it is often quoted and is displayed on instrumentation as an
equivalent to the electric or magnetic field that is actually being measured. This data is
presented as a reference level which varies with the frequency of the field and should be
interpreted as an action level for limiting exposure and thus meaning that people can safely
work for indefinite periods in fields that are below the reference level.
Where a field is found to be above the reference level, it is possible that harm could be
done to those exposed and the basic safety restrictions must then be considered.
Reference levels are set to ensure that none of the basic restrictions on specific absorption
rates, magnetic flux density, power flux density and induced current density are exceeded.
Transmissions at different frequencies can combine to produce harmful effects and
personal monitors measure the total field from all sources within their frequency range.

6.0 Safe Systems of Work
Safe systems of work should be prepared for all activities at Company and other
managed sites where employees, contractors or others may be exposed to RF fields
above the reference levels.
The basic elements of any such system would comprise the following: -
6.1 Risk assessment – Undocum ented /U nregistered RF Levels
Assume that there is always a possible health risk arising from exposure to RF fields at sites
equipped with radio transmission equipment and with this assumption, it will be necessary to:
-
i) ensure that each individual has and uses their personal monitor
ii) identify the range of frequencies to be found at the site
iii) Implement a “stop work and review” process when an alarm is triggered on a monitor.
6.2 Risk assessment – Documented RF Levels
a) Assemble all available documented information on field strength levels likely to be
encountered in the work area and in the access ways which approach it. If the information
seems incomplete or too old to be trustworthy then acquire new up to date information which
can be obtained via: -
i) The appropriate technical authorities such as site owners, managing agents,
licensed operators or equipment suppliers
ii) Completion of a new RF survey
OR
b) Where current field strength information is up to date and within the reference level then
work may proceed but personal monitors must continue to be used where RF fields exist.
If the current field strength is above the reference level then proceed to the section on
“Control of Risks”.
6.3 Control of Risks
Control measures must be formally established for situations in which work areas
are subjected to RF fields above the reference level.
In the absence of a system-based mechanism then control measures can be accomplished by
the operation of a “Permit to Work” which specifies the location, details of the work, the start
time, duration of the work and the control measures which are nec essary to reduce the fields
to safe levels.
Refer to Appendix C for an example of a Permit to Work system.
Permits to Work should be issued by the manager or supervisor responsible for
commissioning the work within the area(s) where RF fields are above the reference level. The
manager or supervisor must certify that the appropriate control measures have been affected
before the start of, and for the specified duration of the Permit to Work.

The control measures would normally comprise either reduction of output power or switching
off one or more of the transmitters which are producing the high field levels. In either case
the manager or supervisor must establish a secure means of maintaining control for the
duration of the work which would typically be achieved by isolation of the power supply to a
transmitter or by locking its power output control at the required level.
6.4 Management
Safe systems of work require a process that includes risk assessment, planning of work
activities, assessment of individual competence, monitoring, supervision and the provision of
information, instruction and training.
The application of management controls for adherence to the safe systems of work, the
use of the required control measures and ensuring competent individuals perform the
required tasks or activities is via the monitoring process.
6.5 Personal monitors
Personal monitors should be worn at all times in work areas where RF fields exist.
“Narda” personal monitors encompass the principal systems found on multi-user sites that
may have exclusion zones. Other types of monitor covering a similar range of frequencies
will be equally acceptable.
6.6 Exclusion Zones
The exclusion zones for the types of antenna commonly found on sites where GTL personnel may
work are detailed in Appendix B. Where exclusion zones occur in accessible areas, these should be
indicated by warning signs and markings on a roof or on the structure around an antenna and
additionally there may be physical barriers against entry into the risk area.
If work within an antenna exclusion zone is required, the RF power source must either be
switched off or reduced in output to below the reference level. On / off and reduction
controls must be securely isolated or locked to prevent re-connection without the knowledge
of those at work (accidental or otherwise). Antennae should only be approached where it is
absolutely necessary and the absence of barriers or markings does not indicate safe
conditions in an area close to an antenna.
When a powered antenna needs to be approached to perform work on or near to it, then
this must only be done after establishing that the work can be performed from a position of
safety.
Particular care should be taken to avoid direct contact with the radiating elements
of neighbouring antennae.
Personal monitors should always be worn by employees or other individuals working
on behalf of GTL whilst working in these circumstances.

6.7 Transmitters
Power sources designed to generate RF signals for transmission to a remote receiver
are known as transmitters.
The output from a transmitter with an unterminated waveguide or coaxial cable port
produces a concentrated local RF field which may exceed the reference level. It is therefore
essential that work should only be carried out in the vicinity of powered transmitters when
output ports are terminated by connection to a feeder, test connector or load (i.e. the
source is switched off and securely isolated) which prevents the emission of high levels of RF
energy into the surrounding air space.
6.8 Feeders
Feeders are the physical connections between a transmitter and an antenna. The common
types of feeder are elliptical waveguide and coaxial cable but square, circular and
rectangular waveguide can be used.
“Feeder” channel RF signals from a transmitter to an antenna and the RF energy within the
“feeder” is virtually the same as that at the transmitter output port. The energy will be
released into the surrounding air space if there are any breaks in the “feeder” or its
connectors. Mechanical damage is often the cause of RF leakage from feeders.
Leakage can result in a degradation or disruption of service. Maintenance engineers
investigating the fault are inevitably drawn towards this potential danger whilst inspecting the
feeder. RF measuring equipment must be used for this type of work as it not only indicates
the location of a leak but aids the protection of the individuals within the vicinity. This
equipment must cover the frequency being carried by the feeder.
Any operation involving the disconnection of a feeder joint may only be carried out
after the power source is switched off and securely isolated. Leaking feeders must
be disconnected from power before any repair work is initiated and must remain
locked off throughout the course of the work.
Any other work where accidental leakage of RF energy from a feeder may occur should be
similarly controlled.
In some cases, feeders are labelled to indicate their function and / or ownership. A feeder
bearing no label or identification must be assumed to be carrying RF power. Only when it
has been proven that no live transmitter is connected to it then individuals working on or
near to the feeder can perform the required tasks or activities.
6.7 Training
Individuals working with RF systems must be competent by having the required technical
training, skills, qualifications and experience coupled with the specific knowledge of that
equipment. The training must include the correct use of personal monitors or any other
measuring equipment to ensure that a safe system of work is complied with (Appendix D for
details).
Individuals who work with antennae and feeder systems should have the appropriate level
of working at height training – refer to the Climbing and Work at Height Policy for the type
of course required in relation to the level of climbing and working situation.

Appendix A
The reference levels have been set in order to achieve a number of basic restrictions on
Specific Absorption Rate (SAR) and induced current density. The ICNIRP restrictions are
below.
Basic Exposure Restrictions for Frequencies 1 kHz - 10 GHz: -
Exposure
Characteristic
Frequency
Current
density -
Whole
body
Localised
SAR (head
Localised
SAR
range head & trunk
(mA/m ²)
(rms)
average
SAR
(W/kg)
& trunk)
(W/kg)
(limbs)
(W/kg)
Occupational 1 kHz – f/100
100 kHz
Occupational 100 kHz - f/100 0.4 10 20
10 MHz
Occupational 10 MHz - - 0.4 10 20
10 GHz
Public 1 kHz – f/500
100 kHz
Public 100 kHz - f/500 0.08 2 4
10 MHz
Public 10 MHz - - 0.08 2 4
10 GHz
Notes for the above: -
a) F is frequency in hertz.
b) Due to electrical inhomogeneity of the body, current densities should be averaged over
a cross section of 1 cm² perpendicular to the current direction.
c) For frequencies up to 100 kHz, peak current density values can be obtained by
multiplying the rms value by 2. For pulses of duration tp, the equivalent frequency
to apply to the basic restrictions should be calculated as f = 1/ (2tp)
d) For frequencies up to 100 kHz, and for pulsed magnetic fields, the maximum current
density associated with the pulses can be calculated from the rise/fall times and the
maximum rate of change of magnetic flux density. The induced current density can
then be compared with the appropriate basic restriction.
e) All SAR values are to be averaged over any 6 minute period.
Basic ICNIRP restrictions for power density for frequencies 10 GHz - 300 GHz: -
Exposure characteristics Power density W/m²
Occupational exposure 50
General public 10
Notes for the above: -
a) Power densities are to be averaged over any 20 cm² of exposed area and any 68/f
1.05
minute period (where f is the frequency in GHz) to compensate for progressively
shorter penetration depth as the frequency increases.

b) Spatial maximum power densities, averaged over 1 em 2 should not exceed 20 times
the values above.

Appendix B
Antennae Types and Exclusion Zones
i) Sector Antennae
The signals from mobile telephony sector antennae form a rectangular exclusion zone which
extends above, below and behind the antenna as well as to the front and sides.
All Operators’ sector antennae have different size exclusion zones and the following
measurements are the largest dimensions of antenna exclusion zones. In the absence of
any site-specific information, these should be used as the smallest safe size of
exclusion zone:
Above / below 0.75 metres
Behind 0.5 metres
Sides 2.0 metres
Front 0.5 metres
Notes: -
 Individuals must not work within an antenna exclusion zone without arranging for it
 to be powered down or reduced in output. 
 Individuals should not approach a sector antenna without using a personal monitor. 
 Sector antennae may be found in a range of colours and may be either solid or formed
from a wire mesh or grid. All variants will be oblong in shape when viewed from the
front. 

ii) Omni Antennae
The signals from mobile telephony, paging and other omni antennae form a cylindrical
exclusion zone that extends above and below the antenna as well as in a radius around it.
All Operators’ omni antennae have different size exclusion zones and the following
measurements are the largest dimensions of antenna exclusion zones. In the absence of
any site-specific information, these should be used as the smallest safe size of exclusion
zone:
Above / below 0.5 metres
Radius 4.0 metres
Notes: -
 Individuals must not work within an antenna exclusion zone without arranging for it
 to be powered down or reduced in output. 
 Individuals should not approach an omni antenna without using a personal monitor. 
 Omni antennae may be found in a range of colours and may be thicker, thinner, longer
or shorter than that illustrated above. 

iii) Microwave Antennae
The signal from a microwave antenna emerges as a "pencil beam" from the centre of
the antenna. The power transmitted from microwave links operated by fixed and
mobile telephony operators does not reach harmful levels.
However, individuals must not pass in front of a microwave antenna since this will
interrupt or degrade the communications link.
Notes: -
 There are no set exclusion zones 
 Exclusion zones using barriers to deter access in front of antennae serve the purpose of
preventing obstruction of the communications link. 
iv) Satellite Stations (Dish or Bowl Antennae)
Large-diameter earth station antennae will have systems that prevent access to the
reflector bowl during transmission activity. Access is normally controlled by mechanical
interlocks (Castell keys) between the entry door and the transmitter.
VSAT earth station antennae, such as those operated by news agencies or
incorporated within navigation and paging systems have no exclusion zones but may have a
designated exclusion zone immediately in front of the antenna to prevent disruption of
signals.

Example of an RF Permit to Work
i) Details
Name of Employee / Contractor /
Sub-contractor / Third Party
Location of work to be completed
(e.g. Building / Work Area)
Person controlling the work: -
Name
Job Title
Telephone No: - Work / Mobile
ii) Description of the work to be undertaken: -
Required commencement Date Time
Required completion Date Time
iii) Control Measures Required (* - Delete as appropriate): -
Power has been removed* / reduced*to the following antennas: -
i) iii)
ii) iv)
The associated controls securely locked
Yes / No *
If No, detail why
Exclusion zones relating to all hazardous antennas have been established and clearly
marked in respect of the work area and all access ways to and from it Yes / No *
If No, detail why
Provide any information on additional control measures, precautions, restrictions, limitations
or conditions, including any special hazards and details of any time restrictions
Copies to
i) Employee / Contractor / Sub-contractor / Third party
ii) GTL Line Manager / GTL employee controlling the work
iv) Authorisation
This permit is authorised for the scope and duration of the work as stated
a) Issuer: -
Name
Signed
Job Title Date
b) Received by: -: -
Name
Signed
Job Title Date

Training Courses
RF Safety Awareness Course Content (½ day, valid 3 years)
Electromagnetic spectrum
Effects of non-ionising radiation
Exposure standards
Antenna recognition
Personal protection
Use of personal RF monitor equipment
Signs and symptoms of RF exposure
Susceptible organs and first aid
Rooftop and RF Safety Awareness Course Content (1 day, valid 3 years)
Working at Height Regulations and associated legislation
Activities and accident causation
Common hazards
Access and egress using ladders (fixed and portable)
Planning and preparation
Electromagnetic spectrum
Effects of non ionising radiation
Exposure standards
Antenna recognition
Personal protection
Use of personal RF monitor equipment
Signs and symptoms of RF exposure
Susceptible organs and first aid
Advanced Climber with Tower Rescue (2 days, valid 3 years)
Relevant H&S legislation
Risk assessment and associated
hazards dealing with RF hazards
Dealing with emergencies - suspension trauma
etc PPE use - checking and fitting
Advanced climber techniques
Selection and use of anchor points
Pre-use inspection, storing and maintaining of PPE
Precautions to be taken with tools and equipment when working at height - signing and
guarding
Equipment handling - (maximum 20kg)
Abseil (cut) rescue techniques in simple descents

Advanced Tower Climber Refresher Course Content (1 day, valid 3 years)
Legislation and standards
Fall dynamics and protection principles
Selection and inspection of fall arrest equipment
Working at heights categorisation
Simple lifting techniques
Generic and specific hazard identification and assessment
Open steelwork descent/ascent
Temporary fall arrest systems for exposed locations
Fall protection equipment and systems
Practical training and assessment
Emergency procedures
Tower/Structural Rescue Course Content (1 day, valid 1 year)
Legislation and Standards
Rescue Plans
Casualty care
Rescue Equipment
Selection and establishing anchor points
Abseiling using a selection of descent devices
Emergency Procedures
Practical assessment - cut away abseil rescue

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