Non-Ionising Radiation

1      Introduction

The Policy highlights the relevant legislation or standards that govern exposure to non-ionising radiation and the practical steps that departments should take in order to ensure exposure is as low as reasonably practicable (ALARP).

The term non-ionising radiation refers to any form of electromagnetic radiation that does not have sufficient energy to ionise atoms.  Although there are many sources of non-ionising radiation within the University (e.g. lighting, microwave ovens, induction heaters etc.), very few will actually pose a significant risk.  This is due to the low level of radiation that individuals are actually exposed to or through the body’s natural aversion response e.g. blinking, thermal discomfort.  Sources that do pose a risk are generally associated with a specific research project or only pose a risk during maintenance activities when existing controls are removed or modified. 

The Policy is principally aimed at those activities where there is a significant risk of exceeding exposure levels.  In these cases, documented risk assessments and specialist controls would be necessary.  For the vast majority of non-ionising radiation sources there will be suitable controls already in place and so departments will simply need to review these controls as part of a general risk assessment or inspection.

The Policy does not cover ionising radiation (i.e. electromagnetic radiation that can ionise atoms).  This is covered by University Policy Statement ‘S1/12 - The general local rules for work with sealed and unsealed radioactive substances’ and is issued directly to relevant departments.

2      Departmental actions

(a)  The head of department must nominate a suitable person to coordinate a review of all non-ionising radiation sources within the department.  The review should identify all possible sources of non-ionising radiation and consider:

(i)    Whether the existing risks are Trivial or as low as reasonably practicable under normal use or conditions and in line with relevant exposure limits or standards (see below).

(ii)   Whether anyone might be more sensitive to the non-ionising radiation as a result of their work e.g. anyone known to have a pre-existing medical condition, individuals using photo-reactive chemicals, individuals carrying out non-routine maintenance or servicing.

(iii)  Whether a detailed risk assessment is required.

(b)  Departments may wish to incorporate this review as part of their annual safety inspection.  The checklist in Appendix 1UPS S4/11 Appendix 1 (22kb) is provided as a basic overview of the points to consider.

(c)  If there is a potential risk of harm from a source, the Head of department is responsible for ensuring a documented risk assessment is completed and suitable controls implemented. 

(d)  Relevant exposure limits or standards must not be exceeded, unless fully justified within a documented risk assessment.  In any event, exposure must be kept as low as is reasonably practicable through the implementation of suitable control measures.  Suitable controls might involve a combination of engineering (e.g. screens, enclosures, interlocks), administrative (e.g. training, supervision, restricted access, warning signs/labels) and finally, personal protective equipment.

(e)  Where risk assessments are necessary, a suitable person should be nominated to complete the assessment.  For research related sources, the responsibility for completing these assessments would be the relevant supervisor.  For building related sources, the department would normally be responsible but if there is any doubt the ‘Estates Regulations’ should be consulted.

(f)      Advice on non-ionising radiation should be obtained from the Departmental Safety Officer.  Departments may also consult the University Safety Office, particularly where there is uncertainty over exposure limits and if measurements or calculations are considered necessary.

(g)  The University’s Non-Ionising Radiation Protection Advisory Group has been established to advise the University Health and Safety Management Committee (HSMC) on all matters concerning non-ionising radiation work.  In order to fulfil this duty, the University Safety Office may request information from departments as to the type of non-ionising radiation sources identified.

3      Sources of non-ionising radiation

Electromagnetic radiation is transmitted as waves or packets of energy (quanta).  The waves travel at the speed of light (i.e. 299,792,458 m/s) and the frequency of the oscillations is inversely proportional to the wavelength, such that:

              Speed = Frequency (Hz) x Wavelength (m)

Non-ionising radiation is therefore sub-divided into:

  • Optical Sources – Wavelengths between 100 nanometres and 1 millimetre
  • Electro-Magnetic Fields – Static magnetic and time-varying electric, magnetic and

electromagnetic fields with frequencies up to 300 gigahertz (or 1 mm)

 

(a)  Optical radiation sources

Optical radiation is categorised according to wavelength: 

  • Ultraviolet radiation           –          100nm to 400nm
  • Visible                                –          400nm to 780nm
  • Infrared                             –          780nm to 1mm

The health effects associated with optical radiation are summarised in the table below:

Special RegionEffects upon the eyeEffects upon the Skin 

UV-B

(280-315nm)

Photokeratitis

(“snow blindness” or “arc eye”)

Erythema (“sunburn”)

Accelerated skin ageing process

Increased pigmentation

  
 

UV-A

(315-400nm)

  Photochemical cataract

 Skin darkening

Photosensitive reactions

 Skin Burns
 

Visible

(400-780nm)

Photochemical (“blue light hazard”)

and thermal retinal injury

  

 Skin darkening

Photosensitive reactions
 

IR-A

(780-1400nm)

  Cataract, retinal burns  

 Skin darkening

Photosensitive reactions
 

IR-B

(1.4-3.0µm)

  Aqueous flare, cataract, corneal burns  

 Skin darkening

Photosensitive reactions
 

IR-C

(3.0µm-1mm)

  Corneal burns  

 Skin darkening

Photosensitive reactions

 

Optical radiation sources are either natural (e.g. sunlight) or artificial (e.g. lighting).  There is no direct legislation that covers exposure to natural sources of optical radiation.  However, the general requirements of the Management of Health and Safety at Work Regulations 1999 apply e.g. risk assessments should consider the potential exposure of anyone who might work for extended periods in direct sunlight.  Further information on exposure to sunlight is provided in the University Policy Statement ‘OHS1/11 - Skincare in the Workplace’.

For artificial sources of optical radiation, the Control of Artificial Optical Radiation (AOR) at Work Regulations was introduced in 2010.  These regulations legally implement ‘Exposure Limit Values (ELV)’ for artificial sources.  However, the Health and Safety Executive’s guidance[1] states that the majority of light sources are safe or ‘Trivial’ and in that sense, do not require any specific action other than routine maintenance and relevant instruction of personnel.  Examples include:

  • All forms of ceiling-mounted lighting that have diffusers over bulbs or lamps.
  • All forms of task lighting including desk lamps and tungsten-halogen lamps fitted with appropriate glass filters to remove unwanted ultraviolet light.
  • Photocopiers.
  • Computer or similar display equipment, including personal digital assistants (PDAs).
  • Gas-fired overhead heaters.
  • Any exempt or Risk Group 1 lamp or lamp system (including LEDs), as defined in British Standard BS EN 62471.
  • Any Class 1 laser light product, as defined in British Standard BS EN 60825-1, for example laser printers and CD players.

The HSE’s guidance also describes sources that have the potential to cause harm only if they are used inappropriately or modified.  Therefore, again under normal circumstances no specific action is required other than routine maintenance and relevant instruction of personnel. 

Examples include:

  • Ceiling-mounted fluorescent lighting without diffusers over bulbs or lamps.
  • High-pressure mercury floodlighting.
  • Desktop projectors.
  • Vehicle headlights.
  • UV insect traps.
  • Any Risk Group 2 lamp or lamp system (including LEDs), as defined in British Standard BS EN 62471.
  • Class 1M, 2 or 2M lasers, as defined in British Standard BS EN 60825-1, for example low-power laser pointers.  

All other sources might pose a reasonably foreseeable risk of harm to the eyes and skin and will need to be appropriately managed.  Examples of potential hazardous sources are:

When conducting a review of artificial optical radiation, departments should consider which of the above risk categories apply.   If there is any doubt regarding the potential to cause harm, an evaluation of the actual exposure against the exposure limit might be necessary.  However, calculating whether an exposure limit value is exceeded is difficult, as a number of factors are taken into account (e.g. wavelength, energy, and exposure times). 

Before undertaking measurements, departments should consult their suppliers of equipment for information on optical radiation emission.  For example, lamp and lamp systems are now classified according to four risk categories in accordance with British Standard BS EN 62471.

  • Exempt
  • Risk Group 1 (Low-Risk)
  • Risk Group 2 (Moderate-Risk)
  • Risk Group 3 (High-Risk)

In addition, the Health Protection Agency (HPA) has produced a non-binding guide to artificial optical radiation (link below) that provides examples of sources and under what circumstances the exposure might be significant. 

http://www.hse.gov.uk/radiation/nonionising/aor-guide.pdf

Departments may refer to this guide and make a reasonable judgement without the need for complicated measurements or calculations.  If there is any uncertainty, the University Safety Office should be contacted for advice on relevant measurements.

If after implementation of suitable controls it is still foreseeable that someone might be exposed above the exposure limit, further actions could be necessary.  For example, investigations of over-exposure, restrictions on access to the source, medical examination or health surveillance.  Departmental Safety Officers should be consulted and where necessary, the University Safety Office.

Further information on the control of some specific types of artificial optical radiation is provided in the appendices and other policy statements:

(b)  Electro-magnetic fields (EMF)

Electro-magnetic field radiation is categorised according to frequency:

  •   Radiofrequency radiation (inc. microwave) - 100kHz to 300GHz
  • Extremely Low Frequency (inc. static and magnetic fields) - <100KHz

The established adverse health effects associated with electro-magnetic field radiation are summarised in the table below:

 

Spectral RegionEstablished Effects
Radiofrequency

Direct Effects

  •   Nerve cell, muscle stimulation
  •   Resistive tissue heating (current flow)
  •   Tissue heating from RF absorption
  •   Hearing RF pulses

Indirect Effects

  •   Contact current burns
Extremely Low Frequency
  • Induction of electric fields and currents in body tissues

 

At present, there is no specific legislation that covers exposure to electro-magnetic field (EMF) radiation, although a European Directive is currently being considered.  However, the Management of Health and Safety at Work Regulations 1999 do apply.  In order to demonstrate compliance with these regulations and specifically the requirement to adequately control exposure, the Health Protection Agency (HPA) and National Radiological Protection Board’s (NRPB) advice should be used as the standard when assessing exposure e.g. ‘Advice on Limiting Exposure to Electromagnetic Fields (0-300GHz), Volume 15 No.2 2004’, available at the following website:

http://www.hpa.org.uk/Publications/Radiation/NPRBArchive/DocumentsOfTheNRPB/

The same principles as outlined in Section 2 should be applied e.g.

  • Departments must identify their sources of electro-magnetic field radiation
  • Departments must consider individuals exposed
  • Departments must review existing controls
  • If a potential risk of harm remains, a documented risk assessment must be completed and relevant controls identified
  • Risk assessments should consider the need for measurements or calculations in order to demonstrate compliance with current standards.  Again, suppliers of equipment should be approached for information and advice on the equipment’s safe use.  The Safety Office should be consulted if there is any uncertainty.
  • Controls can be engineering, administrative and personal protective equipment.
  • If after implementing controls the exposure levels are still exceeded, as outlined in the NRPB’s advice, this must be documented in the risk assessment and the level reduced as far as reasonably practicable.

Examples of equipment that might be assessed as Trivial or controlled as low as reasonably practicable under normal conditions are:

  • Computer and IT terminal equipment using wireless technology
  • Electricity supply networks
  • General electrical appliances
  • Work outside ‘exclusion zones’ of base station antennas

Examples of equipment that might require further assessment are:

  • Dielectric heating and welding
  • Diathermy medical equipment with time averaged power >100mW
  • Induction heating
  • Industrial microwave heating and drying
  • Magnetic Resonance Imaging or Nuclear Magnetic Resonance
  • Radars
  • RF plasma devices and vacuum depositing and sputtering
  • Work inside ‘exclusion zones’ of base station antennas

Further information on the control of some specific sources of electro-magnetic field radiation is provided in the appendices. 

The University’s Non-Ionising Radiation Protection Advisory Group will review relevant exposure limits in respect to departmental risk assessments and any new guidance, standard or regulations.

4      Glossary

ALARP - as low as reasonably practicable

AOR - artificial optical radiation

ELF - extra low frequency

ELV - exposure limit value

EMF - electro-magnetic fields

HPA - Health Protection Agency

ICNIRP- International Commission on Non-Ionizing Radiation Protection

MHSWR - Management of Health and Safety at Work Regulations, 1999

MRI - magnetic resonance imaging

mT -  millitesla

NMR - nuclear magnetic resonance

NRPB - National Radiological Protection Board

T – tesla

UV – ultraviolet

THIS STATEMENT FORMS PART OF THE UNIVERSITY SAFETY POLICY.  PLEASE AMEND THE INDEX.

October 2011      

For any queries regarding this policy please contact Brian Jenkins at the Safety Office on tel. no. 70811                                                                                                           

 

[1] HSE Guidance for Employers on the Control of Artificial Optical Radiation at Work Regulations (AOR) 2010

03 October 2011

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Appendices