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Section 12: Precautions for Working with Non-Ionising Radiation

Non-ionising radiation is electromagnetic radiation covering the range of wavelengths from 100nm (Ultra Violet) to > 1000km (Electromagnetic fields EMF).

The types of non-ionising radiation are:

Optical Radiation
Ultraviolet (UV) Visible Light 
Infrared (IR) Laser
 
Electric and Magnetic Fields (EF/EMF)
Radiowaves (includes Microwaves)

The highest energy is emitted by UV with EMF being at the lower energy end of the spectrum.

12.1 Optical Radiation

The tissues of the body affected by optical irradiation are the skin and eyes. The biological effects are as follows:

 Skin  Eyes
 Suburn (UV)  Pain, light sensitivity, tearing (UV)
 Ageing (UV)  Cataract (UV and IR)
 Cancers (UV)  Burns and retinal damage (Vis, IR)
 Burns (Visible and IR)  

12.1.1 UV Radiation (UVR) (100nm to 400nm)

Typical sources of UV within the University are:

      • Sun (outdoor workers, field trips)
      • Electric arc welding
      • Mercury, metal halide and high-energy discharge lamps (e.g. curing, drying, printing processes
      • Certain laboratory equipment (spectrophotometers, transilluminators etc.)

a) Sun

People working outdoors for prolonged periods, are likely to be exposed to UVR from the sun, even on cloudy days. Those travelling aboard on field trips and other University business are also at risk of exposure.

A combination of the following precautions should be taken:

      • Use of shade structures and awnings made from material offering sufficient protection.
      • Planning and timetabling for outdoor work to minimise exposure to direct sunlight during periods of greatest intensity and to limit the total duration of exposure.
      • Use of UVR protective clothing (loose with close weave).
      • Wear a wide brimmed hat.
      • Use protective eyewear with side protection.
      • Where sun cannot be adequately protected by clothing, some people may choose to apply sunblock or high SPF suncream. Apply generously 15 minutes in advance of exposure and repeat application frequently.

b) Electric Arc Welding

Electric arc welding involves intense forms of UVR. Staff involved in this work must have received appropriate training. The following precautions must be taken:

      • Work-piece and work area must be shielded and enclosed as much as possible.
      • Restrict access to area where possible and prevent inadvertent exposure.
      • Both eyes and skin must be protected using appropriate visors and clothing.
      • Protect others that have to be in the area.

c) Laboratory Equipment

Laboratory UVR sources such as transilluminators and gel documentation equipment usually emit UVR in the region of 280nm to 400nm. Detailed information and guidance on their safe use can be found on the Safety Office website. Eye and skin protection is required.

12.1.2 Infra-red Radiation (IRR)

Intense IRR sources can result in skin burns or a risk of cataracts developing. The hazard is associated with furnace work and powerful heating and drying processes using IRR. Glass or metal doors with interlocks and warning notices are recommended.

12.1.3 Lasers

The use of lasers in the University is subject to the University Code of Practice for Laser Safety PDF format. The following summarises many of the key aspects of this. Lasers embedded in office equipment such as printers, CD-ROM drives and class 1 or 2 laser pointers are not considered to be hazardous are not subject to these controls.

Work with laser systems may only be undertaken after assessment of the hazards associated with it and providing that suitable facilities, local procedures and organisational arrangements are in place. Users must be trained and competent and be adequately supervised.

Most types of laser operating in the visible and near infrared regions are sufficiently intense as to represent a hazard to the eye. Although damage may be caused to all parts of the eyes, the most vulnerable part is the retina, on which the beam may be focussed by the eye lens resulting in the destruction of tissues and the creation of permanent blind spots. High power lasers can also damage the skin.

It is important to establish whether the laser used produces a beam in the visible part of the EM spectrum or not. In the case of the latter, personnel may be unaware that they have been exposed to laser radiation unless clear warning is given that the laser is operating.

Laser hazard is identified by classification of the laser (1 to 4, with 3 and 4 posing greater hazard). The class of each laser must be marked clearly by the supplier. Lasers falling into class 3 (either 3R, the lower hazard subdivision of this class, or 3B, the higher hazard subdivision), or class4 must be registered with the Safety Office. Laser registrations must be accompanied by a risk assessment and a Laser Survey Form.

Users of class 3 or 4 lasers must also be registered with the Safety Office. Users of class 3B and 4 lasers must attend for an eye examination at Occupational Health. In the event of a suspected eye exposure to such a laser the user must notify their supervisor or School Laser Supervisor and a further examination will be arranged.

Safety measures usually concentrate on making the beam path inaccessible, thus preventing exposure. In many applications (i.e. particle sizing, interferometry and Raman spectrometry) the laser will be enclosed. Where research applications with unenclosed high power beams are involved, a mixture of engineering controls, administrative procedures and personal protection will be needed.

Lasers should be operated with as high a background level of illumination as possible to ensure that the pupil of the eye is small and in some cases it may be advisable to wear protective goggles. The goggles to be worn should be appropriate to the wavelength of the laser beam being used.

Care should be taken to check the paths of all possible reflections and if necessary non-flammable opaque screens should be used to protect personnel.

There is a University Laser Safety Officer and Schools using Lasers have appointed School Laser Supervisors. The University Laser Safety Officer can be contacted via the Safety Office.

A video entitled "Laser Safety in Higher Education" is available from the Safety Office and describes the hazards and controls in detail. All users of class 3 and 4 lasers should attend the introductory session on laser safety as part of their laser training programme. All users should receive appropriate local training in the systems that they will be using.

Warning notices should be displayed where Lasers are in use. A laser beam should never be looked along directly.

laserhazard

Laser hazard label: Symbol and border in black - Background yellow

12.2 Electric and Magnetic Fields

Electric and magnetic fields arise from the generation, transmission, distribution and use of electricity and in broadcasting and telecommunications, radar, induction and dialectic heating.

12.2.1 Electric Fields

Electric fields are produced as the voltage forces electricity along a wire. The higher the voltage the stronger the field produced. Electric fields around a wire only cease to exist when the appliance is unplugged or switched off at the socket. They will still exist however around the cabling within the wall or infrastructure.

The direct effects on the body include perception effects such as tingling skin, small harmless shocks and induced currents in the body that may cause adverse effect.

12.2.2 Magnetic Fields

Magnetic fields are created when an electric current flows, the greater the current the stronger the magnetic field. Certain items of equipment [NMR machines & MRI scanners] used within the University intentionally produce very strong magnetic fields. These may induce much larger currents in the body than electric fields and can interfere with the functions of the nervous system and light flashes may be noticed in the eye.

At frequencies in excess of 10MHz heating effects can occur and in excess of 100MHz these can lead to adverse health effects.

There are a number of indirect effects that can occur including:

      • Movement (potentially violent) of ferrous metal objects in the field.
      • Spark discharge.
      • Heating and interference with pacemakers, metallic implants, etc.

The door to any room containing a powerful magnetic source should have a warning sign indicating the hazard and access should be restricted whilst the magnet is in operation.

12.3 Radiowaves

12.3.1 Radiowaves

Radiowaves are made up of both electric and magnetic fields and are the basis for telecommunication and broadcasting systems. Antennas radiate or receive radio signals. Those that irradiate can do so in all directions for broadcasts or in narrow beams for point to point communications.

The strength of field is dependent on:

      • The total radiated power (the higher the power the stronger the field).
      • Radiation pattern (narrow beams contain stronger fields).
      • Distance from the antenna – as distance increases field strength decreases.

Health Effects

The only established health effects of the body absorbing radio waves are due to partial or whole body heating which could cause tissue damage or heat stress. This occurs at frequencies above 10 MHz, with the depth of penetration decreasing with increasing frequency. At lower frequencies currents could be induce which can interfere with function of nervous system.

Metal objects near high-powered transmitters can cause burns if touched.

The current evidence for an association between exposure to electromagnetic fields and cancer is weak and no biological mechanisms have been established for such an effect. It would however be prudent to minimise exposure to the lowest practicable level whilst working with or near sources of radiowaves.

12.3.2 Mobile Phones

These convert sound into radiowaves for transmission or reception. Handsets are used close to the body and the head of the user will absorb some of the waves. There is no evidence that this has detrimental effect but applying precautionary principles and limiting use is advised. The use of hand-held mobile phones whilst driving is prohibited (See Section 6.34)

12.3.3 Microwaves

Microwaves are radio waves and are emitted by certain types of equipment such as open-ended wave-guides and microwave ovens.

Care must be taken when using open-ended wave-guides. Burning of the skin may occur if any part of the body is placed in the path of the beam. The eyes are particularly vulnerable and in no circumstances should one look down an open-ended wave-guide when the source of microwave power is switched on. Some microwave generating equipment may also produce X-Rays.

Microwave ovens are designed to ensure that all microwave radiation is contained within the working volume. However, if damage occurs there is a possible risk to operating personnel. It is therefore necessary to arrange for periodic measurements of the radiation levels outside the oven. The Engineering Faculty Workshop has the facilities to carry out these tests and is prepared to do so on request.

Microwave ovens are also widely used in laboratories. Specific guidance on their safe use is available on the Safety Office Web Site PDF format.


Further information on the occupational exposure levels associated with the use of sources of optical and electric and magnetic fields available from the safety office or can be accessed on the Public Health England website.

 

Safety Office

Pharmacy Building - Lower Ground Floor
University Park
University of Nottingham
Nottingham, NG7 2RD

Telephone: +44 (0)115 951 3401
email: bb-safety-office@exmail.nottingham.ac.uk