Safe use of lasers in research and teaching:

Transcription

1 Health and Safety Procedure HSP 003 Safe use of lasers in research and teaching: Part 2 Rules for laser workers and guidance on safe working practices HSP.003/Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 1

2 Safety, Health and Environment Unit Title Health and Safety Procedure Safe Use of Lasers in Research and teaching. Part 2 Rules for laser workers and guidance on safe working practices Reference Number HSP 003 DOCUMENT HISTORY Issue Date Details Draft Draft to be submitted to SHEEC Draft Amendments following Laser Safety Adviser s comments Sept 2006 Amendment section 3 March 2010 Review by Laser Safety Adviser and reference to Control of Artificial Optical Radiation at Work Regulations April Amended by Ray Allard, SHE Unit Author M. Salmon Signature Date Reviewer J. Cheney Signature Date Authorised by Prof. P. Davies Chair of SHEEC Signature Date Issued by Safety, Health and Environment Unit Signature Date HSP.003/Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 2

3 Contents Page 1. Introduction 4 2. Procedure objectives 4 3. Management Responsibilities 4 4. Laser worker Responsibilities Laser worker rules Registration of personnel Undergraduate experiments and lecture demonstrations Classification of lasers Registration of lasers Medical supervision Emergency eye examination accidental exposure Laser pointers 6 5. Availability of safety advice 6 6. Training requirements 7 7. Further information 7 Appendices 1. Risk assessment of the work 8 2. Laser registration form 9 3. Laser worker registration form Guidance on safe use of laser pointers Emergency procedure form Guidance on laser safety and laser classifications 13 HSP.003/Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 3

4 1. Introduction Laser work is covered by the general requirements of the Health and Safety at Work etc. Act 1974 and the Management of Health and Safety at Work Regulations In addition, the Control of Artificial Optical Radiation at Work Regulations, effective April 2010 (European Artificial Optical Radiation Directive 2006/25/EC) lay down minimum health and safety requirements regarding exposure of workers to risks arising from optical radiation. These regulations restate the requirement for risk assessment, introducing controls to eliminate or reduce risks, training in safe use and where appropriate consideration of health surveillance. Importantly for laser beams use these regulations introduce the legal adoption of defined Exposure Limit Values (ELVs) to which laser workers must not be exposed. Exposure Limit Values for Lasers are found in the Directive. Thus, management has a responsibility to ensure that work with lasers is carried out safely and all users have a duty to protect both themselves and others from the risks involved. These are not just optical risks but associated ones from, for example, electrical supplies, cryogenic liquids or chemical dyes. This document is for the attention of laser workers; Part 1 details the policy and procedures for its implementation and is issued to those with managerial responsibilities for the use of lasers. This revision has been produced following a review of guidance available and recent changes made (IEC Amendment 2 Jan 2001) to the laser classification system. The previous classification system, which was based on five classes (1, 2, 3A, 3B & 4), has been replaced by a new system of seven classes (1, 1M, 2, 2M, 3R, 3B & 4). It applies to all lasers, except Class 1, in the University and includes all homemade lasers, laser pointers, those bought outside and those brought to the University from other establishments even for short periods. This document replaces the previous document of the same name reference lasers Pt2 4/2000 which should be destroyed. University Policy on lasers is detailed in Health and Safety Procedure HSP Procedure Objectives The objectives of this procedure are: To reduce, so far as is reasonably practicable, the exposure of staff, students and other persons to non-ionising radiations and other hazards associated with the use of lasers. To comply with legal requirements, in particular the Health and Safety at Work etc. Act 1974 to ensure that employees and others are not put at risk, The Management of Health and Safety at Work Regulations 1999 in regard to the management of the risks associated with laser work. and the Control of Artificial Optical Radiation at Work Regulations, April 2010 To ensure that all work with lasers conforms to current European Standards. To ensure that all reasonable steps have been taken to minimise the risk of the relative laser Exposure Limit Values being exceeded 3. Management Responsibilities Management responsibilities for lasers are detailed in Health and Safety Procedure HSP 002. Day-to-day responsibility for the safety of laser work and workers rests with the person in charge of the work (the Supervisor). HSP.003/Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 4

5 Departmental Laser Safety Officers (DLSOs) have been appointed to ensure, on behalf of their Head of School/Department, that the University s policy and rules controlling work with lasers are fully implemented. The names of current DLSOs are available from the appropriate school or department. 4. Laser worker Responsibilities 4.1 Laser workers are required to: carry out a risk assessment in collaboration with their supervisor; receive and abide by appropriate instruction and training from their School/Department; follow the procedures devised for safe performance of the work; report immediately to their supervisor any accident or serious potential accident involving a laser. or any personal reason that might affect their or anyone else s safety 4.2 Registration of personnel All people intending to work with Classes 3R, 3B or 4 lasers must register with the Safety, Health and Environment Unit via their DLSO. Each worker must complete, and return to the Safety, Health and Environment Unit, form LAS/2 (2000) [shown in Appendix 3; copies available from the Safety, Health and Environment Unit]. Upon receipt of the completed application form, the Safety, Health and Environment Unit will complete the registration process by issuing a numbered certificate. No practical work with Class 3 or Class 4 lasers must start until this registration process has been completed. 4.3 Undergraduate experiments and lecture demonstrations If reasonably practicable, undergraduate work and lecture demonstrations will be confined to the use of Classes 1, 2 and 3R lasers. Students involved in project work and expected to use Class 3 or Class 4 lasers will be treated as laser workers and required to register with the Safety, Health and Environment Unit (see Section 4.2). 4.4 Classification of lasers All lasers must be classified according to the degree of hazard they present, as detailed in BS EN Appropriate labelling is important and the guidance given in the CVCP booklet should be followed. A stock of labels is maintained in the Safety, Health and Environment Unit (see Appendix 6 for guidance on classification of lasers). Class 3B and Class 4 lasers may only be used inside designated laser areas. Access to such areas must be controlled and appropriate warning signs displayed outside the room. 4.5 Registration of lasers All lasers except those falling within the inherently safe Class 1 definition must be registered with the Safety, Health and Environment Unit; this requirement covers lasers built in the laboratory as well as commercially-obtained ones. Form LAS/1 (2000) (shown in Appendix 2) is available from the Safety, Health and Environment Unit for this purpose. 4.6 Medical supervision Eye examinations for laser users are not now recommended as a part of a safety programme. The value of routine examinations for Class 3B/4 laser users has been reviewed; it was agreed that routine examinations are of little value. HSP.003/Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 5

6 Where there has been an apparent or suspected ocular exposure a medical examination by a qualified specialist needs to be carried out. This is dealt with in the next section. 4.7 Emergency Eye Examinations Accidental Exposure In the event of an accident or incident involving suspected injury to the eye(s), an emergency examination should be carried out as soon as possible and within 24 hours.. This can be arranged by contacting the Ophthalmology Emergency Service at William Harvey Hospital by telephoning , or by taking the injured person to: The Casualty Unit, William Harvey Hospital, Ashford, Kent. Schools/Departments must have suitable arrangements in place and must ensure that all persons working with Class 3/4 lasers are aware of the action to take in the event of an accident/incident. Each Class 3/4 laser is required to have a card or proforma that can be taken with the casualty to Hospital (a sample proforma is included in Appendix 5). Where an emergency eye examination is required, the University Laser Safety Adviser and School/Departmental Laser Supervisor/Officer will carry out a detailed investigation of the accident/incident. Any accident involving the use of lasers, whether or not harm or damage resulted, must be reported forthwith to the Supervisor. An accident report form will then be completed by the Supervisor following an investigation; depending upon the severity of the incident, the DLSO and/or the LSA may become involved. 4.8 Laser Pointers Lasers are commonly available and some are for presentation purposes as pointers. These laser pointers are classified at a level above Class 1 and therefore in some circumstances can cause harm, particularly by staring into the beam. Lasers pointer use must be restricted to the following: In unsupervised areas only class 1 and 2 lasers pointers can be used (the normal eye s blink response affords protection); In supervised areas (i.e. when used by a professional lecturer) class 3R pointers may also be used if the reason is justified Class 3B laser pointers must not be used. Where laser pointers are used instructions on their safe use should be readily available; Appendix 4 is an example of the instructions which should be provided. In the event that the presenter or member of the audience etc. suffers an exposure from the laser beam then the emergency procedures outlined in section 4.7 must be followed. 5. Availability of safety advice The main requirements for the radiation safety of laser products are covered by BS EN edition 2. The Committee of Vice-Chancellors and Principals (CVCP) has published a safety book Safety in Universities. Notes of Guidance, Part 2:1 Lasers, revised edition and since superseded by the AURPO Guidance Note no , on the Safe Use of Lasers in Education and Research.. In addition the Control of Artificial Optical Radiation at Work Regulations, effective April 2010 (European Artificial Optical Radiation Directive 2006/25/EC) lays down minimum health and safety requirements regarding exposure of workers to risks arising from optical radiation. Importantly for laser beams use these regulations introduce the legal adoption of defined Exposure Limit Values (ELVs) to which laser workers must not be exposed. Exposure Limit Values for Lasers are found in the Directive. Copies of both documents are held by the DLSOs and in the Safety, Health and Environment Unit (guidance on the salient points of the CVCP document can be found in appendix 6). The DLSOs should HSP.003/Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 6

7 be consulted in the first instance with reference to the Safety, Health and Environment Unit and University Laser Safety Adviser if necessary. 6. Training requirements 1. DLSOs and Supervisors of laser workers must attend a laser safety training course approved by the Safety, Health and Environment Unit prior to undertaking their duties; 2. Any individual working with lasers must receive adequate instruction in laser safety, the local rules and safe operation of the specific lasers being used and the requirements of this procedure before working with lasers. 7. Further Information The Control of Artificial Optical Radiation at Work Regulations, 2010 (European Artificial Optical Radiation Directive 2006/25/EC) British Standard EN :edition Safety of laser products, Part 1: Equipment classification, requirements. British Standard EN : 2004 Safety of laser products, Part 2: Safety of optical fibre communications systems. PD IEC TR BS :2004 Safety of laser products A users guide (originally included in Part 1 of the British Standard) British Standard EN 207: 1999 Filters and Equipment used for Personal Eye-Protection Against Laser Radiation. British Standard En 208: 1999 Personal Eye-Protection Used for Adjustment Work on Lasers and Laser Systems. CVCP Safety in Universities: Notes of Guidance Part 2:1 Lasers Revised CVCP October 1992 ISBN AURPO Guidance Note no , on the Safe Use of Lasers in Education and Research Hazards of Optical Radiation. A Guide to sources, uses and safety. A F McKinlay, F Harlen and M J Whillock ISBN INDG224 Controlling The Radiation Safety Of Display Laser Installations The radiation safety of lasers used for display purposes - Health & Safety Executive publication HS (G) ISBN The use of lasers in the Workplace. A practical guide. International Labour Office, Geneva. Occupational Safety and Health Series No ISBN The Health Protection Agency and the Health and Safety Executive websites include information about laser hazards HSP.003/Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 7

8 APPENDIX 1 Risk assessment of the work All work with lasers must be risk-assessed before the work starts. The assessment should be carried out by the worker and his/her supervisor, if necessary in consultation with the DLSO and the Laser Safety Adviser. The assessment, which must be recorded, should include:- 1. a brief description of the work planned; 2. the name(s) of the person(s) authorised to use the laser or to align or maintain the equipment; 3. a description of the laser including its class, power / energy output, pulse/cw characteristics; 4. a note of the hazards associated with the laser set-up to be used, e.g. a. capacity to injure eye or skin; b. fire in the target or other objects irradiated; c. noise such as impulse noise from pulsed lasers, d. toxic by-products such as those resulting from irradiation or vaporisation of target materials; e. toxic chemicals used either in the laser, such as a dye-laser, or in associated equipment; f. electrical hazards from high voltage supplies, from capacitor banks used with pulsed lasers, from incorrectly used leads and adaptors; g. water in the presence of electrical supplies; h. use of cryogenic materials; [this list is not exhaustive] 5. an evaluation of the risk of harm from the hazards by considering the capability to injure (i.e. human access), the environment of use and the level of training of operators; for class 3B and 4 lasers this evaluation must include an analysis of the maximum potential laser output in relation to the ELV Exposure Limit Value (Maximum Permissible Exposure) (MPE) and Nominal Ocular Hazard Distance (NOHD) (as defined by BS EN ). In relation to laser output adjusted as part of experimentation, risk assessment should consider the worst case scenario. 6. the appropriate measures required to control the risks and provide safe working; N.B. Guidance on control measures is given in the CVCP booklet and in BS EN and AURPO Guidance Note no , Safe Use of Lasers in Education and Research which are held by the DLSOs and in Notes on Protection against Laser Radiation in the Laboratory by D. Hughes, HHSC Handbook No. 10, 1992, a copy of which is held in the Safety, Health and Environment Unit. 7. the signatures of the assessors and the dates of the assessment and planned routine re-assessment. HSP.003/Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 8

9 APPENDIX 2 Safety, Health and Environment Unit Registration of Lasers School/Department: Person responsible: Building and room where used:.... Make, model no. and serial no.:.... (or other means of identification) Type of laser (He-Ne, Ruby, etc.):... Class of laser:.... Mode of operation (CW, pulsed, Q-switched, etc.):.... For CW lasers: Maximum power output:.... For pulsed and Q-switched lasers: Pulse duration:... Pulse repetition frequency:... Maximum joules per pulse:.... Wavelengths used:... Beam diameter:... Beam divergence (if known):.... Brief description of use: Details of eyewear provided Signature of person responsible:.. Date:. Please return completed form to the Safety, Health and Environment Unit, Room Dg.6, Keynes College Form No. LAS/1 (2000) HSP.003/Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 9

10 APPENDIX 3 Registration of persons using lasers or exposed to laser radiation in the course of their work Surname [block capitals]: First names [in full]: School/Department: Status: Supervisor: Date of start of work with lasers: Brief details of work or exposure: Laser(s) to be used and their classification (s): Location of lasers: Experiments to be performed: Risk assessment completed Yes No Laser safety video viewed Yes No Work covered by Scheme of Work Yes No Signature of Supervisor: Date: Declaration by worker: I have received, read and understood a copy of Safe use of lasers in teaching and research: Part 2 Rules for laser workers and guidance on safe working practices and will abide by the rules and advice set out therein. Signed: Date: Please return completed form to the Safety, Health and Environment Unit, Room Dg.6, Keynes College Form No. LAS/2 (2000) Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 10

11 APPENDIX 4 THE SAFE USE OF LASER POINTERS The University Health and Safety Procedure on the Safe Use of Lasers in Research and Teaching lays out the requirements for the control of hazards associated with lasers. Lasers are commonly available and some are used for presentation purposes as pointers. Power outputs of laser pointers can vary. Class 1 laser systems are normally safe. Class 2 and 3R systems are not hazardous under certain conditions, however they can cause harm to the eyes particularly if the beam is stared into. Normally the eye's blink reflex affords protection to short duration accidental exposure to Class 2 and 3R lasers. Class 1 or Class 2 laser pointers are the recommended choice where a laser pointer is necessary. Class 3B laser pointers must not be used. Laser pointers should only be used as a pointing device and appropriately securely stored when not in use. Persons who use laser pointers should ensure that they are aware of potential hazards and they should comply with the basic instructions below. Instructions for use When operating laser pointers, users must ensure that they use these in a safe manner and do not expose themselves or others to the beam. Laser pointers are not to be modified in any way. DO: DO NOT: Follow the manufacturer's safety instructions Take care when operating the laser pointer Keep the on button depressed only when necessary Do not keep the 'on' button depressed when not pointing at the screen Do not point at or towards the audience Do not point at mirrored surfaces Never look into the laser aperture Never look directly or stare into the beam/beam aperture when on Never allow unauthorised use, especially by children Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 11

12 APPENDIX 5 EMERGENCY PROCEDURE LASER HAZARD EXPOSURE to Class 3/4 laser Contact the Ophthalmology Emergency Service, William Harvey Hospital on or report to the Casualty Unit, William Harvey Hospital, Ashford Kent as soon as possible and within 24 hours of the incident. Do not drive yourself; get a friend or colleague to take you. Out of hours: Use an internal phone and call 3333 i. State Building and School/Department ii. Location and nature of incident/accident iii. Request ambulance to take the casualty to the Casualty Unit, William Harvey Hospital iv. Take the card below to the Hospital EMERGENCY OPHTHALMIC EXAMINATION LASER Exposure Report to: Casualty Unit William Harvey Hospital Ashford Kent TN24 0LZ Tel: LASER DETAILS: i. Type: Continuous Wave / Pulsed* ii. Wavelength: nm iii. Power Output (CW):. or Pulse Energy, Duration, and Rate (pulsed):. iv. Laser Classification:. THE UNIVERSITY OF KENT School/Department. EXPOSURE DETAILS: i. Circumstances of accident/injury: ii. Time/Date of Injury iii. Eye affected: Left/Right/Both* iv. Were protective goggles being worn? Yes/No* * delete as appropriate REPORT ACCIDENT/INCIDENT to THE SAFETY, HEALTH AND ENVIRONMENT UNIT on Ext [voic outside normal hours] All accidents and incidents, whether involving an emergency examination or not, must be reported promptly to the Safety, Health and Environment Unit using the current University Accident Report Form. The Departmental Laser Safety Officer, in conjunction with the Supervisor and University Laser Safety Adviser/Safety, Health and Environment Unit if appropriate, must also carry out a detailed investigation of the accident. A copy of this report together with results of the ophthalmologic examination will be referred to the Ophthalmology Unit, William Harvey Hospital, Ashford, Kent TN24 0LZ. Any serious injury or 3-day absence from work has to be reported to the Health and Safety Executive under 'The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995'. Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 12

13 APPENDIX 6 Guidance on laser safe working practices and laser classifications 1. Summary of guidance from CVCP document The extensive advice given in the CVCP booklet and in BS 60825:1 should be followed. Copies of these documents are held by each DLSO. A few of the salient points from the documents are listed here. Nearly all lasers will give rise to energy or power densities in their direct beam which are greater than the Maximum Permissible Exposure Levels (MPEs) recommended for the cornea. In many cases reflected, refracted or scattered radiation will also exceed these levels. To ensure that people are not exposed to laser radiation in excess of MPEs, a suitable combination of engineering and administrative controls and personal protective equipment is required. The prime controls are engineering ones, such as bolting down the laser so that the beam cannot be knocked accidentally out of alignment, enclosing all beam paths and using fail-safe interlocks to prevent unauthorised access to the beam. Practically, it is usually necessary to have administrative controls as well. Thus all equipment must be properly labelled so that workers are aware of the hazards involved; safe systems of work need to be devised this is particularly important for non-standard operations such as alignment, servicing and maintenance; adequate training and instruction and appropriate supervision must be given. Ideally, an appropriate combination of engineering and administrative controls should provide all that is necessary to achieve safe operation. However, the risk assessment may indicate that, even with these in place, there is still the possibility of people being exposed to radiation in excess of the MPEs. In these circumstances, specially approved laser safety goggles and/or protective clothing may be necessary. 2. Hazard classification for lasers Lasers produce electromagnetic radiation at wavelengths extending from 180nm in the ultra-violet, through the visible ( nm), and the near infrared ( nm), to the far infrared (1400nm - 1mm). Thus, the light emitted can be either visible or invisible. Lasers can be operated in a number of different modes. Some lasers produce a continuous output and are known as continuous wave or CW lasers. The power outputs of CW lasers are usually expressed in terms of watts (W). Others operate in a pulsed mode producing short bursts of radiation. The power of the laser output can vary from less than 1mW to many watts in some CW devices. The energy output of pulsed lasers is generally expressed in joules (J) per pulse. Because of the wide ranges possible for the wavelength, energy content and pulse characteristics of a laser beam, the hazards arising in its use vary widely. It is impossible to regard lasers as a single group to which common safety limits can apply. A system of laser classification is used to indicate the level of laser hazard; this has been derived from the Maximum Permissible Exposure Levels (MPEL). The previous classification system, which was based on five classes (1, 2, 3A, 3B & 4), has been replaced with a new system of seven classes (1, 1M, 2, 2M, 3R, 3B & 4) and these are described below. Class 1: Lasers that are safe under reasonably foreseeable conditions of operation, either because of the inherently low emission of the laser itself, or because of its engineering design such that it is totally enclosed and human access to higher levels is not possible under normal operation. Class 1M: Lasers emitting in the wavelength range from nm to nm which are safe under reasonably foreseeable conditions of operation, but may be hazardous if the user employs optics within the beam. This class applies to: Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 13

14 a) diverging beams if the user places optical components within 100 mm from the source to concentrate (collimate) the beam; or b) a collimated beam with a diameter larger than the diameter specified in the published standard for the measurements of irradiance and radiant exposure. Class 2: Lasers that emit visible radiation in the wavelength range from 400 nm to 700 nm where eye protection is normally afforded by aversion responses, including the blink reflex. This reaction may be expected to provide adequate protection under reasonably foreseeable conditions of operation including the use of optical instruments for intrabeam viewing. Class 2M: Lasers that emit visible radiation in the wavelength range from 400 nm to 700 nm where eye protection is normally afforded by aversion responses including the blink reflex. However, viewing of the output may be more hazardous if the user employs optics within the beam. This class applies to: a) diverging beams where the user places optical components within 100 mm from the source to concentrate (collimate) the beam, or b) a collimated beam with a diameter larger than the diameter specified in the published standard for the measurements of irradiance and radiant exposure. Class 3R: Lasers that emit in the wavelength range from nm to 1 mm where direct intrabeam viewing is potentially hazardous but the risk is lower than for Class 3B lasers, and fewer manufacturing requirements and control measures for the user apply than for Class 3B lasers. The accessible emission limit is within five times the Accessible Emission Limit (AEL) of Class 2 in the visible wavelength range from 400 nm to 700 nm and within five times the AEL of Class 1 for other wavelengths. Class 3B: Lasers that are normally hazardous when direct intrabeam exposure occurs (i.e. within the Nominal Ocular Hazard Distance, which is the distance at which the beam irradiance or radiant exposure equals the appropriate MPE). Viewing diffuse reflections is normally safe. Class 4: Lasers that are also capable of producing hazardous diffuse reflections. They may cause skin injuries and could also constitute a fire hazard. Their use requires extreme caution. Note: IEC Amendment 2, which includes the new classification system, was published in January 2001 effective from 1st January However, manufacturers can still use the previous classification scheme until the 1st January Laser systems that are already classified and labelled, within the University, do not have to be re-classified for the present time. There are no major differences between schemes to the classification of both Class 3B and 4 lasers systems. Details of the previous classification system used can be found in the CVCP Notes of Guidance, Part 2:1 Lasers Revised Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 14

15 3. Synopsis of the control measures necessary for each class of laser Precautions Class 1* Class 2 Class R (3A) Class 3B Class 4 1. Remote interlock 2. Key Control 3. Emission Indication 4. Beam Shutter 5. Beam Stop 6. Beam Level 7. Beam Enclosure 8. Eye Protection 9. Protective Clothing 10. Training 11. Laser Labels 12. Door Signs * Note that where engineering design is such that the laser is totally enclosed and therefore classified at a lower level, it may require additional controls such as 2,3,4,5,7 and 10 in the table [subject to risk assessment] Except Class 3B lasers with not more than 5 times the AEL of Class 2 in the wavelength range 400nm to 700nm 1. Remote Interlock interlocked to the door or the enclosure required for all Class 4 lasers and the higher powered Class 3B 2. Key Control all Class 3B and Class 4 lasers should be provided with this to ensure that only authorised personnel use the laser 3. Emission Indicator all Class 3B and Class 4 lasers should have this, may also be sited outside the laboratory to give warning of laser in use 4. Beam Shutter should be provided for all Class 3B and Class 4 lasers 5. Beam Stop for Class 2 and above to ensure that the laser is terminated within the confines of the laser bench or experimental area 6. Beam Level avoid experimental set up that allows beam at eye level 7. Beam Enclosure needed to guard against specular reflection from Class 3B and Class 4 lasers can mean anything from screening the experimental area or beam up to a total enclosure 8. Eye Protection required for Class 3B and Class 4 lasers Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 15

16 9. Protective Clothing mainly required for Class 4 lasers 10. Training all people working with Class 3R lasers and above should receive training 11. Laser Labels all lasers should display the appropriate labels 12. Door Signs required for all laser areas where Class 3R lasers or above are used If all the engineering features required by items 1-7 are not in place, (particularly item 7), then appropriate administrative controls should be drawn up to ensure the safe use of the laser. These should be detailed in the written scheme of work. 4. Indirect hazards Indirect hazards associated with lasers must not be forgotten. Care must be taken to avoid risks from any electrical and water supplies required. Forced ventilation of the work area may be necessary if atmospheric contamination caused by vaporisation of the target, from gases flowing in the laser systems or from cryogenic coolants is likely to arise. Protection may be needed from collateral radiation (u.v., visible or i.r.) arising from associated flash lamps or discharge tubes and pump sources. Safety, Health and Environment Unit/MLS/ RevSep06/RevApr10 16