Guidance Notes Concerning
THE USE OF LASERS
HEALTH AND SAFETY UNIT AUTUMN TERM 2007
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CONTENTS
INTRODUCTION 4
ADMINISTRATIVE ARRANGEMENTS 5
Laser Users/Operators 5
Supervisor/principal investigator 5
Departmental Laser Safety Officer 6
University Laser Safety Adviser 7
HAZARD CLASSIFICATION FOR LASERS 7
Example AELs 9
Maximum Permissible Exposure (MPE) 9
GENERAL SAFETY PROCEDURES 9
Laser Inventory 9
Registration of Laser Users 9
Training 9
Undergraduate work 10
Designation of Laser Areas 10
Labelling of Lasers 10
Experimental design 10
Laboratory design 11
BIOLOGICAL EFFECTS OF LASER RADIATION 12
Laser damage to the eye 12
Ultraviolet wavelengths 12
Visible and near Infra-red wavelengths 12
Infra-red wavelengths 12
Penetration of laser radiation into the eye 13
Laser damage to the skin 13
Penetration of radiation into the skin 14
Summary of laser radiation hazards 15
SAFETY PROCEDURES FOR SPECIFIC CLASSES OF LASER 15
RISK ASSESSMENT AND SYSTEM OF WORK 18
Optical hazards 18
Non-optical hazards 18
Assessing Risk 19
Risk control measures 19
Record of Assessment 20
Review 20
PERSONAL PROTECTIVE EQUIPMENT 20
Protective eyewear 20
Other protective equipment 21
ACCIDENTAL EXPOSURES AND EMERGENCY EYE EXAMINATIONS 21
LASER POINTERS 22
CONCLUSIONS 23
LASERS FOR DISPLAY PURPOSES 24
LASER SIGNS AND LABELS 25
Designated Laser Areas 25
Laser Labels 25
Aperture Labels for Class 3R, Class 3B & Class 4 lasers 28
Radiation Output and Standards Information 29
FORMS 30
SUMMARY OF WARNINGS & PROTECTIVE CONTROL MEASURES 30
LASER SURVEY FORM 31
LASER INVENTORY 33
REGISTRATION FORM FOR LASER USERS 34
USE OF CLASS 1M, 2M,2 AND 3R LASERS – HAZARD & RISK ASSESSMENT 35
USE OF CLASS 3B & 4 LASERS – HAZARD & RISK SSESSMENT 37
SYSTEM OF WORK FOR LASERS 41
EMERGENCY PROCEDURE FOR EXPOSURE TO CLASS 3B OR 4 LASER 47
TRAINING RECORD FORM 48
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INTRODUCTION
This Guidance is intended to be used as a reference document for all users of lasers within Manchester Metropolitan University and applies to both employees and students. The guidance draws from a number of reference documents including the relevant British Standard series of documents BS EN 60825 and associated amendments, and the AURPO Guidance on the safe use of lasers in education and research.
This document forms the basis of Laser Safety Management in the University and is a general guidance to good practice and assistance in the identification of hazards, risk assessment and appropriate control measures associated with the use of lasers as required by the Health and Safety at Work Act.
The current classification for lasers (implemented in 2001) is used which is based on seven classes of laser (1, 1M, 2, 2M, 3R, 3B and 4). The Safety of laser products is covered by British Standards BS EN 60825 which is based upon the corresponding International Electrotechnical Commission’s 60825 document. Of particular importance to laser users is the Technical Report PD IEC TR 60825-14 a detailed user’s guide.
ADMINISTRATIVE ARRANGEMENTS
The responsibilities of those working with or involved with laser activities in the University are as follows:
Laser Users/Operators
Laser Users/Operators have the following responsibilities:
· to observe Local Rules and Systems of Work applicable to the lasers that will be used and follow the guidance of supervisors and the Departmental Laser Safety Officer.
· to keep the supervisor fully informed of any proposal to depart from established safety procedure.
· not to leave a laser experiment running unattended unless a risk assessment has established that it is safe to do so.
· for their own safety and that of others who may be affected by their acts or omissions.
· When working with Class 3B and Class 4 lasers where there is a possibility of stray laser beams that could damage eyesight, the appropriate laser eyewear must be worn.
Supervisor/principal investigator
Research Supervisors have duty delegated to them from the Head of Department, to provide “such supervision as is necessary” to ensure the safety of all the students for whom they responsible. This includes all postgraduate and undergraduate students working with lasers. Supervisors also have responsibility for the following:
· All work involving hazardous lasers must be covered by risk assessments and where appropriate written Systems of Work and protocols.
· There should be procedures in place to ensure lasers and any associated hazardous materials are disposed of properly.
· The Supervisor should ensure that their laser users/operators are adequately trained and supervised.
· New lasers must be registered with the University Laser Safety Adviser (using the Laser Inventory form) with the exception of laser pointers and embedded lasers e.g. CD/DVD players and laser printers.
· Users of Class 3R, 3B, 4 and modified 1M and 2M lasers must be registered with the University Laser Safety Adviser (using the Registration Form For Laser Users).
· Notifying the University Laser Safety Adviser of any accident involving lasers.
Departmental Laser Safety Officer
The Departmental Laser Safety Officer plays a fundamental role in supporting that the University complies with the requirements of the Health and Safety at Work Act and the Management of Health and Safety at Work Regulations. He or she should be directly involved with the Department’s work with lasers in order to allow them to exercise sufficient supervisory authority. It is recognised that in some departments the DLSA may not be the immediate supervisor overseeing the work with lasers. In these cases the Supervisor/principal investigator takes on these duties.
The functions of the DLSO will include:
· The promotion of awareness by all persons who use Lasers within the Department to which the DLSO is assigned of any potential hazards.
· Drafting and reviewing of Local Rules/Systems of work and observing that they are applied in the appropriate areas.
· Drafting and reviewing Risk Assessments for work being carried out with lasers.
· To monitor that all users have attended or are booked to attend an appropriate Laser Safety training course.
· To restrict or stop any laser activity that does not comply with the local rules/System of Work.
· To keep a record of all users working with lasers. Users of Class 3R, 3B, 4 and modified 1M and 2M lasers must be registered with the University Laser Safety Adviser (using the Registration Form For Laser Users).
· To inform the University Laser Safety Adviser (ULSA) of details of any new lasers. New lasers must be registered with the University Laser Safety Adviser (using the Laser Inventory form) with the exception of laser pointers and embedded lasers e.g. CD/DVD players and laser printers.
· To inform the Laser Safety Adviser of any new or significantly different activities involving lasers.
· The bringing to the immediate attention of the Health and Safety Unit of any ‘incident’ involving lasers
In addition to the above the DLSO will undertake to attend appropriate training in order to carry the above duties effectively.
University Laser Safety Adviser
The University Laser Safety Adviser has responsibility for the administration and auditing of systems of control relating to Laser Safety in order to ensure compliance with the Health and Safety at W ork Act and provide advice and assistance in order to implement the requirements of BS EN 60825.
The University Laser Safety Adviser will conduct routine inspections of laboratories in which laser work is undertaken and provide information and advice. In addition the ULSA has the following responsibilities:
· To provide assistance in evaluating and controlling hazards
· To maintain a register of lasers and users
· To co-ordinate laser safety training of laser users, supervisors/principal investigators and Departmental Laser Safety Officers.
· To participate in any accident investigations involving lasers.
· To restrict or stop any laser activity that does not comply with the Health and Safety at Work Act and BS EN 60825
· To inform all Departmental Laser Safety Officers of any change in existing or new legislation applicable to the use of lasers.
· To provide guidance on the safe use of lasers.
HAZARD CLASSIFICATION FOR LASERS
Lasers produce electromagnetic radiation in the wavelength range 100nm (ultraviolet) to 1mm (infrared) which includes the visible range 400nm-700nm. The output from a laser may be continuous (CW) or pulsed which produce short bursts of radiation. Because of the wide ranges of wavelength, energy and pulse characteristics of laser beams, the hazards arising from their use varies widely.
Lasers are grouped into seven categories depending on the potential to cause harm. Accessible Emission Levels (AELs) have been determined for each class of laser. The AEL depends on the wavelength, exposure duration and the viewing conditions and specifies the maximum output within each laser class.
Laser classes are as follows:
Class 1: Lasers that are safe under reasonably foreseeable conditions either because of the laser’s low emission or because of engineering design such that it is totally enclosed and access to higher levels is not possible during normal operation e.g. CD/DVD player or a laser printer. NB If access panels on a totally enclosed system are removed then the laser product is no longer a Class 1 laser product and the precautions applicable to the embedded laser must be applied.
Class 1M: Laser products emitting in the wavelength range between 302.5nm and 4000nm whose total output is in excess of a Class 1 laser but, because of their diverging beams or low power density, do not pose a hazard under reasonably foreseeable conditions. However, they may be hazardous to the eyes under the following conditions:
a) With a diverging beam if optics are placed within 100mm of the source to collimate/concentrate the beam.
b) With a large diameter collimated beam where optics are used to increase the proportion of the beam entering the eye e.g. binoculars or telescope.
Class 2: Lasers emitting in the visible wavelength region between 400nm and 700nm and whose output is less than the appropriate AEL. Safe for accidental viewing as protection of the eyes is provided by the aversion response (blinking and/or moving the head).
Class 2M: Laser products emitting in the visible wavelength region between 400nm and 700nm whose total output is in excess of a Class 2 laser but, because of their diverging beams or low power density, are safe for accidental viewing under reasonably foreseeable conditions. However, they may be hazardous to the eyes under the following conditions:
a) With a diverging beam if optics are placed within 100mm of the source to collimate/concentrate the beam.
b) With a large diameter collimated beam where optics are used to increase the proportion of the beam entering the eye e.g. binoculars or telescope.
Class 3R: Lasers emitting in the wavelength range 302.5nm to 1mm where direct intrabeam viewing is potentially hazardous but the risk is lower than for Class 3B lasers. The AEL is below five times the Class 2 AEL in the visible region (400nm-700nm) and below five times the Class 1 AEL for all other wavelengths.
Class 3B: Lasers in both the visible and invisible range of wavelengths. Direct intrabeam viewing near (i.e. within the Nominal Ocular Hazard Distance where the radiant exposure will exceed the Maximum Permitted Exposure limit) is always hazardous. Viewing diffuse reflections is normally safe provided the eye is no closer than 13cm from the diffusing surface and the exposure duration is less than 10 seconds. Output levels must be less than the appropriate AEL for Class 3B devices.
Class 4: High power lasers from which direct beam or reflected beam viewing is always hazardous. Likely to cause both eye and skin injury. Environmental damage (fire and hazardous fumes) is also a serious possibility. Class 4 laser use requires extreme caution.
Example AELs
The AELs for Helium-Neon lasers emitting a continuous narrow beam at 633nm are as follows:
Class 1 and 1M 0.39 mW
Class 2 and 2M 1.00 mW
Class 3R 5.00 mW
Class 4 500.00 mW
The above limits will also apply to other narrow beam visible CW lasers except for Class 1 and 1M devices where there further restrictions apply to wavelengths below 500nm. For full details of restrictions see BS EN 60825-1.
Maximum Permissible Exposure (MPE)
The Maximum Permissible Exposure (MPE) is the level of radiation below which no adverse effects to the eye and skin should occur. There is a safety factor incorporated into the MPEs to take account of individual variations in sensitivity to laser radiation. MPE levels are specified in BS EN 60825-1 and in particular in – Safety of Laser Products – Part 14: A user’s guide, PD IEC TR 60825-14:2004. Planned ocular exposure to lasers should not exceed the MPE.
GENERAL SAFETY PROCEDURES
Laser Inventory
All Class 3R, 3B and Class 4 lasers should be identified and recorded on the Laser Inventory Form, a copy of which should be sent to the University Laser Safety Adviser. In addition Class 1M, 2M and Class 2 lasers should also be recorded except for laser pointers and embedded lasers in products such as laser printers and CD/DVD players. It is not necessary to register low powered Class 1 devices.
Registration of Laser Users
All persons intending to work with lasers except for inherently safe Class 1 and Class 2 devices or embedded lasers in products such as laser printers and CD/DVD players, should register with the University Laser Safety Adviser using the Registration form for Laser Users.
Training
Persons intending to use Class 3R, 3B and Class 4 lasers should attend training before commencing any laser work and should also be familiar with System of Work for the lasers they intend to use. Training in the use of individual lasers is the responsibility of the Student/Research Supervisor and a record of this training should be made. The Training Record for Authorised Laser Users must be filled in and a copy sent to the University Laser Safety Adviser. Laser Safety Training Sessions can be arranged by contacting the University Laser Safety Adviser.
Undergraduate work
Wherever possible undergraduate work should be restricted to Class 1, 1M, 2, 2M or visible 3R lasers. For class experiments it is important to introduce students to good safety practice and a written system of work/local rules should be drawn up and posted in the laboratory. In addition, clear written instructions should be provided for each student experiment.