OFTC LASER SAFETY PROGRAM

Transcription

1 OFTC LASER SAFETY PROGRAM POLICIES AND PROCEDURES FOR LASER USERS OPTICAL FIBRE TECHNOLOGY CENTRE UNIVERSITY OF SYDNEY AUSTRALIA EDITION JAN 2006 BY OFTC LASER SAFETY OFFICER MARTIJN VAN EIJKELENBORG 0

2 TABLE OF CONTENTS Page POLICY AND PURPOSE 2 DEFINITIONS 3 INTRODUCTION TO LASER HAZARDS 4 RESPONSIBILITIES 7 PROCEDURES 12 CONTROL MEASURES 14 RECOMMENDED WORKING PRACTICES FOR LASER LIGHT IN OPTICAL FIBRES 17 REFERENCES and FORMS 18 1

3 POLICY AND PURPOSE The Optical Fiber Technology Centre (OFTC) Laser Safety Policy and Procedures are based on the Australian/New Zealand Standard Safety of laser products (AS/NZS :2004 and AS/NZS :2004) Under its Health and Safety Policy the University of Sydney is committed to taking every reasonable precaution for the health and safety of its employees and students. It is the objective of the Laser Safety Policies and Procedures to provide the OFTC community at the University of Sydney a framework by which to effectively control all laser hazards in accordance with the University Health and Safety Policy. The basic elements of the policy are: (a) registration of all hazardous lasers and laser systems; (b) registration and requirement for training and education of laser workers; (c) requirement for reporting accidents and incidents involving lasers; (d) provision of medical surveillance; (e) requirement for providing engineering controls; (f) requirement for providing administrative and procedural controls; (g) requirement for providing personal protective equipment; (h) requirement for inspections and assessment of the effectiveness of the program. The OFTC Laser Safety Policy applies to all lasers and laser systems at the OFTC and to all those involved with lasers at the OFTC. 2

4 DEFINITIONS LASER - A device which produces an intense, coherent, directional beam of light by stimulating electronic or molecular transitions to low energy levels. LASER is the acronym for Light Amplification by Stimulated Emission of Radiation. LASER SYSTEM - Assembly of electrical, mechanical, and optical components which includes one or more lasers. CLASS 1 LASER PRODUCT Safe, no precautions required. CLASS 1M LASER PRODUCT Safe without viewing aids. CLASS 2 LASER PRODUCT (visible wavelengths only) Safe with aversion response. Can cause eye damage if the beam is stared into for long periods of time. CLASS 2M LASER PRODUCT (visible wavelengths only) Safe with aversion response without viewing aids. Can cause eye damage if the beam is stared into for long periods of time. CLASS 3R LASER PRODUCT Low risk for visible wavelengths with aversion response and without viewing aids. Not safe outside the visible. CLASS 3B LASER PRODUCT Unsafe for eyes, generally safe for skin. Can cause biological damage to the eyes even when viewed briefly. Not a fire hazard. CLASS 4 LASER PRODUCT Unsafe for eyes and skin. Direct viewing and specular as well as diffuse reflections can cause damage to the eyes or skin. Potential fire hazard. HAZARDOUS LASER A Class 3R, Class 3B or Class 4 laser or laser system ACRONYMS HoD SO LSO DLSO LM ILU OHSRM CLA SOP Head of Department; Safety Officer; Laser Safety Officer (a person in the OFTC who is knowledgeable in the evaluation and control of laser hazards); Deputy Laser Safety Officer; Lab Manager (an individual who is in charge of a laser laboratory that houses any hazardous lasers or laser systems; Individual Laser User (an individual who operates or works in proximity to hazardous lasers and laser systems); Occupational Health and Safety Risk Management; Controlled Laser Area; Standard Operating Procedure. 3

5 INTRODUCTION TO LASER HAZARDS The hazards from laser equipment can be grouped into five categories: (a) eye hazards; (b) skin hazards; (c) electrical hazards; (d) chemical hazards; (e) miscellaneous hazards. The initial cause of any type of radiation damage to biological tissue is the absorption of energy. Such damage is familiar to anyone who has experienced sunburn. Yet the absorption of energy is a complex process that occurs at the molecular level and is dependent on the wavelength of the radiation and the characteristics of the target tissue. The degree of tissue breakdown can be related to the physical parameters of the radiating source such as the wavelength, pulse duration, beam size and the length of time exposed to that source. Emission from most lasers is unlikely to cause a direct fatality, although this effect is within the capability of some very high-power lasers. For many laser systems, however, fatality can occur through electrocution from the laser power supply. EYE HAZARDS Different parts of the eye may be injured depending upon which structure absorbs the greatest radiant energy per volume of tissue. Laser radiation in the visible and near infrared portions of the spectrum are transmitted by the forward optical structures of the eye (i.e. there is very little absorption of radiant energy) and the main absorption occurs at the retina with consequent risk of damage. On the contrary, ultraviolet and far infrared radiation is absorbed strongly at the corneal surface (by different mechanisms) and virtually no radiation penetrates into the eye. In this case the potential for damage is at the cornea. Visible-wavelength laser beams may end up focused onto the retina into an area as small as 10 microns in diameter. The minimum image size on the retina of a collimated laser beam depends upon the range at which the eye is focused and, to a lesser extent, the wavelength of the laser radiation. The typical result of a retinal injury is a blind spot or scotoma within the irradiated area. Direct viewing of a laser beam may result in a scotoma located in the fovea, the high acuity or central vision area of the retina, causing a severe visual handicap. Peripheral viewing may result in a scotoma located in the peripheral retina, which may go unnoticed for some time. Far-infrared radiation is absorbed at the outer surface (cornea) of the eye. The absorbed energy may generate sufficient heat to overwhelm the eye s natural cooling mechanisms. Ultraviolet radiation can cause damage to the cornea depending on the level of exposure. High levels may permanently damage the cornea or lens. Intermediate exposure levels cause severe but temporary cornea injury. The latter only lasts for one or two days, but can be extremely painful. 4

6 SKIN HAZARDS There is no hazard to skin from Class 1, 1M, 2, 2M and 3R lasers. When working with high-powered lasers of Class 3B or Class 4, severe injury to the skin is less likely than permanent eye damage. The levels of visible and infrared radiation required to cause injury to the skin are relatively high (at least several hundreds of watts per square metre are required), depending on the area of skin absorbing the laser radiation but also upon the wavelength, the absorption depth and exposure duration. Some Class 4 lasers at the OFTC are capable of delivering power sufficient to cause skin burn, but the normal aversion reaction when the pain is detected limits this to superficial and mostly temporary damage. The 355 nm Class 4 lasers at the OFTC, however, can cause damage to human cell DNA that can lead to skin cancer. ELECTRICAL HAZARDS Almost all laser power supplies have the potential to cause severe electrical shock. Electrical safety precautions should always be followed when using any electrical or electronic equipment and repairs or maintenance should only be carried out by authorized persons. Serious electrical hazards exist with most lasers, especially those that have been built or modified for research purposes in research laboratories. CHEMICAL HAZARDS Many of the materials required for laser operation, as well as products produced by the laser during operation or by beam interaction with target materials are potentially hazardous to operating personnel. Several laser dyes and their common solvents are toxic. Of the 150 or so dyes used (in for instance dye lasers) the cyanine and carbosyanine compounds are the most toxic, which is exacerbated by the need to dissolve these in dimethylsulfoxide (DMSO), a solvent that facilitates molecule transfer through biological membranes such as the skin. Many of these solvents are also flammable. Various gasses are used in lasers such as the common inert gasses (helium, neon, argon, krypton, xenon, radon), in addition to much more dangerous gasses. This is especially true for excimer lasers. These lasers use combinations of halogen and rare gases to achieve lasing output, with gas mixtures that can include carbon dioxide, fluorine and hydrogen chloride. Various hazards are commonly encountered when working with compressed gases and gas cylinders. They include injuries caused by disruption and fragmentation of the gas cylinder or gas pressure regulator and associated equipment, gas escaping from cylinders, hoses, equipment, etc., with the possibility of fire, explosion and/or asphyxiation. It should be noted that compressed gases greatly increase in volume at atmospheric pressure so that for all types of gases (toxic or not) a small leak could rapidly fill a confined space and create an atmosphere that is oxygen rich, oxygen deficient, toxic and/or flammable. 5

7 Potentially hazardous airborne contaminants can be released into the atmosphere during laser operation for material processing. These can be produced by the vaporization/ablation of the target material when irradiated by a very high energy laser (generally Class 4). In addition, ultraviolet laser light can split oxygen molecules in the ambient air, which can form ozone (O 3 ), a gas that can rupture biological cell walls. Inhalation can cause a dryness of the mouth, coughing, and it irritates the nose, throat, and chest, causing difficulty in breathing, headaches and fatigue. The characteristic sharp, irritating odor is readily detectable at low concentrations (0.01 to 0.05 ppm). MISCELLANEOUS HARZARDS Hazards such as fire, noise, cryogenic and x-rays are present for some lasers. Some Class 4 lasers have sufficient power to create a fire hazard (e.g. CO 2 lasers). Liquid nitrogen and other cryogenic fluids are used in the cooling systems of certain lasers and detectors. Cryogenic fluids can cause sever burns and when evaporated they displace the oxygen required for breathing. 6

8 RESPONSIBILITIES This section outlines the responsibilities for 1) the Head of Department (HoD), 2) the Safety Officer (SO), 3) the Laser Safety Officer (LSO), 4) the deputy Laser Safety Officer (DLSO), 5) the Laboratory Managers (LMs) and 6) the Individual Laser Users (ILUs). The HEAD OF DEPARTMENT is responsible for: (a) appointing a Safety Officer (SO) (b) identifying all persons to whom the OFTC Laser Safety Program applies and ensuring that they clearly understand their duties and responsibilities; (c) ensuring that all components of the OFTC Laser Safety Program are implemented. The SAFETY OFFICER (SO) is responsible for: (a) appointing a Laser Safety Officer (LSO); (b) seeking advice from the LSO for all laser safety matters; (c) providing a copy of all ohsrm forms that identify laser hazards to the LSO; (d) reviewing and acting upon any recommendations by the LSO for the suspension, restriction, or termination of the operation of a laser or laser system which does not meet acceptable safety standards; (e) reporting annually to the HoD on the operation of the Laser Safety Program. The LASER SAFETY OFFICER (LSO) is responsible for: (a) establishing and maintaining the OFTC Laser Safety Program and the associated policies and procedures for the safe use of lasers within the OFTC; (b) reviewing and updating the laser safety program on a regular basis; 7

9 (c) appointing a deputy LSO (DLSO); (d) acting as the OFTC central contact for all laser safety issues and providing expert advice on laser safety hazards to all at the OFTC; (e) advising the lab managers of all required infrastructural laser safety requirements to properly locate any existing and/or newly purchased lasers or laser systems at the OFTC; (f) inspecting all new hazardous lasers and the associated safety requirements before operation; (g) classifying all "home-built" and modified lasers and laser systems; (h) acquiring and/or approving appropriate laser safety training program materials; (i) ensuring that all new personnel take a baseline eye exam (j) ensuring that all individual laser users have viewed the Laser Safety DVD; (k) providing or delegating personal laser safety training to the individual laser user as appropriate, but only after the previous two list items have been completed; (l) assessing, in the case of more experienced researchers, whether training received elsewhere is adequate and complies with the Australian/New Zealand Standards; (m) signing an authorised laser user form only after the previous four requirements have been completed to the LSO s satisfaction; (n) ensuring that personal protective equipment (eye wear, protective clothing) is suitable; (o) enforcing the safety standards defined in the Australian/New Zealand Standard Laser Safety policy (AS/NZS :2004); (p) reporting all incidents involving safety violations, accidents or injuries to the SO; (q) recommending the suspension, restriction, or termination of the operation of any laser or laser system which does not meet acceptable safety standards by documenting the technical reasons for the decision and reporting to the SO; (r) reporting annually to the SO on the operation of the Laser Safety Program. 8

10 The DEPUTY LASER SAFETY OFFICER (DLSO) is responsible for: (a) taking over the duties of the LSO in their absence for any urgent matters only and to the best of their abilities and (if possible) through seeking satisfactory advice from the SO and/or the LSO by phone or ; (b) Carrying out any duties that have been delegated to the DLSO, including performing the duties of the LSO where the LSO cannot access the specific lasers and/or laser labs, or when the deputy is more knowledgeable about the laser hazards in that specific laboratory. The LABORATORY MANAGERS (LMS) are responsible for: (a) ensuring all means are in place and operational to provide a safe environment for the day-to-day operation of the lasers by the authorized users in their laboratory; (b) seeking advice from the LSO on any laser safety concerns; (c) bringing any laser safety concerns to the attention of the LSO; (d) registering any potentially hazardous laser (Class 3R, Class 3B or Class 4 laser or laser system) by filling out the University of Sydney s Occupational Health and Safety Risk Management (ohsrm) form; (e) notifying the LSO before purchasing a potentially hazardous laser so that appropriate safety measures can be determined prior to first installation and operation; (f) seeking confirmation from the LSO that a laser is appropriately classified (note that the American Laser Safety Standards differ from Australian Standards, and there are indications that some lasers manufactured in Asia have been misclassified); (g) seeking approval from the LSO before any changes in operational status, such as location changes and/or modifications to any hazardous laser or laser equipment are made; (h) ensuring that Individual Laser Users (ILU) are referred to the LSO for registration so that Laser Safety training can be provided by the LSO or an authorized deputy determined by the LSO before operation of the hazardous laser; (i) providing written standard operating procedures (SOPs) for all hazardous lasers to authorized ILUs only and ensuring that each laser is used only under conditions and in locations which meet the requirements of the SOP; 9

11 (j) ensuring that personal protective equipment (eye wear, protective clothing) is suitable by seeking advice from the LSO; (k) providing and enforcing the use of personal protective equipment when required and ensuring that all administrative and engineering controls are followed; (l) ensuring that all lasers and laser systems are stored securely and safely when not in use so that they are not usable by unauthorized persons or under unauthorized conditions; (m) permitting only authorized ILUs to operate or work in proximity to hazardous lasers; (n) immediately acting on the identification of any unsafe conditions; (o) supervising all spectators, visitors and personnel when accessing the specific laboratory that is under the LM s control; (p) reporting to the LSO of any laser safety concerns, incidents, accidents or near accidents within 24hrs of the event. The INDIVIDUAL LASER USER (ILU) is responsible for: (a) notifying the relevant LM when they wish to operate a hazardous laser or wish to work in proximity of a hazardous laser; (b) reporting to the LM and LSO any medical conditions that could cause them to be at increased risk for chronic exposure, e.g. colour blindness, photosensitivity of the skin, use of photosensitizing medications and dermatological abnormalities of the skin; (c) participating in the University s medical base-line eye testing; (d) ensuring they are registered with the LSO as an authorised laser user prior to operating any hazardous laser; (e) being knowledgeable about the Standard Operational Procedures (SOPs) and all specific safety hazards of the hazardous laser they will operate; (f) operating the hazardous laser safely and in a manner consistent with general laser safety requirements and written SOPs; (g) operating hazardous lasers only under the conditions authorized by the LM; 10

12 (h) immediately reporting all unsafe conditions to the LM; (i) promptly reporting known, suspected or potential accidents and unsafe conditions to the LM; The Head of Department, the Safety Officer and the Laser Safety Officer have jurisdiction over all aspects of hazard prevention and control of laser radiation at the OFTC and have the authority to suspend any operation that constitutes a radiation health hazard to the equipment operators, University personnel, the general public or any other person. 11

13 PROCEDURES REGISTRATION There are two primary reasons for preparing and maintaining a record of all hazardous lasers (Class 3R, Class 3B and Class 4 lasers and laser systems). These are: (a) to identify areas where hazardous lasers are present so that appropriate administrative and engineering controls may be put in place; (b) to enable the lasers and laser systems to be inspected for compliance with the OFTC Laser Safety Program. All hazardous lasers must be registered by the LM on the University of Sydney ohsrm form for hazard identification and are to contain the following information: (a) type of laser (C02, Nd: YAG, He-Ne, etc). (b) production class (commercial, modified, "home-built") (c) manufacturers laser classification (Class 3B, Class 4 etc.) The LM is responsible for the registration of all hazardous lasers under their control and the de-registration of decommissioned lasers. All ILUs (including LMs who are ILUs) must be registered with the LSO prior to commencing working with hazardous lasers. TRAINING Each ILU must complete the "Laser Training Declaration Form with the LSO to be registered as an authorized user in the OFTC database after the ILU has been trained in and has knowledge of: (a) the University of Sydney Occupational Health and Safety guidelines at (b) the OFTC Laser Safety Program; (c) the laser hazards and ILU operator responsibilities outlined in this program; (d) the laser and general safety guidelines specific to the laboratory they will use; (e) the standard operating procedures and specific safety hazards of the lasers and laser systems that they will operate or oversee; (f) laser eye protection (goggles); (g) the procedures for filing (laser) accident reports. 12

14 INSPECTIONS (a) All newly registered hazardous lasers and their location must be inspected by the LSO prior to operation; (b) All LMs must allow inspections of lasers and laser locations upon request of the LSO; (c) All ILUs shall notify the LSO prior to any change in the laser or laser location or arrangement that may affects the safety of operators, personnel or property; (d) A laser inspection may be requested by any person in the OFTC who has concerns about the laser safety aspects of a particular laser or laser system. MEDICAL SURVEILLANCE All individuals intending to work with a Class 3B or Class 4 laser or laser system should have a baseline eye exam prior to the use or operation of such a laser. OFTC administration is to organise an appointment with the ophthalmologist to have this carried out and the costs are to be covered by the LM or the supervisor of the individual concerned. Note that these examinations have value for medical legal reasons and are not a necessary part of the safety program or provide any hazard protection as such. 13

15 CONTROL MEASURES Each laser and laser system must be designed to ensure that maximum protection is afforded to the operator. Only Class 1, 1M, 2 and 2M lasers may be used for demonstration purposes by authorised users. Class 1 lasers require no safety control measures Class 1M lasers are to be used without viewing aids Class 2 lasers require the following controls: (a) a protective housing; (b) a "Caution" logo must be attached to the laser and must read "Do not stare into the beam". Class 2M lasers require the same as Class 2 lasers with the addition that no viewing aids may be used. Class 3R lasers require the following controls in addition to the requirements needed for Class 2M lasers: (a) The laser area must be posted with the appropriate "Caution" sign; (b) Any protective housing must remain in place to prevent exposure to radiation from any source other than the defined aperture; (c) The protective housing must be interlocked to prevent exposure of personnel to unnecessary laser radiation when opened. The interlock must not be overridden during normal operation; (d) Beam stops for lasers must be permanently available, correctly positioned and be capable of preventing access to unnecessary laser radiation; (e) Each laser laboratory must keep written Standard Operating Procedures outlining safety, emergency, and where applicable, alignment procedures. Copies of these documents must be submitted to the LSO upon request. Any changes to any of these procedures must be forwarded to the LSO upon request. Class 3B and Class 4 lasers require the following controls in addition to requirements needed with Class 3R lasers: 14

16 (a) Class 3B and Class 4 lasers must only be operated in a suitable Controlled Laser Area (CLA), which must: a. have an assigned Lab Manager; b. be only accessible to authorized personnel and ILUs by selective distribution of the CLA lab key; c. not allow for any possibility of laser light to escape form the CLA, such as through windows or door panels; d. have an appropriate "Danger" label affixed at the entry point(s); e. have interlocks installed at the entry point(s) so that unannounced entry of any person results in an immediate removal of all hazardous laser light; f. have an intercom installed to allow communication between persons inside and outside the CLA without opening the door; g. have a flashing laser warning light located at the entry point(s) to indicate laser operation, activated with the interlock system prior to emission of the beam; h. have appropriate protective eye wear (goggles) available at the entry point(s) that are to be worn before opening the CLA door when the laser is in operation; i. have a clearly visible power cut off switch present; j. have no chairs present as this may bring eyes to the level of the laser beams; (b) When more than one Class 3B or Class 4 laser is present in a CLA, it must be indicated on the door which laser/lasers is/are in operation. Anyone entering the CLA should confirm this by intercom. This ensures that the correct goggles can be worn before entering; (c) The appropriate "Danger" label must also be affixed to the protective housing of the laser itself; (d) A master switch (either a key or coded access) must be present, which, when removed, must make the laser inoperable. (e) The laser beam path must be configured such that the beam is always well below eye level of a person in standing position. (f) Protective clothing must be provided as required. (g) Backstops must be constructed of diffusely reflecting material and, when practical, fire resistant material. (h) Hazardous beams must be enclosed as much as possible and terminated in an appropriate beam stop; 15

17 (i) All Materials capable of specular reflections should be avoided as much as possible and preferably should be entirely removed from the CLA; only diffusely reflecting materials may be near the beam path; (j) Jewelry or watches must not be worn as they can lead to specular reflections. Failing to remove jewelry and watches forms one of the most common causes of laser eye injuries! (k) Appropriate Fire extinguishers should be located in the vicinity of the CLA when the laser is deemed a fire hazard (Class 4) and flammable materials should be kept well clear of the beam path and preferably should be removed. (l) When no goggles are available at the entry point of a CLA, entry is not permitted. GENERAL REQUIREMENTS (a) It is recommended to operate lasers in well lighted areas whenever possible to reduce pupil size which minimizes possible eye damage. (b) It is advised to always use the lowest possible beam power for any procedure. (c) Set up the optical components necessary for the experiment as much as possible before operating the laser. (d) Check that all beam stops are in place and that there are no unnecessary reflective surfaces in the optical path. (e) See that all unauthorized people leave the room before operating a laser. (f) Cryogenic fluids required for some lasers and detectors should only be used with appropriate skin protection and in well-ventilated areas. (g) A laser beam must never be intentionally stared into or directed towards a person or towards a laboratory entry point. (h) If a laser operator suspects that a safety hazard may exist, the operator should request the LSO to conduct a laser safety inspection. (i) Have emergency telephone numbers readily available and be familiar with the other OFTC Safety guidelines and procedures (e.g. building evacuation). (j) The LSO may apply additional safety requirements as deemed necessary to protect the health of the operators, University personnel, the general public or any other persons. 16

18 RECOMMENDED WORKING PRACTICES FOR LASER LIGHT IN OPTICAL FIBRES When laser light is confined inside an optical fibre the potential hazards are much reduced as compared to laser beams in free space. There are, however, so-called accessible locations where the laser light becomes accessible to the user and consequently becomes hazardous. Such accessible locations can be intentional (e.g. a fibre connector) or unintentional (e.g. at a fibre breakage point). At the OFTC, all of the above laser safety procedures and control measures still apply to laser light that is transmitted in optical fibres ( live optical fibre). The following are examples of good working practices with optical fibres and are recommended when working with any optical fibre system. Please note that due to the diversity of optical fibre systems at the OFTC, different working practices may apply in different circumstances. (a) Do not point live fibre ends or connector faces at yourself or other people. Do not look at live fibre ends or connector faces with the unprotected eye. (b) Use indirect viewing aids were possible (e.g. by camera or shadow-imaging splicing machines). Use only filtering or attenuating viewing aids approved by the LSO. (c) Only use a microscope to view live fibre output/transmission when the light source used is a Class 1 source. Do not use a microscope to view live fibre output when any other source is used. (d) Any unterminated single or multiple fibre ends should be individually or collectively covered when not being worked on. They should not be visible and sharp ends should not be exposed. Suitable covering methods include the use of a splice protector or tape. End caps should always be attached to unmated connectors. (e) When using optical test cords or a connected optical fibre system, the fibre of the optical power source should be the last to be connected (before turning the source on), and the first to be disconnected (after turning the source off). (f) All (non-plastic) fibre off-cuts should be collected and disposed of in an approved sharps bin. (g) Live working on fibres transmitting laser light of Class 3B or Class 4 is not recommended. (h) When live working on fibres transmitting laser light of Class 3B or Class 4 is necessary, however, it should be limited as much as possible, and performed only by appropriately highly-trained personnel whilst closely following all of the above recommendations. 17

19 REFERENCES (available from the Laser Safety Officer on request) (a) Australian/New Zealand Standard Safety of laser products Part 1: Equipment classification, requirements and user s guide (IEC :2001, MOD) AS/NZS :2004 (b) Australian/New Zealand Standard Safety of laser products Part 10: Application guidelines and explanatory notes (IEC TR :2002, MOD) AS/NZS :2004 (c) Australian/New Zealand Standard Laser Safety Part 2: Safety of Optical fibre communication systems AS/NZS :2004 (d) University College, UNSW, Australian Defence Force Academy Continuing Education Programme Introductory Laser Safety Course 6 Dec 2005 Presented by the School of information technology & Electrical Engineering, course lecturer Geoff Cochrane. FORMS (a) The ohsrm forms are available from the OFTC intranet (b) Examples of Laser Standard Operating Procedures are available from the Laser Safety Officer 18