Laser Safety Retraining for users of Class 3B and Class 4 lasers Revision: Summer 2008

 Class 1: exempt from control measures or other surveillance, considered incapable of producing damaging radiation levels during operation. Former Class IIa lasers are considered to be in this category.  Class 1M: exempt from any control measures other than to prevent potentially hazardous optically aided viewing, considered incapable of producing hazardous exposure conditions during normal operation unless the beam is viewed with an optical instrument.

Both Class 2 and Class 2M laser emit only in the visible spectrum (400 – 700 nm wavelengths). In the visible spectrum, the human aversion response (a reflex action of blinking and looking away from a strong optical stimulus) occurs when the eye becomes exposed; the response time occurs within 0.25 seconds.  Class 2 lasers are considered harmless for accidental viewing based on the power level and protection of the human aversion response.  Class 2M lasers are considered potentially hazardous if viewed with certain optical aids. For instance, a focusing lens may produce a magnified intensity to which the eye could be exposed. The Laser Safety Officer should evaluate a Class 2M laser or laser system to determine what hazard controls may be necessary for the safe use of the laser.

 Class 3 (medium power): may be hazardous for direct or specular reflections (normally not a diffuse reflection or fire hazard). 2 subclasses.  Class 3R: potentially hazardous under some direct and specular reflection viewing conditions (if eye is focused and stable, highly improbable). Not a fire or diffuse reflection hazard.  Class 3B: viewing hazard under direct or specular reflection conditions, normally not a diffuse reflection or fire hazard

 Class 4 (high power):  Hazard to eye or skin from the direct beam, and  May be a diffuse reflection or fire hazard  May also be a source of laser generated air contaminants (LGACs) and hazardous plasma radiation.  For lasers not classified by manufacturer, or where class level may change because of alteration of engineering control measures, the Laser Safety Officer (LSO) may classify  Laser classifications are in Arabic Numerals; Roman Numerals are no longer accepted.

 Only exist when laser is in operation  Target Organs:  Eye  Skin  Maximum Permissible Exposure (MPE) limits are set below known hazardous levels.  Exposures at the MPE limit may be uncomfortable.

 Thermal  Potential effects: charring, edema, hemorrhage  Photochemical (blue light and UV)  Potential effects: production of toxins and biochemical changes which may cause inflammation, lesions and lens opacities  Photoacoustic (short intense pulses)  Potential effects: explosive forces due to expanding gases

TARGET: Cornea Far IR (IRC): 3000 nm – 1 mm Mid IR (IRB): 1400 nm – 3000 nm Mid UV (UVB): 280 nm – 315 nm Far UV (UVC): 100 nm – 280 nm EFFECT: Mid IR and Far IR: Thermal Mid UV and Far UV: Acute inflammation and conjunctivitis, fluorescence of lens, corneal and lenticular opacities (“clouding”) cataractogenesis (peaks at 300 nm)

TARGET: Retina Near IR (IRA) : 700 nm – 1400 nm Visible Light: 400 nm – 700 nm EFFECT: Thermal burns, hemorrhage, scotoma (“blind spot”), photoretinitis (“blue light damage”)

TARGET: Lens Near UV (UVA): 315 nm – 400 nm EFFECT: Development of cataracts

 Lower MPE limits may be required when normal protective mechanisms such as eye movement and pupil constriction are hindered. Inform your LPI if you think that you have a condition that may impact your susceptibility to the laser beam.  For example, individuals who have had pupil dilation performed will not have the natural defenses of the constricting iris which could limit that amount of radiation entering their eye.  Also, advanced age of an individual may reduce the ability of the iris to contract.

 Thermal (from direct beam or specular reflection) for Near UV, Visible, and IR wavelengths  Potential effects: mild reddening (erythema) to blistering  Severity is dependent upon exposure dose rate, exposure dose, and conduction of heat away from the site of absorption

 Photochemical (from scatter of beam, specular or diffuse reflection) for Mid UV and Far UV wavelengths  Potential effects: erythema to blistering, possibly carcinogenic  Effects are dependent upon wavelength and exposure dose

 Specular (Mirror-Like)  Diffuse (Blurred) “Smooth” surface – wavelengths reflect uniformly at same angle “Rough” surface – wavelengths are absorbed or reflected at various angles

 Avoid having objects that may produce a specular reflection in or near laser beam (e.g. jewelry, tools, etc.), unless deliberately used as part of laser system (e.g. mirrors)  Reflection type is wavelength dependent; surfaces that appear dull and pitted to our eyes may be a specular surface to beams of larger wavelengths

 Include physical, chemical, and biological agents, as well as human use issues.  May occur:  When material is exposed to a laser beam.  When laser-related materials are released into the atmosphere.  When individuals contact system components.  Regardless of whether the laser unit is in operation or not.  Written SOPs shall address non-beam hazards, as well as beam hazards. Written SOPs

 Electrical Hazards  Potential Hazards: shock, resistive heating, electric spark ignition of flammable  Potential effects: “tingle”, startle, serious injury, death.  Collateral and Plasma Radiation  Ionizing Radiation: x-rays from electronic components of laser system (e.g. voltages exceeding 15 kV) and laser- metal induced plasmas.  Non-Ionizing Radiation: UV and Visible, Electromagnetic Fields (EMF), Plasma

 Fire Hazards: possible affected material include beam enclosures, barriers, unprotected wire insulation, and plastic tubing.  Explosion Hazards: component (high-pressure arc lamps, filament lamps, and capacitor banks) disintegration, laser target and elements of the optical train may shatter, chemical laser reactants or other laser gases, ignition of dust collected in ventilation systems serving laser processes.  Mechanical Hazards Associated with Robotics: damage to protective housing and beam delivery system, misalignment of beam, pinning/pinching of personnel.  Noise: certain lasers (e.g. pulsed excimers), and/or work environment may require noise control.

 Laser Generated Air Contaminants (LGACs)  Primary Factors: target material, cover gas, and the beam irradiance (lower threshold limit of approximately 10 7 W/cm 2 ).  Compressed Gases: e.g.: chlorine, fluorine, hydrogen chloride, hydrogen fluoride.  Laser Dyes and Solvents: fluorescent compounds which, when in solution with certain solvents, form a lasing medium for dye lasers.  Assist Gases

 Control Measures: Engineering controls preferred  Exhaust Ventilation  Respiratory Protection  Process Isolation  Sensors and Alarms  Shall be installed in hazardous gas cabinets and other locations as appropriate (including exhaust ventilation ducts).  Should be used for toxic and corrosive chemical agents (e.g. halogens), and be able to detect the hazardous gas in a mixture of emitted gases.  Must be properly shielded to minimize susceptibility to electromagnetic interference (EMI).

 LGACs: may be generated when a high power laser interacts with biological tissue.  Infectious Materials: may survive beam irradiation and become airborne.  Must have approval of Biological Safety Officer to conduct work with biohazardous material.Biological Safety Officer

 Ergonomics  E.g.: workstation layout, worker-machine interface, handling techniques, area illumination, visual distractions.  Limited Work Space  There must be sufficient room for personnel to turn around an maneuver freely, without trip/fall hazards (e.g. wires or cables on floor).  Work Patterns  Unusual or long hours may affect worker alertness.

 Disposal  Laser Disposal: remove all means of activation and dispose (i.e. render inoperable) and inform LSO of disposal  Laser Waste Disposal: waste disposal shall conform with Purdue University disposal requirements (see REM’s Hazardous Material Management webpage) REM’s Hazardous Material Management webpage  Chillers  May be employed to reduce heat load produced by lasers.  If using chilled water, filter the incoming water to ensure that minerals and particulate matter are removed to minimize damage to equipment.

 Use minimum laser radiation required for the application.  Maintain beam height at a level other that the position of the user’s eye standing or sitting.  Prefer engineering controls, however must have administrative and procedural controls.

 Reported incidents related to lasers are most often associated with:  Unanticipated eye exposure during alignment  Misaligned optics and upwardly directed beams  Available eye protection not used  Equipment malfunction  Improper methods of handling high voltage  Intentional exposure of unprotected personnel  Operators unfamiliar with laser equipment  Lack of protection for non-beam hazards

 Reported incidents related to lasers are most often associated with (cont’d):  Improper restoration of equipment following service  Eyewear worn not appropriate for laser in use  Unanticipated eye/skin exposure during laser usage  Inhalation of laser generated air contaminants and/or viewing laser generated plasmas  Fires resulting from the ignition of materials  Eye or skin injury of photochemical origin  Failure to follow SOPs

 Lasers are classified under conditions of intended use.  Maintenance and Service functions should be delineated in the service manuals of the laser.  Consult with manufacturer for special use conditions/service of laser.  Consult REM laser section for guidance on service procedures at m m

 Operate lasers under direct supervision or control of an authorized unrestricted user or LPI – operator shall maintain visual surveillance of conditions for safe use and terminate laser operation in the event of malfunction or other unsafe condition.  Unattended operation may ONLY be allowed under LSO-approved control measures are in place; control measures MUST provide adequate protection so that unprotected spectators shall not receive eye or skin exposures that exceed the MPE limits.  Service Personnel  Emergency Personnel  Administrative/Other Personnel  Students/General Public

 General – enclosure of beam is the preferred method of control.  Eyewear – required within Nominal Hazard Zone (NHZ) for Class 3B and 4 lasers  Windows within NHZ shall be provided with an appropriate filter, barrier, or screen which reduces laser radiation to below applicable Maximum Permissible Exposure (MPE).  Barriers and Curtains – material used shall be rated to withstand accidental direct and diffuse reflection of beam without combustion or release toxic fumes.  Skin Protection - mostly applicable to Class 4 UV lasers  Other Protective Equipment – respirators, local exhaust ventilation, fire extinguishers, hearing protection, or additional controls may be required.

 Area warning signs for Class 3B and Class 4 lasers must be posted at the NHZ  For Service of laser, special postings must be placed at NHZ  Laser labels may be placed on laser and (if applicable) control console  Non-use tags: attached to laser – may only be removed by the LSO.

 Laser Classification Label: placed anywhere on laser; states laser’s classification (and often wavelength, power, etc.)  Laser Aperture Label: shall be placed where laser will become an exposed beam

 LSO has authority and responsibility to evaluate laser hazards, monitor and enforce compliance with required standards and regulations, and perform other specific duties and responsibilities.  Laser Safety Committee provides oversight of the laser safety program and has the power to create policy.

 Establish the safe use of the laser or laser system that is used.  Inform LSO of any fabrication, altering, or installation of a Class 3B or Class 4 laser or laser system.  Comply with the requirements as set forth by the ANSI Standard Z136.1 (2007) and Purdue University Laser Safety Guidelines, found at: e.pdf e.pdf  Different expectations for different personnel types  Laser Principal Investigator (LPI)  Restricted and Unrestricted Users

 Issue appropriate instruction and training materials on laser hazards and their control to all personnel who may work with lasers that are operated within LPI’s jurisdiction.  Not permit the operation of a laser unless there is adequate control of laser hazards to employees, visitors, and the general public.  Ensure all individuals working have submitted a completed LU-2 form, including LPI  Ensure LU-1 (that must be submitted to LSO) has all authorized individuals listed. Subsequent users may be listed with all required information either as an LU-1 addendum, or by written documentation to LSO.  Ensure an LS-1 form (that must be submitted to LSO) is completed for all Class 3B and Class 4 lasers under LPI’s jurisdiction. This does NOT NECESSARILY pertain to ownership – lasers that are borrowed, leased, etc. also fall under this scope.

 For any known or suspected accident relating to a laser under his/her authority, enact appropriate response plan, which includes notification of the LSO.  If necessary, assist in obtaining appropriate medical attention for any employee involved in a laser accident.  Not permit operation of a new or modified Class 3B or Class 4 laser under his/her authority without LSO approval.  Shall submit plans for Class 3B and Class 4 laser installations/modifications of installations to the LSO for review.  Shall be familiar with the Standard Operating Procedures (SOPs) for each Class 3B and Class 4 laser under his/her authority, and ensure that that they are provided to all users of such lasers.

 Not energize or work with or near a laser unless authorized to do so by the LPI.  Comply with Purdue University Laser Safety Guidelines, LSO and LPI safety rules and procedures.  Inform his/her LPI of any known or suspected accident involving a laser under their LPI’s jurisdiction. If the LPI is not available, notify the LSO.

 PERSONNEL INJURY  Turn off the laser system with the “Emergency Button” or power switch.  If injured personnel require medical assistance, don appropriate Personal Protective Equipment (PPE, i.e. gloves), and provide minimum assistance, as needed. Ensure someone remains with the victim until medical personnel arrive.  Contact medical personnel (call 911). Inform them of the accident and that lasers are involved.  Contact REM ( ).  Complete incident report.  Medical surveillance must be performed as soon as possible, but no later than 48 hours of a suspected or actual laser-induced injury.

 FIRE  Sound fire alarm.  Contact fire department (call 911). Inform them of the incident.  If fire has gone out, call the Purdue University Fire Department (PUFD) at the non-emergency number ( )  Turn off the laser system with the “Emergency Button” or power switch.  Evacuate area.  Contact REM ( ).  Complete incident report.

 Mary J. Handy, Laser Safety Officer    James F. Schweitzer, Director, Radiological and Environmental Management    Other Radiation Safety Staff:

You must have 70% of correct answers to pass the retraining - you will receive pass/fail notification to the address you submit on the online form. Click the following link when you are ready to take the test: Laser Safety Retraining 2008 Quiz