Laser Safety Training Environmental Health and Life Safety (EHLS) 713-743-5858 http://www.uh.edu/ehls This course provides Course Basic understanding of lasers and how they function General understanding of Laser hazards General instructions on how to work safely with lasers, and how to be protected from potentially harmful radiation An overall safety awareness in laser use labs. Based on the Texas Regulations for the Control of Radiation This course covers basic laser radiation safety, physics, and biology and is not intended to be exhaustive on these subjects. LASER LIGHT PROPERTIES 1
Laser Light Properties The light output of a laser differs from the output of ordinary light sources. Four properties characterize the laser s output: Small Divergence Monochromatic Coherence High Intensity Laser Light Properties Divergence When light emerges from the laser, it does not diverge (spread) very much at all. Thus the energy is not greatly dissipated as the beam travels. Monochromatic Laser Light is very close to being monochromatic. The term monochromatic means one color, or one wavelength, of light. Actually, very few lasers produce only one wavelength of light. Laser Light Properties Coherence Coherence is a term used to describe particular relationships between two wave forms. Two waves with the same frequency, phase, amplitude, and direction are termed spatially coherent. High Intensity Laser light can be very intense. Energy is a measure of capacity for doing work and is measured in joules (J) in the metric system. Power is the rate at which work is being done and is measured in watts (W). 1 joule = 1 watt second 1 watt = 1 joule/second A laser capable of emitting 10 joules per second can be termed a 10 watt laser. If the same 10 joules are emitted as a single pulse of 1/100 th second duration, then the laser can be termed a 1,000 watt laser. Irradiance = W/cm 2 Radiant Exposure = J/cm 2 2
FUNDAMENTAL DEFINITIONS Definitions Maximum Permissible Exposure Limit (MPE) the level of laser radiation to which an unprotected person may be exposed without adverse biological changes in the eye or skin Nominal Hazard Zone (NHZ) the space within which the level of the direct, reflected, or scattered radiation may exceed the applicable MPE. Exposure levels beyond the boundary of the NHZ are below the appropriate MPE. Definitions CW Laser a continuous wave laser whose output persists for a relatively long interrupted time interval, while the laser is turned on. Pulsed Laser a pulsed laser whose output occurs in short, interrupted time intervals, in contrast to a CW laser. 3
Definitions Beam Divergence the increase in beam diameter with distance measured from the aperture of the laser. Power Density A term used to denote the power emitted per unit area per solid angle (watts per square centimeter per steradian). It is equivalent to the radiometric term irradiance. BASICS OF LASERS AND LASER LIGHT L ight A mplification by S timulated E mission of R adiation Thus the laser is a device which produces and amplifies light Laser-Professionals.com Laser Components Three components are necessary for laser construction and operation An active lasing medium An input energy source (Called a Pump ) An optical Resonator 4
LASER COMPONENTS-Summary Optical Resonator Active Medium Output Beam High Reflectance Mirror (HR) Excitation Mechanism Output Coupler Mirror (OC) All lasers have the same basic design. Lasing Medium Lasers can be classified according to the state of the lasing media Solid state lasers employ a lasing material distributed in a solid matrix Ex. Ruby laser Gas lasers use a gas or mixture of gases within a glass tube Ex. HeNe, CO 2, Argon, and Krypton Change energy levels Lasing Medium Liquid lasers are usually a complex organic dye with the most versatile feature of tunability ; and proper choice of the dye and its concentration allows light production at almost any wavelength in or near the visible spectrum Ex. Dye laser 5
Energy input source-pumps Laser action can occur only when a population inversion has been established in the lasing medium. Several methods of pumping are commonly used. Optical pumping is employed in solid state and liquid lasers. Xenon flashtubes are commonly used for solid state lasers and liquid lasers usually are pumped by a beam from another solid state laser. Electron collision pumping is utilized in gas lasers. An electrical discharge is sent through the gas-filled tube. Optical Cavity Once the lasing medium has been pumped and a population inversion obtained, lasing action may begin. Without an optical cavity the direction of beam propagation would be produced in all directions leading to super-radiant lasing. The beam of propagation can be controlled by placing the lasing medium in an optical cavity formed by two reflectors facing each other along a central axis. Photon beams which are produced along that cavity are reflected 180 0 at each reflection and travel once more through the lasing medium causing more stimulated emission. Thus the beam grows in magnitude with each traverse of the lasing medium. Optical Cavity Reflectors may consist of plane mirrors, curved mirrors, or prisms. Reflectors are not 100% reflective, Some photons may be lost by transmission through the mirrors with each passage. With continuous pumping, a state of equilibrium will soon be reached between the number of photons produced by atoms raised to the excited state and the number of photons emitted and lost. Result: a continuous laser output, usually used only with low power input levels. 6
Higher power inputs usually are achieved in the form of a pulse form. One of the mirrors in the system is usually made more transparent than the other and the output, pulsed or continuous, is obtained through the reflector. A Q-switch is a device which interrupts the optical cavity for a short period of time during pumping. Q-switching is used to produce an exceptionally high-power output pulse. All lasers have the same basic design. The active medium contains the atoms that produce laser light by stimulated emission - This can be a solid crystal, a gas, a semiconductor junction, or a liquid. The excitation mechanism is the source of energy that excites the atoms to the proper energy level for stimulated emission to occur. Solid state lasers use optical sources for excitation; gas lasers use electrical excitation. The active medium and excitation mechanism together form an optical amplifier. Laser light entering one end of the amplifier will be amplified by stimulated emission as it travels through the active medium. The optical resonator is a pair of mirrors at the ends of the active medium. These mirrors are aligned to reflect the laser light back and forth through the active medium. The output coupler has a lower reflectance and allows some of the laser light to pass through to form the output beam. The fraction of the light that is allowed to pass through the output coupler depends on the type of laser. 7
VIDEO Slides Covered or Supplemental to Video Laser Spectrum Lasers operate in the ultraviolet, visible, near infrared, and far infrared regions of the spectrum. Visible light has a wavelength range of 400 700 nm It and can be seen by the eye. The fact that you can see this light helps you avoid hazardous exposures. The near infrared has a range of 700 1400 nm. It cannot be seen because the retinal receptors do not work at these wavelengths. However, the optical elements of the eye transmit the NIR and focus these wavelengths on the retina. This produces an invisible retinal hazard and the potential for serious eye injury in the near IR. The most stringent laser safety precautions are required in this wavelength range. It also contains several of the most useful lasers. 8
Ultraviolet below 400 nm Ocular Focus 400 to 1400 nm retinal hazards which contain two distinct subranges 400 to 700 nm visible portion of spectrum and provides the light the eye uses to see with Colors - Blue 450 nm Green 500 nm Yellow 550 nm Orange 600 nm Red 700 nm 700 to 1400 nm also permitted by ocular components except that the retina, which also absorbs this range of wavelengths does not see them (invisible) Infrared above 1400 mm UV and IR wavelengths are not transmitted through the cornea and other exterior parts of the eye. Not focused on the retina and therefore magnification of laser light energy is not possible LASER SPECTRUM Gamma Rays X-Rays Ultra- Visible Infrared Micro- Radar TV Radio violet waves waves waves waves 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1 10 102 Wavelength (m) LASERS Retinal Hazard Region Ultraviolet Visible Near Infrared Far Infrared 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 10600 ArF XeCl 193 308 KrF Ar 248 488/515 HeNe Ruby 633 694 2 Alexandrite GaAs Nd:YAG 755 905 532 Nd:YAG 1064 Wavelength (nm) Communication Diode 1550 CO 2 10600 Laser-Professionals.com Laser Classification ANSI Z136.1 emphasizes that It must be recognized that this classification scheme relates specifically to the laser device and its potential hazard, based on operating characteristics. However, the conditions under which the laser is used, the level of safety training of persons using the laser, and other environmental and personnel factors are important considerations in determining the full extent of safety control measures. Beam Reflections laser beams are reflected to some extent from any surface contacted. Essentially all reflections of laser beams result in spreading the beam or beam divergence Specular If reflecting surface is shiny like a mirror Diffuse If reflecting surface is not shiny 9
Laser Classes; ANSI Z136.1 (2007) Class 1 (I) Class I M Class 2 (II) Class 2 M Class 3 R (Class 3a) Class 3B Class 4 Class 1 Class 1 - Exempt Lasers Produce levels of radiation that have not been found to cause biological damage This group is normally limited to gallium-arsenide lasers or certain enclosed lasers Incorporated into consumer or office machine equipment Safety Precautions No laser specific rules, however general lab safety rules still apply Class 2 Class 2 - Low power and low risk Produce radiation that could cause eye damage after direct, long term exposure Hazardous only if viewer overcomes natural aversion response to bright light and continuously stares into source. Like blinding oneself by forcing oneself to stare at the sun for more than 10 to 20 seconds. Example lasers: grocery laser scanners Safety Precautions Never permit a person to stare into the laser source Never point the laser at an individuals eye 10
Class 3 (A and R) Class 3 - Moderate Risk or Medium Power Produce radiation powerful enough to injure human tissue with 1 short exposure to the direct beam or its direct reflections off a shiny surface. However, not capable of causing serious skin injury or hazardous diffuse reflections under normal use. Class 3B Safety Precautions for Class 3B Do not aim the laser at an individuals eye Permit only experienced personnel to operate the laser Enclose the beam path as much as possible. Even a transparent enclosure will prevent individuals from placing their head or reflecting objects within the beam path Termination should be used at the end of the useful paths of the direct and any secondary beams Operate the laser only in a restricted area Class 3B Continued Place the laser beam path well above or well below the eye level of any sitting or standing observers whenever possible The laser should be mounted firmly to assure that the beam travels only along its intended path Always use proper laser eye protection for the direct beam or a specular reflection Key switch to prevent tampering by unauthorized individuals Remove all unnecessary mirror-like surfaces from within the vicinity of the laser beam path 11
Class 4 Class 4 - High Power, High risk of injury and can cause combustion of flammable materials. May also cause diffuse reflections that are eye hazards and may also cause serious skin injury from direct exposure Safety Precautions Class 3B safety precautions and; Should only be operated within a localized enclosure or in a controlled workplace If complete local enclosure is not possible, Interlocking of room Eye wear is needed for all individuals working within the controlled area Backstops should be diffusely reflecting - fire resistant target materials Laser Radiation Hazards LASER BEAM INJURIES High power lasers can cause skin burns. E.g. CO 2 Laser used for medical applications Lasers can cause severe eye injuries resulting in permanent vision loss. 12
CAUSES OF LASER ACCIDENTS Studies of laser accidents have shown that there are usually several contributing factors. The following are common causes of laser injuries: Inadequate training of laser personnel Alignment performed without adequate procedures Failure to block beams or stray reflections Failure to wear eye protection in hazardous situations Failure to follow approved standard operating procedures or safe work practices TYPES OF LASER EYE EXPOSURE LASER INTRABEAM VIEWING EYE SPECULAR REFLECTION REFLECTED BEAM LASER MIRROR DIFFUSE REFLECTION LASER SCATTERED LIGHT ROUGH SURFACE Biological Effects Laser light can cause damage to living tissue. The extent of damage to living tissue caused by laser light depends primarily upon: Frequency of the light Power density of the beam Exposure time Type of tissue struck by the beam 13
Biological Effects Damage can occur through 2 mechanisms of interactions: Thermal Effect Absorbed energy produces heat The rapid rise in temperature can denature the protein materials of tissue, much as an egg white is coagulated when cooked Light absorption in tissue is not homogeneous and the thermal stress is greatest around those portions of tissue that are the most efficient absorbers Elastic or Acoustic Transient or Pressure Wave Mechanical compression wave, can rip and tear tissue Biological Effects Hazards Laser light is usually only a hazard to those tissues through which the light beam can penetrate and which will absorb the wavelength involved We are concerned primarily with two organs, the eyes and the skin Of the two, the eye is often far more vulnerable to injury than the skin from visible and near-infrared laser radiation, thus it is considered the organ most important to protect from all wavelengths of laser radiation Skin Anatomy Biological Effects The other area of concern is the skin. It is not as sensitive as the eye, and if damaged, most injuries are more easily repaired. However it too is subject to great damage from laser impact when energy densities approach several J/cm 2. The skin is not a homogeneous mixture. It is a specialized, layered structure with numerous odd inclusions, such as blood vessels and hair follicles. The skin is relatively transparent to laser light and absorption in the skin occurs, for the most part, in the pigment granules and the blood vessels. 14
Thermal & Photochemical Thermal-injuries are caused by heating of the tissue as a result of the absorption of laser energy Micro-cavitation-a type of thermal effect that occurs when a short laser pulse is focused onto the retina (can ruptures blood vessels in the retina) Photochemical- injuries occur because high energy photons break molecular bonds inside living cells SKIN BURN FROM CO 2 LASER EXPOSURE Accidental exposure to partial reflection of 2000 W CO 2 laser beam from metal surface during cutting Other Photochemical effects Other UV photochemical effects include welder s flash (Phtokeratitis), cataracts, and skin cancer from long term low level exposures. 15
Biological Effects Eye Damage The portion of the eye affected by the laser is dependent upon the wavelength of the light. Injury to the anterior portion of the eye Cornea is sensitive to very short wavelengths UV and long wavelengths in the IR range such as the 10,600 nm output of carbon dioxide lasers Other anterior structures such as the iris and lens are sensitive to wavelengths between 315 and 400 nm. Important note to remember is that exposures to the lens one day may cause effects which will not become evident for many years Biological Effects Biological Effects Injury to posterior portion of eye The retina can be damaged by lasers that operate in the visible and invisible range such as: Ruby 694.3 nm HeNe 632.8 nm Kr 488-650 nm Ar 455-529 nm Nd:YAG 1064 nm, 532 nm Ti:Sapphire 650-1100 nm He:Ne 543-1152 nm 16
25 THERMAL BURNS ON PRIMATE RETINA Laser-Professionals.com Photo courtesy of U S Air Force EYE INJURY BY Q-SWITCHED LASER Retinal Injury produced by four pulses from a Nd:YAG laser range finder. Photo courtesy of U S Army Center for Health Promotion and Preventive Medicine MULTIPLE PULSE RETINAL INJURY 17
Eye Protection Protective eyewear shall be worn by all individuals with access to Class 3b and/or Class 4 levels of laser radiation. Protective eyewear devices shall provide a comfortable and appropriate fit all around the area of the eye; be in proper condition to ensure the optical filter(s) and holder provide the required optical density or greater at the desired wavelengths and retain all protective properties during its use; be suitable for the specific wavelength of the laser and be of optical density adequate for the energy involved; have the optical density or densities and associated wavelengths(s) permanently labeled on the filters or eyewear; and examined, at intervals not to exceed 12 months, to ensure the reliability of the protective filters and integrity of the protective filter frames. Unreliable eyewear shall be discarded. Laser Eyewear Laser Eyewear Laser eyewear is not for direct viewing. >10 W power, eyewear will protect for about 3 seconds. >100 W power will burn the eyewear almost instantly. EXTREME EYE SAFETY HAZARD, uncoated polycarbonate transmits 10,600 nm CO2 laser light (ABSOLUTELY will NOT protect the eyes): Acrylic (most versions) stops 10,600 nm wavelength. 18
Skin Protection When there is a possibility of exposure to laser radiation that exceeds the MPE limits for the skin, the registrant shall require the appropriate use of protective gloves, clothing, or shields. Non Beam Laser Radiation Hazards Non Beam Hazards Chemical Hazards Physical Hazards Biological Hazards Human Factors 19
Non-Beam Hazards Mostly from High powered Lasers Applications like material processing, medical procedures, etc give rise to respiratory hazards Laser welding, cutting and drilling procedures generate potentially hazardous fumes and vapors Plume from laser tissue interactions- hazard during laser surgery Non-Beam Hazards Continued Electrical shock/electrocution Use proper controls when working with dangerous high voltage Noise hazards up to 140 db Cryogenic coolants e.g. nitrogen Non-Beam Hazards Continued LGAC (Laser generated airborne contaminants) Benzene, Toluene, HCl, Naphthalene, carbon monoxide, Fluorine, etc. Aerosols Metal Oxides, Organic, Biologicals Dust, mist, fume, fog, smoke, smog, Laser Dyes and Solvents Dyes some are toxic, mutagenic Solvents irritation, anesthetics, maybe flammable Potential for contaminated parts 20
Non-Beam Hazards Continued Collateral and Plazma Radiation X-ray may require shieling if above 15kV: Thyratron switched in pulse lasers and free electron lasers UV Plasma radiation, from material processing on metals: Nd:YAG and CO 2 Visible brightness, blue light hazards(possible damage to retina): Nd:YAG and CO 2 Infrared Interact with stainless steel and generate bright blue wavelength (plasma) Non-Beam Hazards Continued Radio Frequency Pulsed Nd:YAG and CO 2 Extremely Low Frequency Pulsed Nd:YAG, class IIIR HeNe Fire Normally limited to combustion of flammable materials such as paper by CW lasers operating with an output greater than 0.5 W, class 4 Class IIIB laser will ignite dust in dusty environment Depends on enclosure materials, construction materials, target materials, laser gases, vapors, LGAC Non-Beam Hazards Continued Explosion May exist due to high pressure arc lamps, filament lamps, target, dust collection explosion, etc. 21
Non-Beam Hazards Continued Compressed Gas Cylinders Do not drop cylinders or permit them to strike each other violently Where caps are provided for valve protection, keep such caps in place except when the cylinders are in use Do not force connections that do not fit Never lubricate, modify, force, or tamper with a cylinder valve Chain or strap cylinders securely in place so they will not fall over When cylinders are not in use, keep valves tightly closed Handle empty cylinders as though they were full; Keep them chained or strapped, and store them away from full cylinders Transport cylinders with cap in place and use a hand truck to which they can be strapped or chained Make sure cylinders are labeled to identify the contents Know the identity of the gas you are using, and be familiar with its properties Break 10 minutes 22
Laser Safety Standards and Regulations Regulatory Agencies/Standards Texas Department of State Health Services (DSHS) [Regulates university of Houston through a Certificate of Laser Registration] Food and Drug Administration (FDA) The American National Standard for Safe Use of Lasers (ANSI Z136.1) This is a VOLUNTARY Standard that applies to the use of lasers. It is recognized by : The Occupational Safety and Health Administration (OSHA) IEC 60825 International Standard Laser Regulations Radiation Safety Requirements for Class 3b and 4 Lasers Individuals shall not use lasers on humans unless under the supervision of a licensed practitioner of the healing arts and unless the use of lasers is within the scope of practice of their professional license. Individuals shall not be intentionally exposed to radiation above the maximum permissible exposure (MPE) unless such exposure has been authorized by a licensed practitioner of the healing arts. Exposure of an individual for training, demonstration or other nonhealing arts purposes is prohibited unless authorized by a licensed practitioner of the healing arts. Exposure of an individual for the purpose of healing arts screening is prohibited, except as authorized by the Texas Department of State Health Services. 23
Laser Regulations Exposure of an individual for the purpose of research is prohibited, except as authorized in research studies. Any research using radiation producing devices on humans must be approved by an Institutional Review Board (IRB) as required by the Code of Federal Regulations. The IRB must include at least one practitioner of the healing arts to direct use of the laser. These requirements apply to lasers that operate at wavelengths between 180 nm and 1 mm. Registration Requirements The registrant shall notify the agency in writing within 30 days of any increase in the number of lasers authorized by the Registration. An application for healing arts shall be signed by a licensed practitioner of the healing arts. An application for veterinary medicine shall be signed by a licensed veterinarian. Each new use of a Class 3b or Class 4 laser in the healing arts or for animal use shall be submitted to the agency within 30 days after beginning operation of the laser. Registration Continued No person shall make, sell, lease, transfer, or lend lasers unless such machines and equipment, when properly placed in operation and used, shall meet the applicable requirements. Each registrant shall inventory all Class 3b and Class 4 lasers in their possession at an interval not to exceed one year. The inventory shall be maintained for inspection and include: Manufacturer s Name Model and Serial Number of the laser Description of the laser Location of the laser 24
Registration Continued The Registrant shall maintain records of receipt, transfer, and disposal of Class 3b and Class 4 lasers for inspection to include: Manufacturer s Name Model and Serial Number of the laser Date of receipt, transfer, and disposal Name and address of person laser(s) received from, transferred to, or disposed by Name of individual recording the information Laser Regulations Each registrant or user of any laser shall not permit any individual to be exposed to levels of laser or collateral radiation higher than the Maximum Permissible Exposure (MPE) limits. Personnel operating each laser shall be provided with written instructions for safe use, including clear warnings and precautions to avoid possible exposure to laser or collateral radiation in excess of the MPE. Engineering Controls Measures necessary for controlling laser hazards normally concentrate upon making the beam path inaccessible, such as enclosing the laser in a box or controlled room to prevent unauthorized access. As this is not always possible, other Administrative and Engineering Controls are used to lessen the possibility of injury. The Safety Procedures necessary for any laser operation vary with 3 aspects: Laser hazard classification Environment where the laser is used (outside vs. inside a controlled area) People operating or within the vicinity of the laser beam (Desks in lab) 25
Performance Standards (Regulatory) Engineering Controls Protective Housing Each laser shall have a protective housing that prevents human access during the operation of the laser and collateral radiation that exceeds the limits of Class 1. Safety Interlocks A safety interlock, that shall ensure that radiation is not accessible above the MPE limits, shall be provided for any portion of the protective housing that by design can be removed or displaced during normal operation or maintenance, and thereby allows access to radiation above the MPE limits. Adjustment during operation, service, testing, or maintenance of a laser containing interlocks shall not cause the interlocks to become inoperative or the radiation to exceed MPE limits outside protective housing except where a laser controlled area is established. Safety Interlocks (pulsed laser) For pulsed lasers, interlocks shall be designed so as to prevent firing of the laser; for example, by dumping the stored energy into a dummy load. For continuous wave lasers, the interlocks shall turn off the power supply or interrupt the beam; for example, by means of shutters. An interlock shall not allow automatic accessibility of radiation emission above MPE limits when the interlock is closed. Either multiple safety interlocks or a means to preclude removal or displacement of the interlocked portion of the protective housing upon interlock failure shall be provided, if failure of a single interlock would allow human access to high levels of laser radiation. 26
Viewing Optics and Windows All viewing ports, viewing optics, or display screens included as an integral part of an enclosed laser or laser product shall incorporate suitable means, such as interlocks, filters, or attenuators, to maintain the laser radiation at the viewing position at or below the applicable MPE under any conditions of operation of the laser All collecting optics, such as lenses, telescopes, microscopes, endoscopes, etc., intended for viewing use with a laser shall incorporate suitable means, such as interlocks, filters, or attenuators, to maintain the laser radiation transmitted through the collecting optics to levels at or below the appropriate MPE. Normal or prescription eyewear is not considered collecting optics. Warning Systems Each class 3b, or 4 laser or laser product shall provide visual or audible indication during the emission of accessible laser radiation. For class 3b lasers and class 4 lasers, this indication shall be sufficient prior to emission of such radiation to allow appropriate action to avoid exposure. Any visible indicator shall be clearly visible through protective eyewear designed specifically for the wavelength(s) of the emitted laser radiation. If the laser and laser energy source are housed separately and can be operated at a separation distance of greater than two meters, both laser and laser energy source shall incorporate visual or audible indicators. The visual indicators shall be positioned so that viewing does not require human access to laser radiation in excess of the MPE. Controlled Area For class 3b lasers or class 4 lasers, a controlled area shall be established when exposure to the laser radiation in excess of the MPE or the collateral limits is possible. Each controlled area shall be posted by proper laser signage and access to the controlled area shall be restricted. 27
Indoor controlled areas For Class 4 indoor controlled areas, latches, interlocks, or other appropriate means shall be used to prevent unauthorized entry into controlled areas. Where safety latches or interlocks are not feasible or are inappropriate, for example during medical procedures, the following shall apply: All authorized personnel shall be trained in laser safety and appropriate personnel protective equipment shall be provided upon entry; A door blocking barrier, screen, or curtains shall be used to block, screen, or attenuate the laser radiation at the entryway. The level at the exterior of these devices shall not exceed the applicable MPE, nor shall personnel experience any exposure above the MPE immediately upon entry. At the entryway there shall be a visible or audible signal indicating that the laser is energized and operating at Class 4 levels. Class 4 Indoor Controlled Area For Class 4 indoor controlled areas, during tests requiring continuous operation, the individual in charge of the controlled area shall be permitted to momentarily override the safety interlocks to allow access to other authorized personnel if it is clearly evident that there is no optical radiation at the point of entry, and if necessary protective devices are being worn by the entering personnel. For Class 4 indoor controlled areas, optical paths from an indoor facility shall be controlled in such a manner as to reduce the transmitted values of the laser radiation to levels at or below the appropriate MPE and the collateral limits. Temporary Controlled Area When the removal of panels or protective covers and/or overriding the interlocks becomes necessary, such as for servicing, testing, or maintenance, and accessible laser radiation exceeds the MPE and the collateral limits, a temporary controlled area shall be established. 28
Nominal Hazard Zone (NHZ) Where applicable, in the presence of unenclosed Class 3b and Class 4 laser beam paths an NHZ shall be established. If the beam of an unenclosed Class 3b and Class 4 laser is contained within a region by adequate control measures to protect personnel from exposure to levels of radiation above the appropriate MPE, that region may be considered to be the NHZ. Key Control Each Class 3b and Class 4 laser shall incorporate a keyactuated or computer-actuated master control. The key shall be removable and the Class 3b and Class 4 laser shall not be operable when the key is removed. When not being prepared for operation or is unattended, the key will be removed from the device and stored in a location away from the machine. Additional Requirements for Safe Operation Infrared Laser The beam from an infrared laser shall be terminated in a fire-resistant material where necessary. Inspection intervals of absorbent material and actions to be taken in the event or evidence of degradation shall be specified in the operating and safety procedures. 29
Radiation Signage and Postings Radiation Signage and Postings Radiation Signage and Postings 30
Radiation Signage and Postings Radiation Signage and Postings Radiation Signage and Postings 31
Radiation Signage and Postings Audits/Inspections Lasers inspections are conducted by Radiation Safety to ensure regulatory compliance at intervals not to exceed 12 months. The inspections include a determination that all laser protective devices are labeled correctly, and functioning within the design specifications, and properly chosen for lasers in use; a determination that all warning devices are functioning within their design specifications; a determination that the controlled area is properly controlled and posted with accurate warning signs; a re-evaluation of potential hazards from surfaces that may be associated with beam paths; and additional surveys that may be required to evaluate the primary and collateral radiation hazard incident to the use of lasers. Records & Documentation Records Radiation Safety will maintain compliance records for regulatory review. Applicable records must be submitted to Radiation Safety upon request. Injury or Medical Event The Laser Safety Officer shall immediately seek appropriate medical attention for the individual and notify the agency by telephone of any injury involving a laser possessed by the registrant, other than intentional exposure of patients for medical purposes, that has or may have caused an injury to an individual that involves the partial or total loss of sight in either eye; or an injury to an individual that involves perforation of the skin or other serious injury exclusive of eye injury. 32
Regulatory Reporting The Laser Safety Officer shall, within 24 hours of discovery of an injury, report to the agency each injury involving any laser possessed by the registrant, other than intentional exposure of patients for medical purposes, that may have caused, or threatens to cause, an exposure to an individual with second or third-degree burns to the skin or potential injury and partial loss of sight. The Laser Safety Officer shall make a report in writing to the agency within 30 days and a notice to the individual shall be transmitted at the same time. The LSO shall also notify the agency of any medical event involving a patient as required. UNIVERSITY OF HOUSTON RADIATION SAFETY PROGRAM Purpose Protection of the university population, general public, and environment against radiation hazards associated with UH s possession, use, transportation, and disposal of radioactive material. Provide for compliance with TDSHS and other applicable radiation protection regulations. 33
Laser Safety Manual Purpose The purpose of the Laser Safety Manual is to assist personnel, students, and management in complying with the State Radiation Regulations and the Laser Safety Program. Intent This Laser Safety Manual is not intended to be an exhaustive or fully comprehensive reference, but rather a guide for Principal Investigators and Authorized Users. Authority The Laser Safety Manual is an enforceable component of the Radioactive Material Broad Scope License and Radiation Producing Devices Registrations under which the University of Houston is authorized. Training Requirements All PIs and Authorized Users of Class 3b and 4 lasers must attend and pass the laser safety training Testing- requires at least 70% to pass. This test is used to fulfill the requirement for users to demonstrate competence. Upon completion, be added to a sub-registration through an amendment. Online Annual Refresher Training. Testing requires at least 80% to pass Laser Safety Officer (LSO) duties Ensure that users of lasers are trained in laser safety, as applicable for the class and type of lasers the individual uses. Assume control and have authority to institute corrective actions including shutdown of operations when necessary in emergency situations or unsafe conditions. Laser Light Shows CDRH Requirements 34
LSO Duties Continued Ensure maintenance and other practices required for the safe operation of the lasers are performed. Ensure the proper use of protective eyewear and other safety measures. Ensure compliance with the laser requirements and with any engineering or operational controls specified by the registrant. Radiation Safety Responsibilities Radiation Safety Committee - Technical Expertise, Approve Facilities and Usage, Review Radiation Safety Program, Support RSO Authority Radiation Safety Officer and Staff - Radiation Safety Manuals, Audits and Lab Reviews, Incident Investigations, Health Physics Services, PI Consultations and Technical Support Principal Investigators Compliance, AUs Safety and Instruction Authorized Users - Work Safely and follow the Rules Administration Process (mainly for PIs) Laser Subregistration Application and Amendment Location changes Standard Operating Procedures Change services Laser purchasing, transfer, and disposal 35
Radiation Safety Violations Radiation Safety performs routine internal audits/inspections These help assure compliance with the UH Laser Registration and prevent a Notice of Violation (NOV) as a result of a state inspection If a violation is found by a state inspector during the inspection, the person committing the violation will be named on the NOV and not the RSO At UH, a Principal Investigator will be cited by Radiation Safety for violations which include any aspect of their subregistration conditions Chronic violations of subregistration conditions can jeopardize a Principal Investigator s authorization to use lasers Incident Notification Individuals working with radiation must assume the responsibility for their own safety and must ensure that their actions do not result in a hazard to others. In the event of a suspected or know exposure, immediately stop work and notify your Principal Investigator and the Radiation Safety Officer. If it is determined that there is an acute localized exposure, seek medical attention as soon as possible. Emergency Information EHLS office hours: Monday through Friday, 8:00 a.m. - 5:00 p.m. For assistance with a radiation emergency or incident during normal office hours call EHLS. In the event of an after hours radiation emergency, contact the UHDPS. EHLS maintains an on-call mechanism to provide expertise in the event of an after hours situation requiring assistance. Radioactive material spills and emergency information is available in the Radiation Safety Manual at http://www.uh.edu/ehls If you call after normal office hours about a non-emergency incident, you may leave pertinent information on EHLS telephone voicemail system. 36
Emergency Telephone Numbers EHLS Main Line (713) 743-5858 RSO/CLSO - Otu (713) 743-5867 ARSO/CLSO - Sangho (713) 743-5870 Health Physicist - Darla (713) 743-5860 Health Center (713) 743-5151 DPS (Emergency) 911 DPS (Non-Emergency) (713) 743-3333 Exam GOOD LUCK! 37