8.1 RADIATION SAFETY
At this time, radioactive materials are not to be used in the Cole Science Center.
This section describes requirements for personnel protection from laser radiation and other associated hazards. These requirements are designed to comply with the Massachusetts Department of Public Health (DPH) Code 105 CMR 121.000, Rules and Regulations Relative to the Use of Laser Devices or Equipment to Control the Hazards of Laser Rays and Beams (pdf)
This document delineates the requirements for registration and safe use of high power lasers and laser systems. All operations or research involving the use of lasers must be conducted in such a manner as to ensure that personnel exposure to laser radiation is below the maximum levels specified in 105 CMR 121.600. Further, all operations involving the use of high-power lasers shall be planned and executed using the recommendations of the American National Standards Institute Z136.1 - 2000, "Standard for the Safe Use of Lasers." Many of those recommendations are incorporated into this document. ANSI Z136.1 is available from the lab manager.
The following is a summary of requirements for laser use.
|Registered with RSO||2||3a||3b||4|
|Laser Safety Training||3a||3b||4|
|Laser Safe Operating Protocol||3b*||4|
*If invisible to the eye, and if a cw laser, with visible beams > 15mW of power.
8.2.1 Laser Classification
Lasers are classified according to the definitions of Section 3.3 of ANSI Z136.1. Classification and labeling of commercially purchased lasers is the responsibility of the manufacturer. In addition to meeting the general requirements of this chapter, lasers must meet specific requirements based on laser class. Only lasers fabricated on-site would require classification by the investigator, which requires approval of the radiation safety officer.
Laser classification and entry controls are summarized below.
Class 1 denotes exempt lasers or laser systems that cannot, under normal operating conditions, produce a hazard. Equipment such as laser printers that completely enclose the laser and laser beam are normally specified as Class 1.
Class 1 lasers must be labeled, but are exempt from other requirements.
Class 2 denotes low power visible radiation lasers or laser systems. Visible cw HeNe lasers above Class 1, but not exceeding 1 mW (milliwatt) radiant power, are common examples of this class. Because of the normal human aversion or blink response, these lasers normally do not present a hazard. Class 2 lasers may present a hazard if viewed directly for extended periods of time (like many conventional light sources).
Class 2 lasers must be labeled and registered with the radiation safety officer, but are exempt from other requirements. The warning label or sign shall caution users to avoid staring into the beam or directing the beam toward the eye of individuals, and shall be placed on or near the laser in a conspicuous location.
Class 3a denotes lasers or laser systems that normally would not produce a hazard if viewed for only momentary periods with the unaided eye. They may present a hazard if viewed using collecting optics. Visible cw HeNe lasers above 1 mW but not exceeding 5 mW radiant power are examples of this class.
Class 3a lasers must be operated in a location where access to the beam can be controlled. The potential for viewing of the direct or specularly reflected beam must be minimized. The operator of the laser shall inform personnel entering the area of the presence of the laser beam and the precautions they need to follow.
Class 3b denotes lasers or laser systems that can produce a hazard if viewed directly. This includes intrabeam viewing or specular reflections. Except for the higher power Class 3b lasers, this class laser will not produce hazardous diffuse reflections. Visible cw HeNe lasers above 5 mW but not exceeding 500 mW radiant power are examples of this class.
Class 3b lasers must be used in areas where entry by unauthorized personnel can be controlled. Entry into the area of personnel untrained in laser safety may be permitted by the laser operator if they are instructed as to safety requirements and are provided with protective eyewear, if required.
Class 4 denotes lasers or laser systems that can produce a hazard not only from direct or specular reflections, but also from a diffuse reflection. In addition, such lasers may produce fire and skin hazards.
Class 4 lasers must be operated by authorized users in areas dedicated to their use. Fail-safe interlocks must be used to prevent unexpected entry into the controlled area, and access shall be limited by the laser operator to persons who have been instructed as to safety procedures and who are wearing proper laser protection eyewear (if required by written procedures) when the laser is capable of emission. Authorized operators are responsible for providing information and safety protection to untrained personnel who may enter the laser controlled area as visitors.
For pulsed systems, interlocks shall be designed so as to prevent firing of the laser 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 by means of shutters.
Manufacturer classifications are based on the level of laser radiation accessible during intended operation of the laser. The hazard may be greater, and therefore require additional controls, when maintenance or service is being performed.
188.8.131.52 Responsibilities of Laser Investigators
Investigators using lasers are responsible for assuring their safe use in their area or lab. Specific responsibilities include:
184.108.40.206 Responsibilities of Laser Users
The individual user is responsible for:
220.127.116.11 Responsibilities of the Laboratory Manager
18.104.22.168 Responsibilities of the Safety Committee
8.2.3 Laser Registration
Prior to purchase of a Class 2, 3a, 3b, or Class 4 laser, and for existing lasers, a registration form (Appendix 8-A) must be submitted.
8.2.4 Laser Safe Operation Protocol
A safety committee-approved Laser Safe Operating Protocol (LSOP) is required for all Class 3b and 4 lasers. The committee may, however, recommend or require a LSOP for any laser or laser application where it is deemed necessary for ensuring adequate safety controls.
The investigator prepares the LSOP. The LSOP shall include all information outlined in Appendix 8-B and shall receive safety committee approval before the laser is operated.
8.2.5 General Safety Requirements
8.2.6 Laser Safety Training
All users of Class 2, 3a, 3b, and 4 lasers shall receive training by the investigator and read "Laser Safety Training" (see Appendix 14). All users of Classes 3b and 4 lasers shall be re-certified in laser safety at intervals not to exceed two years.
Upon completion of training, the investigator and user must complete an "Authorized Laser User Certification" form (Appendix 8-D).
8.2.7 Laser Medical Surveillance
All investigators and users who are routinely engaged in work where they may be exposed to laser radiation from a class 3b or 4 laser must participate in the laser medical surveillance program.
The purpose of laser medical surveillance is twofold. The first purpose is to establish a baseline of ocular conditions before exposure to laser radiation. The second purpose is to detect and document, as early as possible, ocular damage in the event of a suspected exposure incident. Both purposes serve to assess the effectiveness of control measures and to promptly institute appropriate therapeutic measures.
Laser medical surveillance includes a preliminary baseline eye exam. Additional eye exams are required immediately in the event of exposure or suspected exposure to laser radiation above the Maximum Permissible Exposure (MPE) established in 105 CMR 121.600 (pulse and wavelength dependent). An eye exam may be required upon termination of laser work or upon termination of employment at Hampshire College.
Investigators should contact the environmental health and safety office to schedule baseline eye exams and to report suspected exposures above the MPE.
8.2.8 Laser Warning Signs
Laser warning signs must meet the standards of ANSI Z136.1. Class 1 lasers do not require a sign. The word CAUTION shall be used with all Class 2 and Class 3a lasers. The word DANGER shall be used with all Class 3b and Class 4 lasers. Signs, including the appropriate precautionary statements detailed in ANSI Z136.1, must be described in the LSOP.
All warning signs and labels shall be displayed conspicuously in locations where they best serve to warn individuals of potential safety hazards. Normally, warning signs are posted at entryways (e.g., on doors) to laser controlled areas.
Warning labels are affixed to the lasers in a conspicuous location. The laser investigator should remove laser warning signs if the laser has been removed from the room or area.
8.2.9 Safe Laser Practices
The following control measures are recommended as a guide to safe laser use. If any of these control measures cannot be accomplished, the LSOP must describe alternative controls to provide comparable protection. These practices are taken from ANSI Z136.1. Refer to that document for additional details.
The purpose of controls is to reduce the possibility of exposure to the eye and skin to hazardous laser radiation and to control other hazards associated with operation and maintenance of laser devices.
Engineering controls (physical features incorporated into the design or installation of the laser system) are the preferred method of control. If engineering controls are not feasible, then administrative and procedural controls and personal protective equipment should be used.
Administrative and Procedural Controls
Recommended Work Area Controls
Recommended Laser Use Controls
Laser Protective Equipment
Normally, all persons who work in areas where there is radiation from Class 3b or Class 4 lasers must wear approved laser eyewear if the potential exists for exposure in excess of the MPE. Exceptions may be approved if wearing protective eyewear produces a greater safety hazard than when it is not worn. Exceptions shall be described in the LSOP.
The eyewear to be used will depend on the wavelength(s) and intensity of the accessible radiation. Keep in mind:
In some cases, other protective equipment, such as clothing to protect the skin, may be required. Such requirements must be addressed in the LSOP.
8.2.10 Associated (Non-Beam) Laser Hazards
Depending on the type of laser used, associated hazards other than those from beam radiation may be involved. Such hazards, if they exist, must be addressed in the LSOP.
1. Vaporized target material: contaminants may include carbon monoxide, ozone, lead, mercury, and other metals.
2. Gases from flowing gas lasers or byproducts of laser reactions such as fluorine, hydrogen cyanide, and many others.
3. Gases or vapors from cryogenic coolants.
Chemicals, including dyes and solvents, from certain dye lasers have been shown to be carcinogenic, toxic, or otherwise hazardous.
Cryogenic liquids, such as liquid nitrogen or hydrogen, may cause burns.
The potential for electrical shock is present in most laser systems. Pulsed lasers utilize capacitor banks for energy storage and cw lasers generally have high voltage DC or RF electrical power supplies.
The potential exists for explosions at capacitor banks or optical pump systems during the operation of some high power lasers. Explosive reactions of chemical laser reactants or other gases used within the laser laboratory could cause damage to equipment or injury to personnel.
The use of jewelry (watches, rings etc.) is often an overlooked source of exposure to a beam reflected by a mirror-like surface.
Either direct or reflected UV radiation from flash lamps and cw laser discharge tubes may cause eye injury. Usually, UV radiation is a problem only when quartz tubing or windows are used.
Visible Radiation (non laser)
High luminance radiation emitted from unshielded pump lamps may cause eye injury. Potentially hazardous X-rays may be generated from high voltage (over 15kV) power supply tubes.
8.2.11 Laser Accidents
As with driving a car, accidents with lasers can happen to anyone, despite the operator's experience. Of course, adherence to safety precautions reduces the chance of an accident occurring. In most cases, accidents occur because proper eyewear was not worn. All suspected overexposure to laser radiation must be reported immediately to the investigator; in most cases medical examination will be required. An accident report, available from the lab manager, must also be completed.