The University of the Virgin Islands
Draft LASER SAFETY PLAN
SECTIONS:
I.
Laser Classification
II.
Eye Protection
III.
Skin Protection
IV.
Respiration
Hazards
V. Non-Beam Hazards
VI. Outline of Protective
Measures in the Use of Lasers
VII.
Laser Safety Officer
VIII. Important Response Agencies Addresses and Phone Numbers
I. Laser Classification
A laser produces an intense beam of
light of a single wavelength (or color) and frequency. Laser intensity varies from low power (Class
1, 2, and 3A lasers), to medium (Class 3B) to high power (Class 4). The
American National Standards Institute (ANSI) classifies lasers into categories
and gives guidelines on laser safety in the standard Z136.1. Following are
laser categories as outlined by ANSI.
·
Class
1: Cannot emit laser
radiation at known hazard levels.
·
Class
2: Low-power visible lasers.
Emit laser radiation above Class 1 levels and radiant power not above 1mW. The
human aversion reaction to bright light will protect the person from this low
level. Example: a supermarket laser scanner.
·
Class
3A: Intermediate-power
lasers. Only hazardous for intrabeam viewing, which means
looking directly into the laser beam path. Some limited controls are
usually recommended. Example: a helium-neon laser used in the construction
industry.
·
Class
3B: Moderate-power lasers.
Not generally a fire hazard and not capable of producing a hazardous diffuse
reflection, except in instances of intentional staring at distances close to
the diffuser. Specific controls and
safety requirements are recommended.
·
Class
4: High-power lasers.
Hazardous to view under any condition (directly or diffusely scattered).
Potential fire hazard and a skin hazard. Significant controls are required for
Class 4 laser facilities. Example: an Excimer laser operating in the
ultraviolet.
II. Eye Protection
Although the University presently does not possess
high-power lasers, it is important to include broad guidelines for safety in
using the low-powered lasers we have and all lasers in general. The following
excerpts from CRC Hawk of Laboratory Safety describe safety measures,
which focus on eye protection (primarily) but also
skin protection and protections against electrical shock, ozone generation and
respiratory hazards resulting from lasers and their power suppliers. These
devices represent a burn hazard, an eye hazard, and an ignition source for
flammable liquid vapors.
· Never look directly into its light source.
· Never illuminate skin with its light source.
· Keep papers and other combustibles away from laser.
The first concern in laser protection continues to be the eyes. Full protection of the eyes means not only from the direct beam but also from the reflection of the beam off of surfaces. A laser's eye-damaging ability varies depending on which area of the light spectrum it is generating. The ultraviolet radiation laser (180-400nm) causes corneal burns. Lasers in the near-infrared region (780-1800nm) cause retinal damage. These are usually Class 2, 3A, 3B and 4 lasers. Protection for the eyes requires goggles made of the proper protective material and which are so fitted in order that stray light cannot come in from any angle. It is imperative that personnel do not look down the barrel of any laser when the laser is operating or, in the case of a high-energy laser, when there is a charge on the power supply capacitors.
Helium-neon lasers are used commonly and more carelessly today. It is emphasized
that even low output helium-neon lasers can cause eye damage The helium-neon
gas laser output at 6328Å (632.8 nanometers) is effectively, filtered using the BG-18 glass. However, this and other glass lasers, together with junction diode lasers, generate wavelengths in the infrared, which, because of their fairly low outputs, do not cause any strong sensation when absorbed directly into the eye. Sufficiently large doses, however, can cause irreparable damage to the eye and as much caution should be exercised with these lasers as with the high-energy lasers. With the argon laser, protective glasses plus screens of amber Plexiglas or ruby-tinted plastic are used for eye protection.
The carbon dioxide laser with its invisible beam is especially hazardous. The target area must be isolated and hands, articles of clothing, and other objects should be kept out of the target area. Two 2-mm plates of fused quartz with an optical density over 35, will protect against the eye hazards of the invisible beam. For ultraviolet lags, special ultraviolet protective glasses are required. The C02 laser, with its output of 106,000Å (10,600 nm) and energy above the kilowatt range, may cause burns of the surface of the eye or cornea since at this wavelength almost everything absorbs the laser beam.
Always wear protective goggles that offer protection against the implored wavelength of the equipment. Recently, "all purpose" protective goggles with special filters have been proposed, but as yet, there is not enough data regarding the goggles to recommend them. Therefore, as a rule, all-purpose goggles should not yet be used.
According to the
ANSI standard, protective eyewear shall exhibit a damage threshold for a
specified exposure time (typically 10 seconds). The eyewear shall be used in a
manner so that the damage threshold is not exceeded in the worst case exposure
situation.
It is recommended that personnel not work in the dark since the difference in eye acceptance area between being in the dark and in the light is 16:1. In the dark the open pupil makes the eye more vulnerable. But, this situation makes the beam far more noticeable and easier to avoid. Typically, the room is not darkened if not it is not necessary for the experiment.
III. Skin Protection
Another concern in personal protection with the use of the high-energy laser is the exposure of the skin. The direct incidence of high-energy lasers may cause considerable damage to the skin, especially where it is pigmented. The high-powered lasers, Class 3B and 4, can also cause electrical shock and skin burns. A skin cover, like opaque gloves and tightly woven fabrics, and or a "sun screen" may be recommended. At present it is known that even low-energy densities of 0.23 joules of exit energy and 15 - 20 joules/cm2 energy density in a target area of 0.004 cm2 produce significant reaction in the skin. Black felt or leather gloves or felt coverings can be used on the hands. The face should be turned away from the target area. (Note also that laser radiation may ignite combustibles.)
IV. Respiration Hazards
Air contamination can be a problem, especially as it relates to the use of liquid nitrogen coolants, nitrogen purges, spectroscopy and fragments from the laser plume. Liquid nitrogen produces burns when handled in a careless manner.
Ozone is produced at times about the flash lamps and concentrations of ozone could build up with high repetition rate lasers. Proper ventilation is required.
V. Non-Beam Hazards
Once protective eyewear is selected, other safety issues—called non-beam hazards—need consideration.
- A potential explosion hazard may occur from the buildup of high pressures of gases in the flash lamp when it is fired.
- Electrical shock or electrocution may occur from contact with exposed utility power. Exposures can occur during setup, installation, maintenance and service of the laser.
- Fire is a potential hazard with all laser systems. The flame-retardant materials must be stationed nearby.
VI. Outline of Protective Measures in the Use of Lasers
Safety measures in a system for the protection of the operating personnel include:
1. Safety Signs must displayed in
the immediate vicinity of the laser, in the room with the laser, and in the
vicinity of the target. These signs shall warn of the danger of laser light and
these statements should be clearly viewable. “Do not look to the LASER with
your eyes.” “Protect your eyes from
LASER light.”
2. A warning light system initiated on charging of any high-energy laser in the laser room, which causes red lights to flash intermittently in the laser room and in any adjoining rooms, and a large warning sign outside the laboratory to be illuminated. In addition, a muted bell system, which commences chiming on charging of the laser capacitor banks and continues until the laser is discharged.
3. Black curtains or screens which maybe pulled around the laser stations to screen personnel from the laser flash.
4. Use appropriate personal protective equipment, including safety glasses/goggles, gloves, respirators, etc., as required. Use of specifically designed antilayer flash goggles for that specific laser type for personnel working with particular laser.
5. Avoidance of specular surfaces by rough finishing of the walls and painting with flat charcoal black paint.
6. Proper air conditioning of the rooms.
7. Work shall be performed in hoods where required when either noxious fume is produced or airborne contaminants are released to the air.
VII. Laser Safety Officer
The Laser Safety Officer (LSO) is responsible for monitoring and enforcing the control of laser hazards, which includes operation and safety procedures and maintenance and service plans.
- Operation: Tasks necessary to assure
operations of the laser. Lasers and
laser systems are to be classified on the basis of the level of the laser
radiation accessible during intended use.
- Maintenance: Tasks necessary to assure
routine performance of the laser.
The manufacturer of each type of laser should supply instructions
for safe operation.
- Safety: LSO must provide safety training to ensure employee and student safety.
The
current Laser Safety Officer:
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VIII. Important Response Agencies Addresses
and Phone Numbers
Fire Emergency 911
Police Emergency 911
University of the
University of the
Government of the Virgin Islands, Department of Planning
& Natural Resources, Environmental Protection,
Government of the Virgin Islands, Department of Planning
& Natural Resources, Environmental Protection,
Environmental Protection Agency, Federal Building
Room 142,
Centers for Disease Control and
Public Inquiries: 1-800-311-3435 or 404-639-3534
National Response Center, c/o United States Coast Guard (G-OPF), 2100 2nd Street, Southwest - Room 2611 Washington, DC 20593-0001 Chemical/Biological Hotline: 1-800-424-8802
Occupational Safety & Health Administration, Region 2, Regional Office for U.S. Virgin Islands, 201 Varick Street, Room 670, New York, New
York 10014 212-337-2378
Written by Ann Marie Dublin and Eugenia Somerall-Sello
Reviewed by Paul L. Kahn, On-Scene Coordinator,
Environmental Protection Agency
Web Page Designed by Eugenia Somersall-Sello
Last Updated: August 24, 2006