While beam hazards (exposure to the laser beam) are the most prominent laser hazards, other hazards pose an equal or possibly greater risk of injury or death. As laser technologies and applications expand further into our society, a greater number of associated or non-beam hazards will need to be considered for a safe work place.
The long list of associated hazards can be broken down into three hazard categories: Physical, Chemical, and Biological. Human factors pay a big part also. The LSO and laser user do not need to be an expert in these areas, but rather be aware that such hazards exist and be alert for them. Once identified, the appropriate safety professionals will perform a proper evaluation and advise on control measures mitigating the hazards.
Here is a partial list of non-beam hazards and some examples:
Physical Non-Beam Hazards
|Noise||Constant pinging of pulse laser|
|Pressure||Vacuum chamber, gas cylinders|
|Incoherent radiation||Broadband light source|
|High temperature||Ovens in lab|
|Low temperature||Cryogenic use|
|Trailing cables & pipes||Housekeeping|
|Sharp edges||Razor blades|
|Water- high-pressure||Cooling lines|
Chemical Non-Beam Hazards
|Toxic substances||Laser dyes|
|Dust & particulates||Cracked optics|
Biological Non-Beam Hazards
|Microbiological Organism||From target interaction|
|Viruses||Released from target interactions|
|Workstation layout||Hitting head on table shelves|
|Manual handling||Lifting of lasers|
|Person-machine interface||Robotic work|
|Shift patterns||Working too many or odd hours|
Non-beam hazards (NBH) are all hazards arising from the presence of a laser system, excluding direct exposure of the eyes or skin to a laser beam. These non-beam hazards, in some cases, can be life threatening, e.g. electrocution, fire, and asphyxiation.
All written WPC activities are designed to address non-beam hazards as well as beam hazards. The non-beam hazards can be a part of the laser activities or stand alone in separate activities. Due to the diversity of the NBH, the LSO will assist in identifying common types of non-beam hazards so that the Activity Lead may consult the appropriate safety professionals and other subject matter experts as needed.
Electrical equipment in general presents several potential hazards including: electrocution, resistive heating, ignition of flammable materials, and arc flash. Pub 3000 Chapter 8 Electrical Safety addresses use, maintenance, and service operations, as well as prevents or protects against possible misuse of equipment, and must be followed when electrical hazard is present. This article gives an overview what can be expected and considered when working with lasers.
The use of lasers or laser systems can present an electric shock hazard. These exposures can occur during laser set up or installation, maintenance, modification, and service, where equipment protective covers is removed to allow access to active components. A contact with energized electrical conductors contained in device control systems, power supplies, and other components is another way to receive an electric shock. With the use of large power supplies and repetitively pulsed lasers, there is a great potential for electric shock. Shocks usually happen when a person is working on equipment that is not properly grounded or has a large capacitor bank that was not discharged. Most injuries to personnel involving lasers are of this type.
Electric shock is a very serious opportunistic hazard where the occurrence and outcome are difficult to predict, and loss of life has occurred during electrical servicing and testing of laser equipment incorporating high voltage power supplies.
Protection against accidental contact with energized conductors by means of a barrier system is the primary methodology to prevent electric shock accidents.
The frames, enclosures and other accessible non-current-carrying metallic parts of laser equipment should be grounded. Grounding should be accomplished by providing a reliable, continuous metallic connection between the part(s) to be grounded. A presence of “Emergency Power Off’ switch will allow the elimination of electrical hazards during emergencies.
- Fluids should not be used or placed near the laser system
- The laser system should be labeled with the electrical rating, frequency and watts
- Proper grounding should be used for metal parts of the laser system
- Assume that all floors are conductive when working with high voltage
- Consider safety devices such as appropriate rubber gloves and insulating mats
- Make sure that the combustible components of the electrical circuit are short circuit tested
- Check that each capacitor is discharged, shorted and grounded before allowing access to the capacitor area
- Inspect capacitors containers for deformities or leaks
- Avoid wearing rings, metallic watchbands and other metallic objects when working near high voltage environment
- Prevent explosions in filament lamps and high pressure arc lamps
- Inspect regularly the integrity of electrical cords, plugs, and foot pedals
- Only qualified persons authorized to perform service activities should access a laser’s internal components
- Do not work alone
- When possible, only use one hand when working on a circuit
- Follow lockout/tag-out procedures when applicable
Heating of a conductor due to electric current flow increases with the conductor’s resistance. Unchecked and increasing resistive heating can produce excessive heat build-up and potentially damage/corrode system components. Additionally, touching one of these overheated components could result in a thermal burn to the user, maintainer or servicer. While laser system designers generally provide sufficient cooling for routine operations, equipment should be regularly checked for excessive resistive heating symptoms such as component warping, discoloration, or corrosion, and repaired as needed.
Electric Spark Ignition
Equipment malfunctions can lead to electrical fires. In addition, electrical sparks can serve as an ignition source in the presence of a flammable vapor. Sometimes, when working with devices that are not generally considered to be an ignition source they may cause smoke or charring without the presence of an actual flame. Under some situations where flammable compounds or substances exist, it may even be possible that smoke could be initiated by Class 3B lasers.
Fire extinguishers designed for electrical fires should be located in close proximity to the lasers. Components in electrical circuits should be evaluated with respect to potential fire hazards. Non-flammable materials must be used for enclosures, barriers or baffles.
An electrical arcing fault can produce an arc flash that includes intense radiant energy, high temperature air, a high-pressure wave, and high-velocity shrapnel from the electrical apparatus and housing. Causes of arc flash are human error while working on energized electrical equipment, and malfunction due to equipment age, poor maintenance, or poor design. Workers involved in arc flash may incur serious injury or death.
Non-Laser Radiation (NLR)
Non-laser radiation is any electromagnetic radiation, except laser radiation, emitted by a laser or laser system (e.g., excitation radiofrequency emissions, flashlamp light leakage, X-rays emitted by laser components). It is seldom a significant concern with a commercial laser product, but in some custom-built or very high power pulsed laser systems, it may present hazards that warrant additional control measures.
Laser-target interaction radiation is non-laser radiation emitted by material as a result of being exposed to a laser beam. The emission depends primarily on the laser irradiance at the target and the composition of the target material. One type of laser-target interaction radiation generated by processes involving irradiances above about 1012 W·cm-2 is plasma (ionized gas) radiation. Plasma is a form of matter that has been heated to a completely or partially ionized state.
X-ray radiation may be generated by electronic components of the laser system (e.g., high-voltage vacuum tubes-usually >15 kV) and from plasmas resulting from pulsed laser beams with a peak irradiance of the order of 1016 W·cm-2, or higher, that are focused on a target. Plasma radiation induced by extremely high power laser beams (>1018 W·cm-2) incident on specifically-designed targets may also accelerate ions to produce ionizing radiation, particularly neutrons, which in turn may lead to activation (induced radioactivity) in materials surrounding the target.
While high-voltage (>15 kV) vacuum tubes or electric-discharge lasers can produce X-rays, such devices are almost always appropriately shielded by manufacturers. Solid-state high-voltage components reduce or eliminate X-ray production from power supplies. Free electron lasers have much greater ionizing radiation issues, including X-rays, neutrons (at 10MeV and higher), muons (>1 GeV electron beams), synchrotron radiation, and activation product decay radiation.
Laser-related ionizing radiation must be controlled in accordance with the provisions listed in applicable federal, state, or local codes and regulations. A health physicist should be consulted.
Radiation other than that associated with the primary laser beam is called collateral radiation. Examples are X-rays, plasma, radio frequency emissions, and ionizing radiation. X-rays could be produced from two main sources in the laser laboratories: Electric-discharge lasers and high-voltage vacuum tubes of laser power supplies, such as rectifiers, thyratrons and crowbars.
Although laser radiation presents the chief hazard, it may not be the only optical hazard. Laser discharge tubes and pumping tubes may emit hazardous levels of ultraviolet radiation and should be suitably shielded. Particular care should be used with quartz tubes. Most lasers now use heat-resistant glass discharge tubes which are opaque in the UV-B (280 – 315 nm) and UV-C (100 – 280 nm) spectrum.
Laser-related UV sources must be suitably shielded so that personnel exposures are maintained within exposure limits specified by the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. High levels of shorter wavelength UV radiation can produce significant amounts of ozone, which will need to be exhausted if concentrations approach recognized exposure limits.
Sources of optical radiation that can cause eye injury and skin burn:
- UV from discharge tubes
- Visible / IR light from pumping lamps
- Blue light and UV emission from interactions between high power laser beam and target material
- Intense bright light and thermal emissions from laser welding
- Shield the optical radiation by proper enclosure
- Wear suitable PPE to protect eyes and skin
Interactions between very high power laser beams and target materials may in some instances produce plasmas. The plasma generated may contain hazardous UV emissions.
Radiofrequency (RF) and Microwave (MW)
Power supplies and other electrical equipment associated with some lasers are capable of generating intense electromagnetic (EM) fields. Power-frequency electric and magnetic fields (50 or 60Hz and harmonics) are produced by electrical power supplies, wiring, and circuit components for all lasers powered by alternating current. Some lasers contain radiofrequency (RF) excited components (e.g., plasma tubes, Q-switches) that can produce RF EM fields at frequencies into the microwave region. RF/microwave EM fields and lower frequency electric fields may be shielded with conductive materials (e.g., metals such as aluminum or copper). Shielding is more difficult for low-frequency RF and power-frequency magnetic fields, which may require the use of special shielding materials, such as ferrous alloys containing nickel or cobalt.
- Use protective features such as interlocks
- Use RF shielding, distance and time to minimize the hazard
A fire can occur when a laser beam (direct or reflected) strikes a combustible material such as paper products, plastic, rubber, human tissues, human hair, and skin treated with acetone and alcohol-based preparations. The risk of fire is much greater in oxygen-rich atmosphere.
The three components required for a fire to start are:
- A combustible material
- An oxidizing agent
- A source of ignition
Therefore, to reduce the risk of fire in laser applications, great care must be taken to keep these components physically separated from each other. In general, Class 3B lasers do not pose a fire hazard, while Class 4 lasers do.
Enclosure of Class 4 laser beams can result in potential fire hazards if enclosure materials are likely to be exposed to irradiances exceeding 10 W/cm2 or beam powers exceeding 0.5 W. Under some situations where flammable compounds or substances exist, it is possible that fires can be initiated by Class 3B lasers.
Opaque laser barriers (e.g., curtains) can be used to block the laser beam from exiting the work area during certain operations. While these barriers can be designed to offer a range of protection, they normally cannot withstand high irradiance levels for more than a few seconds without some damage (e.g., production of smoke, open fire, or penetration). Users of commercially available laser barriers should obtain appropriate fire prevention information from the manufacturer. Users can also refer to NFPA115 (Standard for Laser Fire Protection) for further information on controlling laser induced fires. The use of flame retardant materials is encouraged wherever applicable.
Operators of Class 4 lasers should be aware of the ability of unprotected wire insulation and plastic tubing to catch on fire from intense reflected or scattered beams, particularly from lasers operating at invisible wavelengths.
Barriers such as black photographic cloth or black paper products are used in a wide variety of applications for the purpose of containing the beam. These materials must not be used as the primary barrier for a high-powered Class 4 system. Beams of sufficient energy will burn this material quickly, causing smoke, fire, and breach of the barrier. The use of beam blocks and beam stops is highly encouraged in such situations.
- Maintain precise control of the laser beam
- Eliminate surfaces that can reflect laser beam
- Do not use combustible materials as enclosure material with Class 4 lasers or stored nearby
- Be prepared – have appropriate fire extinguisher in close proximity and easily accessible
Many metals or their oxides can represent fire or explosion hazards under certain circumstances, such as exposure to air, moisture, water, chemicals, shocks and impacts. Examples are alkali metals, aluminum, magnesium, titanium, hafnium, plutonium, thorium, uranium, and zirconium.
Extreme care should be taken during transfer and dispensing powders, in order to prevent the formation of dust or the introduction of oxygen.
High-pressure arc lamps, filament lamps, and capacitor banks in laser equipment should be enclosed in housings that can withstand the maximum explosive pressure resulting from component disintegration. The laser target and elements of the optical train that may shatter during laser operation should also be enclosed to prevent injury to operators and observers. Explosive reactions of chemical laser reactants or other laser gases may be a concern in some cases. There have been several reports of explosions caused by the ignition of dust that has collected in ventilation systems serving laser processes. The potential for such can be greatly minimized by good maintenance practice.
In addition, explosions can be caused by the beam from a Class 4 laser hitting a gas cylinder, regulator, or delivery hose.
Mechanical Hazards Associated with Robotics
Many industrial applications involve lasers employed with robots. Robots can punch holes in protective housing, damage the beam delivery system, or direct a laser beam at operators or enclosures. Robots typically have arms designed to operate at unique angles within a specified working envelope. However, mounting lasers to these arms may greatly extend the NHZ, thereby posing direct or reflected beam concerns at unanticipated locations. The installation should conform to recommendations contained in the latest version of ANSI IRIA Rl5.06: Standard for Industrial Robots and Robot Systems-Safety Requirements.
- Use surface interlock mats, interlocked light curtains, or non-rigid walls and barriers
- Confine the area of mechanical movement
- Provide sufficient warning to avoid mechanical injury
Certain lasers and associated electrical devices can generate painful and unpleasant noises at high frequency or repetitive rate which are harmful to the ears. Sources of this noise originate from the laser system itself, the fume extraction device, and the laser procedures. Some examples:
- Repetitive firing of high-energy pulsed lasers
- Discharging cycle of high capacitance capacitors
- Mechanical pumping of smoke evacuation systems
- Audible alarms or other noises associated with laser activities such as laser cleaning and drilling
Noise levels from certain lasers (e.g., pulsed excimer lasers), and their work environment, may be of such intensity that noise control may be necessary. This has occurred with certain excimer lasers and transversely-excited atmospheric (1EA) carbon dioxide lasers. In many cases, sound levels will not result in overexposure to noise, but may be a nuisance that should be addressed.
Hearing protection should be implemented where a noise level is above 90 dB for 8 hours per day or 110 dB for duration of 15 minutes according to the recommendation by OSHA standard 29CFR1910.95.
- Implement administrative controls to restrict individual exposure time
- Eliminate excessive noise by installing the noise absorbing material, where possible
- Employ visual warning instead of audible alarms
- Wear ear protectors where noise exceeds the recommended limits
Fiber Optic Fragment Hazards
Small lengths or particles of optical fiber material can pose a risk of irritation, infection, or injury, particularly when cleaving fibers during splicing operations. All personnel involved with this type of work need to be warned or trained on this hazard. The use of protective finger guards, gloves, or shields should be considered when performing cleaving operations. Adhesive tape can be used to pick up loose particles or splices during work operations. A good work practice is to collect discarded fibers in a suitable container to avoid subsequent embedding in clothing, skin, eye, or under the finger nails.
Always wear protective eyewear with side shields, even if you normally wear glasses, to prevent any flying shards from getting near your eyes.
Dispose of shards carefully in an appropriately labeled container for sharps. Use a black plastic mat for a work surface. The dark background will make it easier to see the fibers you are working with and handle them more carefully. Any broken fibers that fall on the mat are easily found for disposal.
- Always wear safety glasses with side shields and protective gloves. Treat fiber optic splinters the same as you would glass splinters
- Keep all food and beverages out of the work area or table where the fibers are cleaved and spliced. If fiber particles are ingested they can cause internal hemorrhaging
- Wear disposable aprons to minimize fiber particles on your clothing. Fiber particles on your clothing can later get into food, drinks, and/or be ingested by other means
- Never look directly into the end of fiber cables until you are positive that there is no light source at the other end. Use a fiber optic power meter to make certain the fiber is dark
- Do not touch your eyes while working with fiber optic systems until your hands have been thoroughly washed
- Put all cut fiber pieces in a properly marked container for disposal
- Place safety signs up in areas where fiber termination work is being performed
The term “nanoparticle” generally refers to particles <100 nm in at least one of its dimensions. The increasingly widespread use of nanomaterials has created concerns about the potential hazards posed by engineered nanoparticles. It appears that small size particles may have higher human risks than larger particles due to their increased reactivity potential. Toxicological studies suggest that some nanomaterials can be transported deep into the lungs and tissues, pass through blood-brain barrier, or translocate between organs. In addition, the greater surface to volume ratio associated with these particles can create greater chemical reactivity than the same material in larger particle sizes, increasing the relative toxicity and fire/explosion hazard presented by a given quantity of material.
Interaction of high energy femtosecond lasers with solid material can cause material blow off (ablation) of fast ions and atoms, as well as clusters and nanoaggregates of target material. The quality and quantity of that energy will determine the amount of ablated material as well as the average particle size. Processes that produce laser-generated nanoparticles must be engineered so as to avoid the entry of such particles into the body via inhalation, ingestion, or absorption processes.
Finally, a potential problem with the production of laser generated nanoparticles is the difficulty of assessing worker exposure and possible subsequent health effects. At the present, there are no occupational standards; appropriate metrics have not been determined; and measurement equipment is not generally available to properly document health effects.
These include compressed gases, dyes and solvents, and assist gases.
Sources of chemical hazards are:
- Dyes (the rhodamines) used in dye laser which are toxic compounds
- Flammable and toxic solvents used during dye preparation
- Hazardous gases (fluorine, hydrogen chloride) used in Excimer lasers
- Cryogenic fluids (liquid nitrogen) used in cooling systems of lasers
Hazardous gases (e.g., chlorine, fluorine, hydrogen chloride, and hydrogen fluoride) are used in some laser applications. All compressed gases having a hazardous material information system (HMIS) health, flammability, or reactivity rating of 3 or 4 must be contained in an approved and appropriately exhausted gas cabinet that is alarmed with sensors to indicate potential leakage conditions. Procedures must be developed for safely handling compressed gases. Appropriate safety measures should be implemented to avoid the following safety issues associated with compressed gases:
- Working with a free-standing cylinder not isolated from personnel
- Failure to protect open cylinders (regulator disconnected) from atmosphere and contaminants
- No remote shutoff valve or provisions for purging gas before disconnect or reconnect
- Labeled hazardous gas cylinders not maintained in appropriate exhausted enclosures
- Gases of different categories (toxic, corrosive, flammable, oxidizer, inert, high pressure, and cryogenic) not stored separately in accordance with OSHA and Compressed Gas Association requirements
- Sensors must be installed in hazardous gas cabinets and other locations as appropriate, including exhaust ventilation ducts
- Exhaust ductwork should be of rigid construction, especially for hazardous gases
- Sensors and associated alarm systems should be used for toxic and corrosive chemical agents such as halogen gases. Sensors should always be able to detect the hazardous gas in a mixture of emitted gases (i.e., fluorine versus hydrogen fluoride)
- Gas detection systems must be properly shielded to minimize susceptibility to electromagnetic interference (EMI)
Cryogenic liquids (especially liquid nitrogen) may be used to cool the laser crystal and associated receiving and transmitting equipment. These liquefied gases are capable of producing skin burns and may replace the oxygen in small unventilated rooms.
- The storage and handling of cryogenic liquids must be performed in a safe manner.
- Insulated handling gloves of quick removal type should be worn
- Clothing should have no pockets or cuffs to catch spilled cryogenics
- Suitable eye protection must be worn. If a spill occurs on the skin, flood the skin contact area with large quantities of water
- Adequate ventilation must be present in areas where cryogenic liquids are used
Dyes and Solvents
Laser dyes are complex fluorescent organic compounds that, when in solution with certain solvents, form a lasing medium for dye lasers. Certain dyes are highly toxic or carcinogenic. Since these dyes frequently need to be changed, special care must be taken when handling and preparing solutions from them, and when operating dye lasers. An MSDS for dye compounds must be available to all appropriate workers.
The use of dimethylsulfoxide (DMSO) as a solvent for cyanine dyes in dye lasers should be avoided if possible. DMSO aids in the transport of dyes through the skin and into the blood stream. Replace with another solvent if possible. Low permeability gloves should be worn by personnel any time a situation arises where contact with the solvent may occur.
Dye lasers containing at least 100 milliliters of flammable liquids must be in conformance with the provisions of the NFPA (NFPA 30 and 45), and the NEC [Article 500- Hazardous (classified) Locations]. Laser dyes must be prepared in a laboratory fume hood. Dye pumps and reservoirs should be placed in secondary containment vessels to minimize leakage and spills in conformance with NFPA 115.
- Consult the Material Safety Data Sheet for the chemical in use
- Wear PPE such as lab coats, gloves and goggles when handling the chemicals
- Store the chemicals in a proper place
- Provide adequate ventilation
- Follow the clean-up and waste disposal procedures for any chemical spills
Lasers are capable of heating specified areas very rapidly and they are therefore suitable for certain surface heat treatment and surfacing applications. These include laser hardening, alloying and cladding. Assist gases (or process gases) are used at the point in the process where the laser interacts with the material.
Choice of assist gas
- The choice of assist gas is extremely important and can have a significant effect on the resulting process quality and productivity
- When cutting mild steel, oxygen can enable higher cutting speeds and greater thickness at lower pressure and flow rate than nitrogen
- Nitrogen and other inert assist gases prevent surface oxidation, producing a higher quality finish which requires minimal preparation for other fabrication processes (such as welding) and surface treatment
- Lasers can cut a wide range of materials including ferrous and non-ferrous metals, plastics, wood and ceramics. The choice of assist gas should be made with regard to the material being cut
- In a plasma spraying process, inert gases are needed as plasma gas and carrier gas (for the powder). Mostly plasma gases are Argon, Helium, Nitrogen and Hydrogen
- Nitrogen can be used as an assist gas for laser marking or engraving on any type of material.
For a risk assessment and implementation of safety control measures with the use of assist gasses, a chemical safety specialist should be consulted.
Oxygen-deficiency detection controls may be needed to detect a lack of breathable air in a space that could be occupied by someone. This situation may be the result of inadequate ventilation or displacement of air by a gas or process byproduct. Guidelines for oxygen-deficiency detection must be developed on a case-specific and hazard basis through WPC Activity reviews or risk assessments conducted using the Oxygen Deficiency Hazard calculator (See Safe Handling of Cryogenic Liquids, Work Process C, Oxygen-Deficiency Risk Assessment), Chapter 13 Gas Safety.
These include LGAC and infectious materials.
Laser Generated Air Contaminants (LGAC)
Air contaminants may be generated when certain Class 3B and Class 4 laser beams interact with matter. The quantity, composition, and chemical complexity of the LGAC depend greatly upon target material, cover gas, and the beam irradiance. While it is difficult to predict what LGAC may be released in any given interaction situation, it is known that contaminants, including a wide variety of new compounds, can be produced with many types of lasers. When the target irradiance reaches approximately 107 W/cm2, target materials including plastics, composites, metals, and tissues may liberate carcinogenic, toxic and noxious airborne contaminants. The amount of the LGAC may be greater for lasers that have most of their energy absorbed at the surface of the material.
Some examples include:
- Polycyclic aromatic hydrocarbons from burns on poly (methyl methacrylate) type polymers
- Hydrogen cyanide and benzene from cutting of aromatic polyamide fibers
- Fused silica from cutting quartz
- Heavy metals from etching
- Benzene from cutting polyvinyl chloride
- Cyanide, formaldehyde and synthetic and natural fibers associated with other processes
Exposure to these contaminants must be controlled to reduce exposure below acceptable OSHA permissible exposure limits. The material safety data sheet (MSDS) may be consulted to determine exposure information and permissible exposure limits.
In general, there are three preventive measures available: exhaust ventilation, respiratory protection, and isolation of the process. The priority of control requires that engineering controls be used as the primary control measure, with respiratory protection (and other forms of PPE) used as supplementary controls.
- Exhaust Ventilation. Whenever possible, recirculation of plume should be avoided. Exhaust ventilation, including use of fume hoods should be used to control airborne contaminants. Exhaust ventilation systems (including hoods, ducts, air cleaners, and fans) should be designed in accordance with recommendations in the latest revision of ACGIH Industrial Ventilation and ANSI Z9.2: Fundamentals Governing the Design and Operation of Local Exhaust Systems.
- Respiratory Protection. Respiratory protection may be used to control brief exposures, or as an interim control measure until other administrative or engineering controls are implemented. If respiratory protection is utilized, it should comply with the provisions specified in 29 CFR 1910.134.
- Process Isolation. The laser process may be isolated by physical barriers, master-slave manipulators, or remote control apparatus. This is particularly useful for laser welding or cutting of targets such as plastics, biological material, coated metals, and composite substrates.
The most effective means of reducing concentration of LGAC is by employing proper ventilation and air filtration systems. Local exhaust ventilation (LEV) system can effectively capture the air contaminants in close proximity to an emission source. A LEV system is designed to draw contaminated air (LGAC) from a laser process through a partial enclosure or hood at the source of lasing site. The contaminated air is exhausted outside the laser workplace through particulate filtration process. A typical LEV system in an industrial setting employs five major components: a hood or enclosure to capture the LGAC, ducts to carry the contaminated air, suitable fan to provide the airflow, filters to absorb the contaminants in the air, and stack to exhaust the cleaned air.
However, no LEV systems are 100% efficient in capturing all dusts, vapors and fumes in the air. General ventilation should be provided to reduce the concentration of the air contaminants not removed from the LEV.
Control of LGAC includes, but not limited to, the following work practices and preventive measures:
- Modify the process or work practice to produce less fume
- Restrict the number of workers present in the hazardous fume zone/laser controlled area
- Limit the duration of exposure
- Perform decontamination prior to taking part in other activities. Washing hands is a good protection of LGAC, a work uniform should be changed daily
- Food, beverage, and cigarettes are not allowed in the NHZ
- Provide respiratory protection training
- If laser generates biological agents, infection control should be part of the training
- Ensure staff uses the PPE properly and effectively
- Implement preventive maintenance schedule for exhaust ventilation systems
- Good communication between management and workers is essential
A professional industrial hygienist should be consulted for the requirements of ventilation system.
Infectious materials, such as bacterial and viral organisms, may survive beam irradiation and become airborne. To prevent inhaling infectious laser plums it is recommended the use of high filtration (0.1 micron) masks along with a high-efficiency smoke evacuation system.
There may be ergonomic hazards associated with the operation, maintenance, or service of the laser system. The ergonomic hazards such as awkward postures, poor workstation layout, worker-machine interface, manual handling techniques, and area illumination could contribute to improper actions if not addressed. Painful arm, hand, and wrist injuries (e.g., carpal tunnel syndrome) may result from repetitive motions occurring during the use of some laser products.
Ergo-ophthalmological issues such as glare, startle reactions, afterimages and temporary flash blindness have been reported in the laser environment as distractions that lead to other primary or secondary effects of a more serious biological nature.
Limited Work Space
There is limited work space or area in many laser system installations. Such limited work space can present a problem while working near or around mechanical setup or high voltage. There should be sufficient room for personnel to turn around and maneuver freely. This issue is further compounded when more than one type of laser is being operated at the same time. The presence of wires and cables on the floor of limited work areas can create trip and slip hazards.
Laser facilities can pose hazard to laser workers due to obstacles, ambient lighting, confined workplaces, indoor temperature and humidity.
- Provide adequate lighting in the laser controlled area, or luminescent devices on equipment corners, switch locations, and aisles, etc.
- Remove any obstacles inside the nominal hazard zone
- Install the cables, gas tubing or water hoses in a proper way
- Arrange the laser workplace to have a safe working environment
- Avoid condensation on laser equipment, such as optical components, electrical devices, etc.
- Provide suitable room temperature for the operation of laser equipment
The LSO will assist in evaluating hazards and controls for non-beam hazards and consult with other subject matter experts as needed.