9.1 -- Laser Safety

PURPOSE AND SCOPE

The purpose of the Laser Safety Program is to establish Temple University's policy for the standardized and safe use of all clinical and research lasers within the university. This program is primarily based on guidance from the American National Standards Institute (ANSI) Z136 series, specifically ANSI Z136.1 – American National Standard for Safe Use of Lasers (2022)

The Temple University Laser Safety Program outlines documentation, responsibilities, and protocols to ensure the safe operation and hazard control of all Class 3B and Class 4 lasers used at the university. It is designed to provide reasonable and comprehensive guidance for safe laser use.

This chapter details the classifications of lasers and the corresponding safety controls required for each class. Compliance with the Laser Safety Program includes (but is not limited to): laser classification and hazard assessment, assignment of specific responsibilities, laser registration, development of Standard Operating Procedures (SOPs), and laser safety training for users. All expectations and requirements are explained in this chapter.

RESPONSIBILITIES

Environmental Health and Radiation Safety Department (EHRS)

The Environmental Health and Radiation Safety (EHRS) office is responsible for implementing the Laser Safety Program and ensuring that laser operations are conducted in accordance with approved policies and applicable regulatory requirements. The Director of EHRS, or their designee, is authorized to suspend, restrict, or halt laser operations if, in their judgment: 1) The laser is not being operated in accordance with the approved Standard Operating Procedure (SOP); 2) The laser is being used in a manner deemed unsafe; 3)The laser is being operated in violation of Temple University policies.

The Director of EHRS may require corrective actions to ensure compliance with both university policy and federal regulations.

EHRS is responsible for:

• Establishing and maintaining policies and procedures to control laser hazards.
• Reviewing and approving (disapproving) of the laser installation facilities and Class 3B/Class 4 laser equipment prior to use.
• Approving SOPs and related procedures for Class 3B and Class 4 lasers, including administrative and procedural controls.
• Assisting with the evaluation and control of laser-related hazards.
• Assisting with laser classification or verification of laser/laser system classifications.
• Assisting in the calculation and selection of appropriate laser safety eyewear.
• Reviewing signage and labeling for laser areas and equipment.
• Providing laser safety training for all laser personnel.
• Determining personnel categories requiring medical surveillance
• Maintaining records of lasers and authorized laser operators.
• Participating in investigations of laser-related incidents or accidents.
• Conducting periodic audits of departmental laser safety programs.
• Participating in the activities of the Laser Safety Committee.

Clinicians/Principal Investigators (PI)

Clinicians and Principal Investigators who oversee Class 3B and Class 4 lasers are responsible for the following:

• Submit a Laser Registration Form to EHRS for each Class 3B or Class 4 laser (including both commercial and homemade units).
• Develop and provide a written Standard Operating Procedure (SOP) for each laser operation involving a Class 3B or Class 4 laser, in accordance with ANSI Z136.1-2022. Each SOP must include:
• A copy of the laser registration form
• Identification of hazards and corresponding control measures
• Detailed operating procedures (startup, shutdown, alignment, maintenance, safety precautions)
• Emergency procedures in case of an accident
• Copies of the SOP must be distributed to all laser operators and EHRS.
• Compile and submit a list of personnel and students with potential exposure to energized lasers. Ensure that all individuals
• Receive initial and annual refresher laser safety training from EHRS
• Are trained on the specific SOPs relevant to the lasers they will use
• Stay informed about laser safety training requirements, associated hazards, equipment configurations, and control measures for all lasers under their supervision.
• Conduct a formal safety review and perform hazard analyses, including:
• Establishing the Nominal Hazard Zone (NHZ)
• Implementing necessary corrective actions
• Classify or verify the classification of all lasers or laser systems under their responsibility.
• Control access and modifications to lasers under their supervision:
• Ensure lasers are not operated or modified without their direct approval
• Notify EHRS of any modifications
• Ensure all applicable personnel are enrolled in the medical surveillance program.
• Report all known or suspected laser-related incidents or accidents to EHRS.
• Provide and enforce the use of required protective equipment, including laser safety eyewear, clothing, barriers, screens, and interlocks.
• Ensure compliance with ANSI standards for signage and labeling, and that all designated laser areas are appropriately posted.
• Suspend, restrict, or terminate laser operations if a user is operating the laser unsafely or contrary to the SOP.

• Inform and protect spectators from potential laser hazards during operations.

The American National Standard for Safe Use of Lasers ANSI Z136.1- 2022 is available and can be purchased easily. EHRS has a copy of the standard that can be used as a reference.   

Laser Operator

Laser operators working with or near Class 3B and Class 4 lasers must:

• Complete laser safety training, including:
• Initial training prior to operating lasers
• Annual refresher training provided by EHRS
• Understand the specific hazards associated with the lasers they operate or are exposed to.
• Follow all applicable Standard Operating Procedures (SOPs) and comply with requirements set by the Laser Safety Committee, EHRS, and the supervising Clinician/PI.
• Operate Class 3B and Class 4 lasers only with explicit authorization from the Clinician/PI.
• Refrain from modifying any laser device without prior written approval from the Clinician/PI.
• Immediately report any known or suspected accidents or incidents involving lasers to both the Clinician/PI and EHRS.
• Register for and participate in the medical surveillance program, as required.
• Report unsafe conditions or practices to the Clinician/PI and EHRS without delay.

LASER CLASSIFICATION

Lasers and laser systems are classified based on their potential to cause biological harm. Higher classes indicate greater hazard potential—e.g., a Class 4 laser presents significantly more risk than a Class 3R laser—and therefore require stricter safety controls.

Commercial lasers are typically classified and labeled by the manufacturer. However, if a commercial laser is modified or a new laser is constructed at Temple University, it is the Clinician/Principal Investigator’s (PI) responsibility to classify and label the laser according to the ANSI Z136.1-2022 standard.

Class 1 Laser:

• Not capable of emitting hazardous levels of laser radiation under any operating or viewing condition.
• Exempt from most control measures and surveillance.
• Commonly found in consumer and office equipment (e.g., laser printers), where the embedded laser is often a Class 2 laser.

Note: If a higher-powered laser is embedded in a Class 1 system, and the housing is removed, access to the embedded laser negates the Class 1 safety status.

Class 1M Laser:

• Safe under normal operation but may be hazardous if viewed through optical instruments (e.g., magnifiers or telescopes).
• Exempt from control measures except those needed to prevent optically aided viewing.

Class 2 Laser (Low Power):

• Emits visible radiation (400–700 nm).
• Generally safe due to the human aversion response (blinking or turning away) to bright light within 0.25 seconds.
• Class 2A lasers are not meant for direct viewing but are safe if viewed for up to 1000 seconds.

Class 2M Laser:

• Also emits visible radiation.
• Safe due to the aversion response unless viewed with optical aids, in which case it may be hazardous.

Class 3R Laser (Medium Power):

• May pose an eye hazard under direct or specular reflection viewing if the eye is properly focused and steady.
• The risk of injury is low, and it does not pose a fire or diffuse reflection hazard.
• Previously classified as Class 3A (now reclassified as Class 3R). If beam diameter exceeds 7 mm, it may fall into Class 1M or 2M upon reassessment.

Class 3B Laser (Medium Power):

• Capable of causing eye injury from short-term intrabeam exposure (< 0.25s) or viewing of specular reflections.
• Not typically hazardous to skin and not a diffuse reflection hazard.
• Control measures focus on eye protection and exposure prevention to both direct and reflected beams.

Class 4 Laser (High Power):

• Highly hazardous to both eyes and skin.
• It can cause severe eye injury, serious skin burns, and present a fire hazard.
• Requires the strictest control measures, including restricted access, protective equipment, and beam enclosures when feasible.

Embedded Lasers

Lasers are frequently embedded within devices that, when used as intended, fall under a lower hazard classification (e.g., Class 1). However:

• If the housing is opened (e.g., for servicing or alignment), and the internal laser becomes accessible, the classification of the embedded laser determines the required controls.
• A temporary controlled area must be established when accessing embedded lasers, and controls must align with the classification of the exposed laser.
• System classification confirmation is the responsibility of EHRS, and all such systems must be registered.
• In some cases (e.g., enclosed commercial systems like laser scanning confocal microscopes), an abbreviated SOP may be required.

Table 1: Requirements based on Laser Classification

Note: During maintenance and services, the classifications associated with the maximum level of accessible laser radiation shall be used to determine the applicable control measures.

1. Not required except for conditions of intentional intrabeam exposure applications.
2. Certain uses of Class 1M or 2M lasers or laser systems that exceed Class 1 or Class 2 because they do not satisfy measurement Condition 1 may require hazard evaluation and/ or manufacturer’s information.   

LASER HAZARDS

Exposure to the Laser Beam

Exposure to a laser beam can occur in one of three primary ways:

• Intrabeam Exposure – Occurs when the eye or skin is directly exposed to the primary laser beam. This type of exposure presents the highest risk of injury, especially with Class 3B and Class 4 lasers.
• Specular Reflection – Happens when the laser beam is reflected off a smooth, mirror-like surface. The reflected beam retains much of its original power and can pose the same hazards as direct intrabeam exposure.
• Diffuse Reflection – Caused by the laser beam striking a rough or uneven surface, scattering the light in multiple directions. While typically less intense than specular reflections, diffuse reflections from high-powered lasers (e.g., Class 4) can still pose significant hazards, particularly to the eyes.

Non-Beam Hazards

• ¹Electrical Hazards — Lasers and laser systems can present several electrical hazards, especially due to their use of high-voltage power supplies and sensitive components. The primary risks include:
• Electrical Shock: May occur from contact with exposed power supply conductors, device control lines, or utility power components operating at 50 volts or more. The risk is heightened in the presence of water sources, which can increase conductivity and the likelihood of shock.
• Resistive Heating: Occurs when electrical current flows through a conductor with significant resistance. This can lead to excessive heat buildup, which may damage or corrode system components and create secondary fire or equipment failure hazards.
• Electric Spark Ignition of Flammable Materials: Equipment malfunctions may cause electrical arcing or sparks, which can ignite flammable vapors or materials in the vicinity. This risk is especially significant in environments with volatile solvents or gases.

• ¹Laser-Generated Air Contaminants (LGAC) — Air contaminants may be produced when certain Class 3B and 4 laser beams interact with materials.  LGAC can include metallic fumes and dust, metal oxide particulates, chemical vapors, gaseous by-products, and biological aerosols from human or animal tissue. Examples of compounds released from various materials include:

• Polycyclic aromatic hydrocarbons (PAHs) from thermal degradation of poly (methyl methacrylate)-type polymers
• Hydrogen cyanide and benzene from cutting of aromatic polyamide fibers
• Fused silica particles from laser processing of quartz
• Mutagenic compounds produced during laser surgery
• Heavy metals released during laser etching of metallic surfaces
• Benzene from cutting polyvinyl chloride (PVC)
• Cyanide, formaldehyde, and fiber particulates (synthetic and natural) from assorted laser-based processes

• ¹Collateral and Plasma Radiation — Collateral radiation refers to non-laser radiation that may be emitted by components of a laser system other than the laser itself. These sources can include:
• Power Supplies
• Discharge lamps
• Plasma tubes

This type of radiation may span multiple regions of the electromagnetic spectrum, including:

• X-rays
• Ultraviolet (UV) radiation
• Visible light
• Infrared (IR) radiation
• Microwave radiation
• Radiofrequency (RF) radiation

Exposure to collateral radiation can pose additional biological and electrical hazards, and appropriate shielding, PPE, and engineering controls should be implemented to minimize risk.

• ¹Fire Hazards Class 4 laser systems pose a significant fire hazard due to their high-power output. Fire risks can arise particularly when laser beams—direct, reflected, or scattered—interact with flammable materials.

• Beam Enclosures: Enclosures around Class 4 laser beams can become a fire hazard if they are made of materials that may be exposed to irradiances exceeding 10 W/cm². Materials not rated for high irradiance may ignite or degrade rapidly.

• Laser Barriers: Users of commercially available laser barriers should consult the manufacturer's fire safety specifications. Many of these barriers cannot withstand high irradiance levels for more than a few seconds without suffering damage or ignition.
• Combustible Materials: Operators should be aware that unprotected wire insulation, plastic tubing, and similar materials can ignite when exposed to intense reflected or scattered laser beams, especially from lasers operating at invisible (infrared or ultraviolet) wavelengths.

• Explosion Hazards — Explosion hazards can arise during laser operations, particularly from the ignition of combustible dust that may accumulate in ventilation systems serving laser processing areas.
• Dust generated during laser cutting, engraving, or ablation—especially from organic materials, metals, or polymers—can settle in ductwork and filters.
• If not properly maintained or cleaned, these dust accumulations can be ignited by laser sparks, hot surfaces, or electrical components, leading to a potential explosion.

Preventive measures should include regular inspection and cleaning of ventilation systems, appropriate dust filtration, and the use of explosion-rated components where applicable.

• Mechanical Hazards Associated with Robotics — When lasers are integrated with robotic systems, mechanical hazards may arise that increase the overall risk to personnel. Key risks include:
• Damage to Protective Systems: Robots may unintentionally puncture protective housing or disrupt beam delivery systems, potentially misdirecting the laser beam toward operators or other unintended targets.
• Unintended Beam Exposure: Malfunctioning or mis-programmed robotic arms can alter the beam alignment, causing hazardous exposure to the laser beam.
• Pinch or Crush Injuries ("Pinch Effect"): Workers can become trapped or pinned between a moving robot and a fixed object, resulting in serious injury. This is especially concerning in confined or automated environments.

• Noise — Some laser systems—particularly pulsed excimer lasers and those used in industrial or high-energy environments—can produce noise levels high enough to pose a risk to hearing. In such cases, noise control measures may be required to protect personnel.
• High-intensity noise may result from rapid gas discharges, vacuum pump systems, or high-frequency pulse mechanisms associated with laser operation.
• If noise levels exceed safe exposure limits, engineering controls, administrative controls, or personal hearing protection must be implemented.

For more information, please refer to EHRS Handbook & Policies, Hearing Conservation Program.

https://campusoperations.temple.edu/ehrs/occupational-safety/occupational-safety-programs#

• ¹Compressed Gases — Various hazardous compressed gases—including chlorine, fluorine, hydrogen chloride, and hydrogen fluoride—are commonly used in laser applications. These gases can pose significant health and safety risks if not handled properly. All compressed gas cylinders must be securely fastened to prevent tipping and stored in accordance with regulatory requirements. Typical safety issues associated with compressed gas use include:

• Use of freestanding cylinders in areas where they are not isolated from personnel, increasing the risk of tipping or collision.
• Lack of a remote shutoff valve or inadequate purging procedures before disconnecting or reconnecting gas lines.
• Hazardous gas cylinders not stored in appropriately ventilated enclosures (e.g., exhausted gas cabinets or fume hoods).
• Improper storage of gas types, including failure to segregate:
• Toxics
• Corrosives
• Flammables
• Oxidizers
• Inert gases
• High-pressure gases
• Cryogenic materials

For detailed safety procedures, please refer to EHRS Handbook & Policies, compressed gas SOP.

https://campusoperations.temple.edu/sites/campusoperations/files/documents/EHRS/Chemical-Safety/CHG-Compressed-Gases.pdf

• ¹Laser Dyes — Laser dyes are complex fluorescent organic compounds that, when dissolved in specific solvents, form the lasing medium for dye lasers. Many of these compounds are known to be highly toxic, and some may be carcinogenic. Because dye solutions often require frequent handling and replacement, strict safety measures must be followed during preparation and use.

Safety Requirements:

• Safety Data Sheets (SDS) for all dye compounds must be:
• Readily available in the work area
• Reviewed by all personnel who handle or may be exposed to the dyes
• Dye solution preparation must be conducted in a chemical fume hood to prevent inhalation of vapors and minimize exposure to potentially hazardous substances.
• Personal Protective Equipment (PPE) must be always worn when handling laser dyes, including:
• Lab coats
• Appropriate chemical-resistant gloves
• Eye protection (e.g., safety goggles or face shields)

• Assist Gases — commonly used in laser cutting, welding, and ablation—play a critical role in enhancing laser-material interactions (e.g., improving cut quality or cooling the work area). However, they can also contribute to the generation of Laser-Generated Air Contaminants (LGAC) and influence the spectral distribution of plasma radiation during laser operations. These gases, depending on the material being processed and laser parameters, may participate in reactions that:
  • Produce hazardous byproducts (e.g., ozone, nitrogen oxides, volatile organics)
  • Alter the emission characteristics of plasma plumes, potentially increasing exposure to ultraviolet or visible radiation
  • Increase respiratory and chemical exposure risks, particularly in enclosed or poorly ventilated spaces

Proper ventilation, gas-specific controls, and air monitoring may be necessary when using assist gases in laser applications.

• Biological Agents — Laser operations involving biological materials can pose significant health risks due to the generation of both Laser-Generated Air Contaminants (LGAC) and infectious aerosols.
  • LGAC: High-power laser beams interacting with biological tissue (e.g., during laser surgery or dissection) can produce airborne contaminants such as:
    • Cellular debris
    • Toxic gases
    • Particulates
  • Infectious Materials: Certain bacteria, viruses, and other pathogens may survive laser irradiation and become airborne in the form of bioaerosols. These can pose infection risks to personnel if inhaled or contacted through mucous membranes or open wounds.

Precautionary Measures:

• Use local exhaust ventilation (LEV) or smoke evacuators during biological laser procedures.
• Employ biosafety cabinets when working with known infectious agents.
• Ensure all personnel wear appropriate personal protective equipment (PPE), including respiratory protection when needed.
• Follow institutional biosafety protocols in conjunction with laser safety practices.

• Ergonomics — Poor ergonomic conditions in laser work environments can contribute to both short-term discomfort and long-term injury risks, as well as compromise operational safety. Hazards may result from a combination of physical layout issues, human-machine interactions, and visual strain.

Common Ergonomic Risk Factors:

• Inadequate workstation layout or limited workspace, restricting movement and increasing strain
• Inefficient work patterns and poor worker-machine interface design
• Improper manual handling techniques, leading to musculoskeletal injuries
• Insufficient or harsh area illumination, which can reduce visibility or increase fatigue
• Ergo-ophthalmological issues, such as:
  • Glare from reflective surfaces or screens
  • Startle reactions due to unexpected light exposure
  • Afterimages following brief, intense light exposure
  • Temporary flash blindness, which can increase the risk of accidents

Mitigation Measures:

• Conduct ergonomic assessments of laser workstations
• Ensure adequate task lighting and reduce glare
• Train staff in safe manual handling techniques
• Incorporate adjustable furniture or equipment to accommodate various users
• Use visual warning systems to reduce startle and flash-related incidents

• Laser and Laser Waste Disposal

Laser Disposal — Lasers that are no longer in use must be disposed of responsibly to ensure safety and regulatory compliance. There are three primary methods for laser disposal:

1. Donation or Transfer

Lasers may be donated to organizations such as schools, industrial facilities, or hospitals, provided the following conditions are met:

• The equipment complies with all applicable safety standards, including the Federal Laser Product Performance Standard (FLPPS).
• Comprehensive safety instructions for operation and maintenance are included.
• The recipient organization ensures that only trained personnel operate or service the laser.

1. Deactivation and Disposal

The laser may be rendered inoperable by removing all means of electrical activation (e.g., power supplies, control circuits). Once deactivated, it can be disposed of according to institutional procedures.

1. Destruction

The laser can be physically destroyed to eliminate any possibility of reuse or activation.

Note: EHRS must be notified and consulted before any laser system is disposed of by any method.

• Laser Waste Disposal — All waste materials contaminated by laser operations must be managed in accordance with federal, state, and local regulations. This includes:
  • Flue and smoke filters
  • Organic dyes and dye-contaminated materials
  • Solvent solutions and containers

Proper handling, labeling, and disposal procedures must be followed to minimize environmental and health risks. For detailed guidance, please refer to EHRS Handbook & Policies, Waste management.

https://campusoperations.temple.edu/ehrs/chemical-safety/chemical-safety-programs/chemical-waste-management-program

• Chillers — Laser systems can generate significant heat, often producing 2 to 1000 watts of thermal energy for every watt of optical power output. To manage this heat and maintain optimal laser performance, chillers are commonly used to remove excess thermal energy at controlled temperatures.

Key Considerations:

• Chillers are critical components in preventing laser system overheating, which could lead to equipment damage, system failure, or safety hazards.
• Chiller malfunction can result in excessive heat buildup, potentially exposing personnel to burn risks, increasing the chance of fire, or disrupting laser output stability.

Safety Measures:

• Perform regular maintenance and inspections of chiller units.
• Monitor coolant levels and flow rates and ensure proper temperature setpoints are maintained.
• Install thermal shutoff interlocks to disable laser operation in the event of cooling failure.
• Clearly label chiller systems and provide emergency shutdown procedures to all laser operators.

LASER SAFETY CALCULATIONS

¹Maximum Permissible Exposure (MPE) – The Maximum Permissible Exposure (MPE) is defined as the highest level of laser radiation to which a person may be exposed without experiencing hazardous effects or adverse biological changes to the eyes or skin.

MPE Determination Requires the Following Parameters:

• Temporal Output Category:
  • Continuous Wave (CW)
  • Single-Pulsed
  • Repetitively Pulsed
• Laser Wavelength
• Anticipated Exposure Duration
• Irradiance (for CW lasers) or Radiant Exposure (for pulsed lasers)

Reference Tables:

• ANSI Z136.1-2022 Table 5: MPE values for ocular exposure
• ANSI Z136.1-2022 Table 7: MPE values for skin exposure
• ANSI Z136.1-2022 Table 6: Correction factors applicable to Tables 5 and 7, based on specific exposure conditions

Accurate MPE assessment is essential for hazard evaluation and the selection of appropriate engineering controls, personal protective equipment (PPE), and safe operating procedures.

¹Optical Density (OD) Optical Density (OD) is a measure of the attenuation capability of a transmitting medium, such as laser safety eyewear or a protective filter. It is used to specify how much laser radiation is reduced when passing through the material.

OD is especially critical in the selection of appropriate laser eye protection. The required OD depends on the power or energy of the laser and the Maximum Permissible Exposure (MPE) at the specific wavelength and exposure conditions.

Important Note: If the required OD exceeds a value of 6, engineering controls (such as beam enclosures or interlocks) should be implemented to prevent exposure, rather than relying solely on eyewear.

OD Calculation Formula:

OD = log₁₀ [H / MPE] or

OD = log₁₀ [E / MPE]

Where:

• H = Radiant Exposure (J/cm²) for pulsed lasers
• E = Irradiance (W/cm²) for continuous wave (CW) lasers
• MPE = Maximum Permissible Exposure (based on ANSI Z136.1-2022)

¹Nominal Hazard Zone (NHZ) – The Nominal Hazard Zone (NHZ) is defined as the space within which the level of direct, reflected, or scattered laser radiation exceeds the applicable Maximum Permissible Exposure (MPE).

• Outside the NHZ, laser radiation levels are below the MPE, and therefore no control measures are required.
• The NHZ is a critical factor in laser safety planning, particularly for Class 3B and Class 4 lasers, where exposure risk is significant.

NHZ for Ocular Exposures (RNOHD)

Ocular exposure is the primary concern in laser safety due to the eye's sensitivity to laser radiation. The Nominal Ocular Hazard Distance (RNOHD) defines the distance from the laser source within which the eye could be exposed to radiation levels above the MPE.

RNOHD Formula:

R_NOHD = (1/f) [(4 F/p MPE)^1/2-a]

Where:

• 𝜙 = Beam divergence, in radians
• Φ = Total radiant power of a continuous wave (CW) laser, or average radiant power of a repetitively pulsed laser (in watts)
• MPE = Maximum Permissible Exposure (W/cm²)
• a = Diameter of the emergent beam, in centimeters

This formula assumes Gaussian beam distribution and free-space propagation. Actual hazard distances may vary with reflective surfaces, beam quality, and environmental conditions.

CONTROL MEASURES

Control measures are outlined in Table 3: Control Measures for the Four Laser Classes.  These measures are designed to mitigate hazards associated with laser operation and include both engineering controls and administrative/procedural controls.

Types of Control Measures:

• Engineering Controls
  • Protective housing
  • Interlocks
  • Beam enclosures
  • Signage and labeling
  • Beam stops and shutters
• Administrative and Procedural Controls
  • Standard Operating Procedures (SOPs)
  • Laser safety education and training
  • Designation of Laser Safety Officers (LSOs)
  • Access control and area restrictions
• Use of appropriate personal protective equipment (PPE)

For assistance interpreting or implementing the measures listed in Table 3, please contact Environmental Health and Radiation Safety (EHRS)

Protective Eyewear: Protective eyewear is mandatory for all personnel operating or working near Class 3B and Class 4 lasers. Eyewear must meet ANSI Z136.1 standards and be selected based on the specific laser’s characteristics.

Eyewear Selection Process:

1. Identify the laser wavelength (in nanometers).

2. Determine the maximum anticipated viewing duration:

• ²Visible lasers (400–700 nm): 0.25 seconds (accidental exposure)
• ²Infrared lasers (700 nm – 1 mm): 10 seconds (accidental exposure)
• ²Ultraviolet lasers (100–400 nm): Use actual laser-on time, up to 8 hour

​​​​​​​3. Determine the laser’s output (irradiance or radiant exposure).

4. Calculate the required Optical Density (OD):

• EHRS can assist in performing OD calculations.

​​​​​​​5. Select appropriate eyewear based on OD and wavelength requirements.

6. Inspect eyewear regularly for:

• Cracks or pinholes
• Frame and filter integrity
• Secure and undamaged straps

Important Note: Laser protective eyewear is not intended for direct viewing of the laser beam (intrabeam or specular reflection).

LASER ALIGNMENT SAFETY PRACTICES

Proper laser alignment is critical for safety and equipment longevity. The following practices shall be adhered to:

• Use the lowest possible laser power during alignment.
• Always wear protective eyewear rated for the laser wavelength.
• Use beam blocks and IR/UV viewers as necessary.
• Never place reflective objects in or near the beam path during alignment.
• Avoid solo work when aligning Class 3B or Class 4 lasers.

MEDICAL SURVEILLANCE

Per ANSI Z136.1-2022, Appendix E, medical surveillance is recommended for individuals routinely working with Class 3B and Class 4 laser systems, particularly those with potential for accidental or chronic exposure to laser radiation.

Baseline Eye Examination

• Clinicians/Principal Investigators (PIs) should ensure that laser personnel assigned to operate or align Class 3B or Class 4 lasers receive a baseline eye examination.
• The exam should be conducted by a licensed ophthalmologist or other qualified eye care professional and may include:
  • Visual acuity
  • Color vision
  • Amsler grid assessment
  • Retinal evaluation (especially for exposure to visible or near-infrared wavelengths)
• The PI is responsible for the cost of the examination and should coordinate scheduling through the Department of Ophthalmology or designated occupational health provider.
• This exam should be conducted prior to the initiation of laser work.

Post-Exposure Examination

• If a suspected or confirmed laser-related ocular injury occurs, the affected individual must undergo a prompt eye examination.
• The exam should document the extent of injury and guide any necessary medical treatment or follow-up.

Exit Eye Examination (Recommended)

• It is recommended by EHRS that laser personnel working with Class 3B, or Class 4 lasers receive an exit eye examination at the end of their assignment or upon termination.
• This provides documentation of ocular health at the conclusion of laser work.

Recordkeeping and Confidentiality

• Medical records related to laser surveillance must be maintained in compliance with institutional policy and applicable privacy laws.
• EHRS may request confirmation of completed exams but will not retain or review detailed medical records.

ADULT VISITORS AND CHILDREN

Children

• Children are strictly prohibited from entering laser research laboratories unless prior written approval has been obtained from Environmental Health and Radiation Safety (EHRS).
• This policy is in place to ensure their safety and comply with regulatory and institutional risk management standards.

Adult Visitors

• Adult visitors are strongly discouraged from entering laser laboratories while Class 3B or Class 4 lasers are in operation.
• If a visit during active laser use is necessary, the Clinician/Principal Investigator (PI) is fully responsible for ensuring the visitor’s safety.

Minimum Required Precautions:

• Assign a trained escort to accompany the visitor at all times.
• Provide basic laser safety information prior to entry, including potential hazards and restricted behaviors.
• Supply appropriate laser protective eyewear if the visitor will be exposed to laser radiation above the Maximum Permissible Exposure (MPE) level.

Note: Visitors should never be left unattended in any area where active laser use is occurring.

SUPPORTING REFERENCES AND STANDARDS

1. American National Standards Institute (ANSI). American National Standard for the Safe Use of Lasers, ANSI Z136.1-2022.  New York: ANSI, 2022.
2. Code of Federal regulations, Title 21, part 1040.  Performance Standards for Light-Emitting Products.  Washington, DC: Office of the Federal register.
3. Laser Institute of America. Laser Safety: Hazards, Inspections and Controls. Orlando: Laser Institute of America, 1996.
4. Sliney, David & Myron Wolbarsht.  Safety With Lasers and Other Optical Sources.  New York: Plenum Press, 1980.

BIOLOGICAL EFFECTS

Table 2: Summary of Laser Biological Effects

Table 3: Summary of Bioeffects of Commonly Used Lasers

X = Hazard is present

Table 4: Control Measures for the Four Laser Classes

LEGEND             

X =      Shall

·  =      Should,

¾  =    No requirement

Ñ=       Shall if enclosed Class 3B or Class 4

MPE = Shall if MPE is exceeded

NHZ = NHZ analysis required

* =       May apply with use of optical aid

Table 3 (con’t): Control Measures for the Four Laser Classes

LEGEND        

X =    Shall

·  =    Should,

¾  =  No requirement

Ñ=  Shall if enclosed Class 3B or Class 4

MPE = shall if MPE is exceeded

NHZ = NHZ analysis required

* =       May apply with use of optical aid

​​​​​​​revised 6/2025