CO₂ Laser Safety: Eye, Skin, Fire, and Non-Beam Hazards

CO₂ lasers can present serious eye, skin, fire, and non-beam hazards. The appropriate controls depend on the specific laser system, application, and reasonably foreseeable worst-case exposure conditions.

CO₂ lasers are widely used for cutting, engraving, marking, welding, medical procedures, and industrial material processing.

Many high-powered CO₂ lasers are Class 4 laser systems or contain lasers capable of producing Class 4 levels of radiation, meaning appropriate engineering controls, administrative controls, and personal protective equipment may be required depending on how the system is configured and used.

Laser radiation is only one part of the potential hazard.

A CO₂ laser application can involve:

Understanding all of these hazards is an important part of establishing a safe laser work area. The difference between a hazard evaluation and a lasers class here or see this video:

Many CO₂ lasers operate at approximately:

10,600 nm (10.6 µm)

This is infrared radiation that is invisible to the human eye.

However, not every CO₂ laser operates at exactly 10,600 nm. CO₂ lasers can operate on other emission lines, including wavelengths around 9.3 µm and 9.6 µm.

Always verify the actual operating wavelength of the laser.

Any visible light produced during cutting, engraving, welding, or another process should not automatically be interpreted as the CO₂ laser beam itself. Some systems also use a separate visible aiming beam to indicate the intended location of the invisible operating beam. For more information, see the difference between an aiming beam and an operating beam. Here is a video:

For more information, see What Wavelength Is a CO₂ Laser? Understanding 10,600 nm (10.6 µm).

CO₂ laser radiation can cause serious eye injury.

The location of potential injury differs from that associated with visible and near-infrared lasers.

Visible and near-infrared wavelengths can pass through the front structures of the eye and be focused onto the retina. CO₂ wavelengths around 10.6 µm are strongly absorbed by water and are therefore absorbed primarily by the front structures of the eye, particularly the cornea.

This means that although CO₂ radiation is not generally considered a retinal hazard in the same way as visible or near-infrared laser radiation, it can still cause severe ocular injury.

The fact that the beam is invisible can make the hazard particularly difficult to recognize without appropriate controls.

A direct beam is not the only potential source of laser exposure.

CO₂ laser radiation can reflect from materials in the work area. Depending on the surface and wavelength, these reflections may be specular, diffuse, or somewhere between the two.

A specular reflection can redirect a relatively concentrated amount of laser energy in another direction.

A diffuse reflection spreads energy over a larger range of directions, generally reducing irradiance as the energy spreads. However:

Diffuse does not automatically mean safe.

High-powered Class 4 lasers can produce hazardous reflected or scattered radiation.

Material behavior is also wavelength-dependent. A surface's visible appearance does not necessarily tell you how it will reflect or absorb radiation at approximately 10.6 µm.

For more information, see Are CO₂ Laser Reflections Dangerous?

CO₂ lasers can also cause thermal injury to the skin.

At CO₂ wavelengths, laser radiation is strongly absorbed near the surface of water-containing tissue. Sufficient exposure can therefore result in:

The severity depends on factors such as irradiance, exposure duration, beam size, wavelength, and the conditions of exposure.

Protective clothing, gloves, barriers, enclosures, and other controls may be appropriate depending on the application and hazard evaluation.

High-powered CO₂ lasers are frequently used precisely because they can heat, melt, vaporize, or cut materials.

That same capability can create a fire hazard.

Potential ignition sources can include:

Materials that are not intended to be processed can also become hazardous if they enter the beam path or are positioned too close to the laser process.

The work area should be evaluated for combustible materials and other potential fire hazards, and appropriate fire prevention and response procedures should be established.

Material processing can produce laser-generated airborne contaminants (LGACs).

Depending on the material being processed, these can include:

The composition and severity of these emissions depend heavily on the material.

This is why knowing what material is being processed is an important part of laser safety.

Appropriate ventilation or local exhaust may be required to capture contaminants near the source and prevent them from accumulating in the work area.

Materials should not be laser processed simply because the laser is physically capable of cutting or engraving them. The potential decomposition products should also be considered.

CO₂ laser systems can contain high-voltage electrical components.

Depending on the system, these can include:

Electrical energy may remain stored even after equipment has been turned off.

Service and maintenance should therefore be performed according to the manufacturer's procedures by appropriately qualified personnel.

Laser safety eyewear does not protect against electrical hazards.

Some CO₂ laser systems and processes use compressed gases.

These may be associated with:

Compressed-gas cylinders and systems introduce hazards separate from the laser beam itself and should be stored, secured, handled, and maintained appropriately.

The particular gas can introduce additional hazards that should also be evaluated.

Industrial CO₂ laser systems may incorporate moving machinery such as:

These systems can create pinch, crush, entanglement, and other mechanical hazards.

The laser may therefore be only one component of the overall machine-safety evaluation.

Not every CO₂ laser application exposes the operator to hazardous laser radiation during normal use.

Some CO₂ laser cutters contain high-powered laser sources inside a protective enclosure and are classified as Class 1 laser products because laser radiation above the applicable Class 1 accessible emission limits is not accessible under the conditions applicable to that classification.

For normal operation of such a system, laser-specific PPE such as laser safety eyewear may not necessarily be required.

However, service, maintenance, alignment, modification, removal of protective housings, or defeating interlocks can create very different exposure conditions.

Those tasks should be evaluated separately.

For more information, see Do I Need Laser Safety Glasses for an Enclosed CO₂ Laser Cutter?

Where hazardous CO₂ laser radiation could be accessible, engineering controls are generally an important part of the safety system.

Depending on the application, these may include:

Personal protective equipment provides an additional layer of protection when required, but PPE should not be treated as a substitute for appropriate engineering controls.

When laser safety eyewear is required, it must provide protection at the actual operating wavelength of the laser and sufficient optical density for the reasonably foreseeable worst-case exposure conditions.

Do not select eyewear based solely on:

“This is a CO₂ laser.”

And do not select it solely from:

“This laser is X watts.”

The wavelength and required OD must both be considered.

For more information, see What Safety Glasses Do I Need for a CO₂ Laser?

When an open CO₂ laser process requires containment, barriers or curtains should also be appropriate for the actual wavelength and potential exposure at the containment boundary.

The laser's total wattage does not by itself tell you the irradiance that will reach the barrier.

Barrier selection can depend on beam characteristics, distance, geometry, reflections, exposure duration, and reasonably foreseeable worst-case beam paths.

For more information, see What Type of Barrier or Curtain Do I Need for a CO₂ Laser?

One of the most important principles in CO₂ laser safety is that a hazard evaluation should consider the entire application, not simply the laser's classification or output power.

Depending on the system, the most significant practical hazard may be:

Laser classification and hazard evaluation therefore answer different questions.

Classification describes the laser product's accessible emission relative to defined limits. A hazard evaluation considers the actual application and determines the controls needed for the hazards present.

CO₂ laser safety involves more than protecting against the primary laser beam.

A complete evaluation should consider:

Eye + Skin + Reflections + Fire + Fumes + Electrical + Gas + Mechanical Hazards

Many CO₂ lasers operate near 10,600 nm, but the actual wavelength should always be verified.

For open or service conditions where hazardous laser radiation is accessible, appropriate engineering controls, administrative controls, and PPE should be established based on the reasonably foreseeable worst-case exposure conditions.

For enclosed systems, the system's classification and the specific operating or service condition should be considered.