In addition to engineering and administrative controls, personal protective equipment for skin and/or eyes is often necessary when working with Class 3B or Class 4 lasers.
Eye protection suitable to the laser must be provided and worn within the laser control area if there is a potential for exceeding the MPE limit if the beam is viewed. Protective eyewear may include goggles, face shields, spectacles or prescription eyewear using special filter materials or reflective coatings. Exceptions may be approved in the written SOPs if the eyewear produces a greater hazard than when the eye protection is not worn.
No single type of eyewear will provide protection against all wavelengths of laser radiation; therefore, eye protection should:
- Provide enough visibility to move about safely.
- Be able to withstand the maximum power of laser radiation likely to be encountered.
- Be able to absorb the specific wavelength of radiation that is being used.
- Be clearly labeled with wavelength they are designed for, the optical density at that wavelength, together with the maximum power rating.
- Be inspected periodically by the laser operator to ensure that pitting, cracking and other damage will not endanger the wearer.
Lasers that can be tuned through a range of wavelengths present special problems. Broad band laser goggles may provide the level of protection required but they must be chosen with great care. If there is any doubt regarding the suitability of a particular type of eye protection, contact the Laser Safety Officer at 5-8501 for guidance.
Skin injuries from lasers primarily fall into two categories: thermal injury (burns) from acute exposure to high power laser beams and photochemically induced injury from chronic exposure to scattered ultraviolet laser radiation.
Thermal injuries can result from direct contact with the beam or specular reflections. These injuries (although painful) are usually not serious and are normally easy to prevent through proper beam management and hazard awareness.
Photochemical injury may occur over time from ultraviolet exposure to the direct beam, specular reflections, or even diffuse reflections. The effect can be minor or severe sunburn, and prolonged exposure may promote the formation of skin cancer. Proper protective eyewear and clothing may be necessary to control UV skin and eye exposure.
Clothing such as gloves and covers for the forearms may be required to protect the skin if laser intensity and wavelength warrant such protection. This is most important if the laser is running in the ultra-violet. Very large peak powers with pulsed ultra-violet laser can be particularly dangerous. Contact the Laser Safety Officer at 5-8501 for specific information regarding protective clothing.
Other protective equipment includes window drapes designed to prevent the escape of the laser beam outside of the room that it is in. The type of drape used must be appropriate to the laser. Some laser beams such as that from a CO2 laser do not penetrate glass and therefore do not require the use of window drapes.
NOTE: By OSHA regulation all laser users required to wear personal protective equipment must undergo a hazard assessment for PPE use and must receive specific PPE training. Forms for completing each are included as Appendix 3 to this manual. Completion of these two items for each laser user is the responsibility of the Principal Investigator.