Control Measures for Laser Classifications
ANSI Z136.1 requires specific control measures for each laser classification and the environment
in which they are used. The chart above lists some of the requirements that may need to be im-
plemented in a laboratory setting. The company Laser Safety Officer, or designee, should refer-
ence the applicable safety regulations for appropriate control measures to implement in the area
the instrument will be used.
Biological Effects of Laser Irradiation
Eye Injury
Because of the high degree of beam collimation, a laser serves as an almost ideal point source of
intense light. A laser beam of sufficient power can theoretically produce retinal intensities at magni-
tudes that are greater than conventional light sources, and even larger than those produced when
directly viewing the sun. Eye exposure to a direct beam can cause permanent eye damage includ-
ing blindness. Protective eyewear should always be worn when potential exposure to direct laser
beams exist.
• Due to the lens-like focusing effect of the human eye, it is 100,000 times more vulnerable
to injury than the skin. Laser safety eyewear should always be available for the wave-
lengths of lasers in use.
•
Eye protective equipment, however, should be considered the last line of defense against
laser beam exposure – engineering and administrative controls should be used first.
•
Remove all jewelry when working with an open beam to prevent reflection of the beam in
unsafe directions.
• When possible, use all protective housings, interlocks and shields.
• Laser Safety Eyewear should always be worn during laser repair,
• alignment, or installation, or at any time when any laser safety control is not in place.
Thermal Injury
The most common cause of laser-induced tissue damage is thermal in nature, where the tissue
proteins are denatured due to the temperature rise following absorption of laser energy. The ther-
mal damage process (resulting in burns) is generally associated with lasers operating at exposure
times greater than 10 microseconds and in the wavelength region from the near ultraviolet to the
far infrared. Tissue damage may also be caused by thermally induced acoustic waves following
exposures to sub-microsecond laser exposures.
Skin Injury
To the skin, UVA (315-400 nm) can cause hyperpigmentation and erythema (aka: sunburn). Expo-
sure in the UVB (280-315 nm) range is most injurious to skin. In addition to thermal injury caused
by ultraviolet energy, there is also possibility of radiation carcinogenesis from UVB. The shorter
wavelengths are absorbed in the outer dead layers of the epidermis (stratum corneum) and the
longer wavelengths have an initial pigment-darkening effect followed by erythema if there is expo-
sure to excessive levels.
The hazards associated with skin exposure are of less importance than eye hazards; however, with
the expanding use of higher-power laser systems, particularly ultraviolet lasers, the unprotected
skin of personnel may be exposed to extremely hazardous levels of the beam power if used in an
unenclosed system design.
Skin burns caused by lasers can happen quite fast and with great intensity. Protective clothing
should be worn when potential exposure to direct laser beams exist.
• UVC: 200-280 nm exposure may cause erythema (sunburn), skin cancer, and burns.
• UVB: 280-315 nm exposure may cause accelerated skin aging, increased skin pigmenta-
tion and burns.
• UVA: 315-400 nm exposure may cause pigment darkening and skin burns.
• Visible: 400-700 nm exposure may cause photosensitive reactions and skin burns.
• Infrared 700-100,000 nm exposure may cause skin burns.
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