Answer to Question #938 Submitted to "Ask the Experts"

Laser protective eyewear is required to be worn by all staff in an area where a class 3b or 4 laser is operating unless the beam is totally enclosed and inaccessible or an individual is outside the nominal hazard zone (NHZ; an NHZ delineates where the exposure is below permissible levels). The proper type of eyewear protection for a specific laser beam must be calculated using the laser output, wavelength, beam divergence, type of optics through which the beam is viewed, and distance of the person being exposed.

The American National Standards Institute has laser standards that show how these calculations are performed. The reports also contain the safety requirements required for different classifications of laser systems. ANSI Z136.1 is the general standard but there some that are specific to applications, e.g., ANSI Z136.3 is for health care uses. These standards have some excellent information not only regarding eyewear but also record keeping and training information, and some sample standard operating procedures.

Some states also have regulations or guidelines for safe use of lasers. A copy of the Suggested State Regulation can be obtained from the Conference of Radiation Control Program Directors. The nonionizing portion costs $25. There also are vendors/consultants who can assist in choosing the right eyewear (they do all the calculations for you!). I use Rockwell Laser Industries, but there are several and a search on the Web would generate a list for you.

Kelly Classic
Certified Medical Health Physicist