October 9, 2003
In the industrial environment, safety glasses are a necessity for jobs that put employees' eyes at risk of exposure to heat, impact, chemicals, or dust. But workers also need protection from nonimpact dangers, such as radiant energy, eye strain, and fatigue. So choosing the appropriate lens or filter plate for your workers' eye protection is just as important in preventing eye injury as is selecting the appropriate style of safety eyewear.
Radiant energy exposure, also called optical radiation, occurs with work applications that involve intense concentrations of ultraviolet (UV), infrared (IR), and intense visible light. Arc welding and cutting, as well as laser welding, cutting, and brazing, can expose workers to this type of radiation.1
Exposure to UV and IR rays can damage the eyes and the skin. Sometimes damage occurs without the worker realizing it, because UV and IR radiation cannot be seen. Exposure to UV light can lead to photokeratitis, a painful experience more commonly known as snow blindness or welder's flash. IR light is fundamentally less damaging, but workers in blast furnace environments should be protected against exposure, which has been associated with chronic damage to the human lens.
Workers are at risk of welder's flash injury even when they are not involved directly in the welding process. While pupillary reflex and shading of the eyes are natural reflexes to guard the eye from exposure, eye protection is still necessary to protect those who may accidentally be exposed to a welding arc.
While the type of protection you choose ultimately depends on your employees' work applications, the following is a general guide to the types of lenses and equipment available to protect welders from exposure to optical radiation.
Clear polycarbonate lenses meet the American National Standards Institute (ANSI) Z87.1-1989 standard for industrial impact resistance and work best for indoor applications for which protection from splashes, sparks, or flying particles is necessary. Many styles of clear safety glasses are on the market, offering everything from side shields to wraparound lenses to brow guards.
Choosing the right style comes down to the hazards of the working environment. For some applications, safety glasses with side shields are necessary to protect against flying particles. For other jobs, goggles might be more practical because they provide a seal around the eyes. Goggles, too, come in different styles for protection from splashes (goggles without vents or with indirect vents) and protection from particles (goggles that feature side vents for airflow).
Clear polycarbonate safety glasses, in addition to guarding against particles or splashes, also can block UV radiation up to 385 nanometers. According to Dr. Felix Barker, director of research at the Pennsylvania College of Optometry, this blocking ability makes clear safety glasses helpful for guarding nonwelders from indirect exposure to UV rays generated by welding. Side shields also are important if indirect exposure is a possibility.
"It doesn't take much exposure to be affected by UV rays. An unprotected worker could be standing off to the side while others are welding and a few hours later end up with painful eyes," Barker said.
The light given off during most welding processes is as bright as the sun, which makes retinal damage a real issue for welders, according to Barker. Welders are protected from this light by wearing a very dark filter that allows them to look safely at the welding arc, enabling them to produce a quality welded seam.
The type of welding application determines the correct shade for eye protection. The Occupational Safety and Health Administration (OSHA) regulation 1910.133 contains a guide for choosing the appropriate filter lenses, based on various operations (see Figure 1at the bottom of page). OSHA recommends that welders start with a shade that is too dark to see the weld zone, then go to a lighter shade that allows for a sufficient view of the weld zone without going below the minimum recommended protective shade.
Faceshields also are important because they can protect the welder from sparks, slag, and fumes.
Some faceshields come with removable filter plates that can be replaced with lighter or darker shades to suit the type of welding being done. The removable plates also are convenient when the plate becomes scratched or otherwise damaged.
It's important to remember that most faceshields do not meet the ANSI Z87.1-1989 standards for impact protection. If impact hazards are a concern, safety glasses also must be worn underneath the faceshield to guard against sparks that might find their way beneath the shield. Wearing safety glasses under the faceshield is always good practice, because welders frequently lift their shields, inadvertently exposing their eyes to the hazards produced by other welders.
Helmets with extended neckpieces are another option to protect the eyes and face from flying sparks.
Welding helmets with autodarkening lenses work well for those who perform a variety of welding operations that require different shades of protection. They allow welders to keep their helmets down at all times, preventing the neck strain that can come from trying to flip down a faceshield when striking the arc. Helmets also can reduce the need for wearing secondary safety lenses under the shield.
Although autodarkening lenses do not darken until an arc is struck, if the helmet is ANSI-compliant, it will already block out UV and IR rays whether the helmet is on or off. Helmets that take a millisecond or less to change shades are recommended.2
Autodarkening lenses can be battery-powered or solar-powered. Battery-powered helmets have very small computers attached to photosensors on the outside of the helmet that determine when the lens should darken. Solar-powered helmets, on the other hand, are fueled by light from the welding arc through a solar cell. The advantage to the solar cell is that the welder does not have to remember to turn the helmet off after use.
For less hazardous types of welding, such as torch brazing, light electric, and spot welding, goggles with a shade of 5.0 can be convenient. Safety glasses equipped with 1.7 to 3.0 lenses also can be useful in situations in which sparks and spatter are not a concern.
A variety of eye protection is available to keep your employees safe. Before choosing safety glasses, take the time first to assess the hazards that exist in your workplace. Gauging the dangers that exist will help guide you to the right choice for protective eyewear and allow your employees to keep their eyes on their work.
Julie Copeland is vice president of sales for Arbill Industries, which includes Arbill Industrial Laundry and Arbill Safety Products, 10450 Drummond Road, Philadelphia, PA 19154, 800-523-5367, fax 800-426-5808, firstname.lastname@example.org, www.arbill.com.
1. American Welding Society, "Safety and Health Fact Sheet No. 2" (Miami: AWS, 1998).
2. Jim Harris, "Commonly Asked Questions About Auto-Darkening Welding Helmets, Eye Protection," Auto Inc. Magazine, January 2002.