Electromagnetic energy given off by an arc or flame can injure workers’ eyes and is commonly referred to as radiant energy or light radiation. For protection from radiant energy, workers must use personal protective equipment, such as safety glasses, goggles, welding helmets, or welding face shields.

This equipment must have filter lenses with a shade number that provides the appropriate level of protection.

A shade number indicates the intensity of light radiation that is allowed to pass through a filter lens to one’s eyes. The higher the shade number, the darker the filter and the less light radiation that will pass through the lens.

This requirement applies to the employees performing the work and to personnel observing the operation; for example, a fire watch or an assistant.

When a worker wears eyewear equipped with filter lenses under a welding helmet, the shade number of the lens in the helmet may be reduced. In addition, all protective eye and face devices must comply with ANSI Z87.1,Practice for Occupational and Educational Eye and Face Protection (see 29 CFR 1915.153(b)) for the selection, use and maintenance of these protective devices.

When there is a potential for objects to fly in workers’ eyes and face, the protective device(s) selected must provide side protection. Side protection reduces the risks of hazards such as slag chips, grinding fragments and grinding bristles contacting a worker’s eyes and face. Where such hazards exist, workers using a welding helmet with filter lenses would also need to wear glasses with side shields or goggles.

Source: OSHA