OSHA 1910.136(a) states that:
General requirements. The employer shall ensure that each
affected employee uses protective footwear when working in
areas where there is a danger of foot injuries due to falling
or rolling objects, or objects piercing the sole, and where
such employee’s feet are exposed to electrical hazards.
And from 1910 Subpart I App B:
Some [...]

Just about any welding, cutting, or brazing process produces measurable and damaging amounts of light. It occurs in the infrared, visible, and ultraviolet light spectrum, but the most damaging is the ultraviolet portion. This is due to the fact that the ultraviolet light spectrum has a shorter wavelength, and shorter wavelengths [...]