1. Why should safety eyewear protect against UV and IR rays ?

Various industrial processes emit IR rays i.e. over luminous transmittance. Also there is very strong UV rays spectrum below luminous transmittance in tropical countries like India. These radiations can cause cataract, retinal bum, painful eye condition, skin cancer around the eyelids etc. The lens of safety spectacles are made up of polycarbonate material which block the entry of UVs radiation into the eyes. Shaded PC lens protect against IR rays.