Which of the following is NOT a common hazardous metal during the welding process?

Sodium chloride is not typically associated with the welding process, making it the correct choice in this context. Welding generates fumes and particulate matter primarily from the materials being welded, as well as the coatings and fluxes used in the process. Zinc oxide, iron oxide, and cadmium are all metals or metal oxides that can be released during various types of welding.

Zinc oxide may result from welding galvanized steel, which is coated with a layer of zinc to prevent rust. Iron oxide can occur from the welding of ferrous metals, as the base metal itself generates fumes. Cadmium is another hazardous metal that can be present in certain alloys or coatings and poses serious health risks when inhaled during welding operations.

Given this context, sodium chloride, while hazardous in certain conditions, is not intrinsically linked to welding, which involves the melting and fusion of metals and their oxides rather than salts like sodium chloride.