Final answer:
The person responsible for shielding a welding arc is the Welder. Welders wear protective gear such as gloves and helmets to protect themselves from thermal energy, sparks, and high-energy electromagnetic radiation.
Step-by-step explanation:
The person responsible for shielding a welding arc to protect the eyes and skin of all persons in the working area is the Welder.
Welders wear protective gear such as gloves and helmets to shield themselves from the electric arc that emits thermal energy, sparks, and high-energy electromagnetic radiation. The thermal energy can be felt on exposed skin and its light can be seen for kilometers, making it crucial for welders to protect themselves.