Answer:
By using insulating material.
Explanation:
By making the material cover with insulator in that way the we can protect the workers from the dangers of high heat because the insulator are the poor conductor of heat so the heat from the surrounding environment did not enter inside the metal. There are certain materials which remain cool if they receive heat from the surrounding environment so by using these types of materials can be useful on the cover of caisson to reduce heat in the inner side and protect the workers from the dangers of high heat.
