Which of the following cannot be present in an area where empty drums that have held flammable products are being welded or cut?

Welding or cutting operations near empty drums that previously contained flammable products pose significant risks due to the potential for explosive vapors to be present. In such hazardous environments, safety protocols are crucial in minimizing the chance of ignition.

Using oxygen for cooling in this context is particularly dangerous because increasing the concentration of oxygen can facilitate combustion. Welding and cutting can generate sparks and high heat, increasing the potential for igniting any residual flammable vapors inside the drums. Therefore, having additional oxygen in the vicinity, especially in a highly flammable environment, needs to be avoided.

In contrast, protective gear is essential to ensure the safety of workers; waste disposal containers can assist in managing debris safely; and dust blowers can help in maintaining a clear workspace, though they must be used carefully to avoid the dispersion of flammable residues. Hence, the combination of welding or cutting operations and the use of additional oxygen creates a significantly unsafe scenario, validating that oxygen is not safe to have present in these conditions.