Which of the following is a common type of personal protective equipment (PPE)?

A hard hat is a common type of personal protective equipment (PPE) because it is specifically designed to protect the head from injury due to falling objects, impact, or electrical hazards. In industrial, construction, and certain workplace environments, head protection is crucial to ensuring the safety and well-being of workers. Hard hats feature a rigid outer shell and inner foam padding that can effectively absorb impact and provide a barrier against potential hazards.

In contrast, office chairs, desk lamps, and computer keyboards do not serve a protective role in hazardous environments. While they are essential for comfort and functionality, especially in office settings, they do not contribute to personal safety in the same manner that hard hats do. Therefore, hard hats are recognized as a vital component of PPE, while the other options do not fit this classification.