Final answer:
A common cause of extra or frequent rust in air tools is exposure to moisture and oxygen, especially in humid environments. Scratches or defects in the protective coating can accelerate the rusting process.
Step-by-step explanation:
A common cause of extra or frequent rust in air tools is exposure to moisture and oxygen. When iron, which is the primary component of air tools, reacts with atmospheric oxygen in the presence of moisture, it undergoes oxidation and forms iron oxide, commonly known as rust. This process is accelerated if there are any scratches or defects in the protective coating of the tools, as it allows for easier access of oxygen and moisture to the iron surface.
Oxygen and water are required for rust to form, so if the air tools are continuously exposed to a humid environment, such as in coastal areas or in workshops with high humidity levels, they are more likely to experience extra or frequent rust. To prevent rust, it is important to keep air tools dry and free from moisture, and to regularly inspect and maintain the protective coating.