Which of the following is a common hazard in aircraft structures environments?

In aircraft structures environments, exposure to compressed air is indeed a common hazard. This environment often involves the use of pneumatic systems and tools that operate under high pressures. The potential dangers of compressed air include the risk of sudden release, which can cause injury through projectile debris, as well as the potential for over-pressurization leading to equipment failure. Moreover, compressed air can lead to barotrauma if it enters the body through unintended pathways.

While thermal exposure, sunlight, and radiation can pose risks in certain contexts, they are less frequently encountered or specifically hazardous in typical aircraft structures environments compared to the direct and immediate risks associated with compressed air. Therefore, the significant role that compressed air plays in operations and maintenance makes it a primary hazard to consider in safety protocols.