Which item is essential for a mechanic when working in an area where noise levels are high?

Hearing protection is essential for a mechanic working in a noisy environment because prolonged exposure to high noise levels can lead to permanent hearing loss or damage. In many mechanical settings, tools and machinery generate significant sound that can exceed recommended exposure limits, making it critical to protect one's hearing. Using earplugs or earmuffs specifically designed for hearing protection can help mitigate these risks.

The other options, while important for safety, do not address the specific hazard of noise exposure. Safety glasses protect the eyes from flying debris and other hazards, a hard hat guards against head injuries from falling objects, and steel-toed boots provide foot protection from heavy items. Each of these items plays a role in overall safety but does not specifically address the risk of hearing loss in a high-noise setting.