Which safety regulation must all rail mechanics adhere to in the workplace?

All rail mechanics must adhere to the Occupational Safety and Health Administration (OSHA) standards in the workplace because these regulations are specifically designed to ensure the safety and health of employees across various industries, including rail mechanics. OSHA standards encompass a wide range of safety practices, including proper handling of hazardous materials, safe use of equipment, and protocols for maintaining a safe work environment.

By following these regulations, rail mechanics can effectively minimize the risk of workplace injuries and accidents, which is vital in a field that often involves heavy machinery and potentially hazardous conditions. While the other options—such as EPA standards, DOT guidelines, and FRA regulations—are important in their own contexts, they do not focus specifically on the overall safety and health conditions of workers in the same detailed manner that OSHA does.