Occupational Safety and Health Administration (OSHA) regulations only apply to federal employees unless:

A state jurisdiction decides to adopt them as a part of local regulations.

Explanation:

Occupational Safety and Health Administration (OSHA) is an agency of the United States Department of Labor. It was created by the Congress, with the main goal of securing decent working conditions for all citizens of the United States. Federal government is responsible for covering all public sectors employees, and most of workers in private companies. If, for example, there are unsafe working conditions, workers may file a complaint to the OSHA and request an inspection of the working place. Additional steps need to be fulfilled in order to prove that there is a need for OSHA to take actions. States are responsible for applying regulations about OSH protection in both public and private sector. In conclusion, if the state decides to apply regulations and local regulations, they will also be applied for the federal employees.