The federal Occupational Safety and Health Act (OSH Act) is “preemptive”; that is, it overrides state laws and regulations in the areas that it covers. Since it covers virtually all areas of workplace health and safety in the private sector, it supplants most state work-safety requirements. Under the OSH Act, individual states may devise and administer their own standards, but only with federal approval and only if the applicable state requirements are as stringent as the corresponding federal standards.
Pennsylvania does not have an approved state program, making federal requirements the governing law for private sector workplaces. A comprehensive discussion of the federal standards is available.