Which category is NOT one of the four categories of OSHA standards?

The category that is not recognized as one of the four categories of OSHA standards is safety standards. OSHA (Occupational Safety and Health Administration) classifies its standards primarily into three main categories: performance standards, vertical standards, and horizontal standards.

Performance standards set the desired outcome but allow employers to determine how to meet them. Vertical standards typically apply to specific industries or types of work and outline requirements that pertain to those particular areas. Horizontal standards, on the other hand, are more general and applicable across a variety of industries, focusing on health and safety as it pertains to different types of hazards.

In contrast, "safety standards" is a broad term that can encompass various regulations and practices aimed at ensuring safe working conditions but does not specifically categorize the standards set forth by OSHA. Thus, it does not fit within the defined structure of OSHA's four categories.