Final answer:
Handrails on scaffolds are required by OSHA when workers are subject to falls of 10 feet or more, as part of the fall protection safety standards.
Step-by-step explanation:
Handrails must be installed on all open sides of a scaffold if workers are subject to falls of 10 feet or more. According to the Occupational Safety and Health Administration (OSHA), this is one of the safety measures required to protect workers from the risk of falls.
OSHA regulations detail various safety standards designed to prevent workplace injuries, including the provision of fall protection such as safety harnesses or guardrails on scaffolding to ensure the well-being of employees working at heights.