Which hand signal is standard for lowering the boom according to OSHA?

The standard hand signal for lowering the boom, as recognized by OSHA, is indicated by extending the arm horizontally to the side with the thumb pointing down. This signal is clear and easily understood, allowing operators and crane operators to effectively communicate the need for the boom to descend. Using this specific gesture minimizes the potential for miscommunication on the job site, which is crucial in maintaining safety during lifting operations.

In the context of the other choices, waving one hand in a circular motion is commonly used to signal a different action, such as a warning or a stop. Raising both hands above the head could suggest various commands but is not specific to lowering the boom and might lead to confusion. Lastly, moving fingers back and forth with fingers spread is also used for other commands, but does not specifically indicate that the boom should be lowered. Therefore, understanding and using the approved signal is essential for safety and effective communication in construction and lifting operations.