Which of the following is NOT a requirement in the separation of salon space?

The correct answer is the lack of barriers. In the context of salon space separation, it is essential to establish physical barriers to ensure privacy and compliance with health and safety regulations. This includes measures such as complete partitioning, self-closing doors, and hinged doors, which all serve to create distinct areas within a salon environment. These features help minimize the spread of contaminants, maintain client confidentiality, and adhere to the professional standards set by regulatory bodies. Therefore, a lack of barriers does not align with the necessary requirements for effective separation within salon spaces, making it the correct answer to identify as not being a requirement.