Final answer:
In the NFPA 704 Hazard Identification System, the color that signifies a health hazard is blue. This blue diamond is located on the left side of the hazard diamond and includes a rating scale for the substance's health risks.
Step-by-step explanation:
The National Fire Protection Association (NFPA) 704 Hazard Identification System is a standardized label designed to provide quick and easy hazard information on substances. The system features a diamond with four color-coded sections representing different types of hazards. A phlebotomist or any other professional looking to identify health hazards on this label should look at the blue section, which is on the left side of the diamond. According to the NFPA 704 system, the blue diamond represents the health hazard of the substance. This area is rated on a scale from 0 (no hazard) to 4 (extremely hazardous) to indicate the severity of the health risk the substance poses.