Which four hazards does the NFPA 704 system identify?

The National Fire Protection Association (NFPA) 704 system is a color-coded system designed to quickly communicate the hazards associated with materials. The correct identification of hazards includes four key categories: Health, Fire, Reactivity, and Special Hazards.

The Health hazard indicator assesses the potential for harm to health, providing a numerical rating that reflects the severity of exposure risks. The Fire hazard indicator focuses on how easily a substance can ignite, highlighting its flammability. The Reactivity indicator indicates how stable a substance is under normal conditions and its potential to react violently with other substances. Lastly, the Special Hazard indicator denotes specific hazards that don't fall under the other categories, such as radiation or acid/alkali hazards.

The other options mentioned do not accurately represent the four hazards classified by the NFPA 704 system. For instance, while "Environmental" is an important consideration in hazard assessments, it is not included in the NFPA 704 categories. Similarly, terms like "Toxicity" and "Biological" are aspects of hazard evaluation but do not align with the NFPA's primary classification focus. The NFPA's structured approach allows emergency responders to make quick decisions for safety and mitigation based on visual cues provided by the system.