Hazard communication at a glance uses the NFPA 704 diamond, which has four colored sections to show different hazard types. The blue section represents health hazard—the potential for injury or illness from exposure. The numbers inside that blue area range from 0 to 4 to indicate severity, with higher numbers meaning greater health risk. Red signals flammability, yellow indicates reactivity, and white covers special hazards or notes (such as oxidizers or water-reactive materials). So for health hazard, you refer to the blue area.

Notification is defined in predetermined procedures. These are the preplanned, organization-wide steps that specify who must be notified, when to notify them, and what information to share. Having this defined in predetermined procedures ensures fast, consistent communication during a hazmat incident, regardless of which team is on scene. It helps avoid delays and confusion that can come from improvising on the fly. While the incident action plan, field manuals, or standard operating guidelines may touch on notification, the fixed, preapproved nature of predetermined procedures makes them the place where the exact notification process is established.

An ignition source is any energy source capable of initiating combustion of a flammable material. A heated surface fits this role because if a surface is hot enough, vapors emitted by a flammable liquid can reach their ignition temperature simply by contacting it. In other words, the heat from the surface provides the energy needed to start the fire without an open flame. Water won’t ignite anything; it cools and can help prevent ignition. Paper towels are combustible and can burn, but they themselves don’t supply ignition energy—they’re fuel that can burn if an ignition source is present. So, a heated surface is a classic ignition source because it can ignite vapors or fuel materials through heat alone.

The most important idea here is how the NFPA 704 diamond communicates hazards at a quick glance. The diagram uses three colored fields plus a white field. Each colored field carries a number from 0 to 4 that represents the level of hazard: blue is health, red is flammability, and yellow is reactivity. The higher the number, the greater the hazard in that category. The white section is for special hazards and can show symbols indicating things like oxidizers or water reactivity. So, what you see at a glance are the three hazard ratings and any special hazard symbols. You don’t get packaging or shipping information from the NFPA 704 diamond, nor does it list inhibitors. That’s why the at-a-glance information best described is the health, flammability, and reactivity hazards with a white section for special hazards.