What do those color coded diamonds on trucks and buildings mean?


The hazards diamond, also known as the hazards icon.



Have you ever seen this posted on a building on a building or a truck and wondered what it was? This colorful symbol is known as the hazards diamond and is a quick way to identify the dangers of chemicals that lurk behind it. It was developed for firefighters but is used extensively by anyone working with chemical reagents.

Each color represents a type of hazard: blue for health, red for fire, yellow for reactivity, and white for anything else you need to know to be able to approach and use this chemical safely. Numbers inside each diamond range from 0 (no risk) to 4 (extreme risk).

Here is each risk shown more specifically,


For example, you might see this near a swimming pool.

Chlorine gas is a deadly health hazard and will oxidize (bleach) powerfully. But it won’t catch on fire or detonate.


And this near propane tanks since propane can be harmful to health if used incorrectly and–as we all know– it can catch on fire easily.



It’s fun to play guess the chemical. At least, it is for me. What do you think this is?is



Now you know what those diamonds mean and remember, they are a chemist’s best friend.



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