Why is it important that everyone use the same hazard symbols?
So that they can be recognised by as many people as possible – just like road signs. Fire Exit signs for example have been redesigned over recent years to make them harmonise with symbols understandable across the EC – so you only have one set of symbols to learn and understand – without needing to know the language. They also need to be obvious even if you haven’t seen them before and be instantly understood if they are to be any use – no good umm-ing and ahh-ing about what it means if the acid or whatever is corroding your boots.
