There are four types of signs:
Mandatory signs:
Tell you to use the correct type of protection to avoid accidents. This protection is obligatory. >BLUE CIRCLES
Danger (hazard):
Warn of possible dangers when you use certain materials or tools. >YELLOW TRIANGLES
First aid and Emergency:
Help and give information about first aid and equipment and emergency exits. > IN GREEN and IN RED FOR FIRE
Prohibition:
Forbid certain activities that put your health and others' health at risk. >RED CIRCLES WITH A LINE THROUGH THE PICTURE