Recognize the Warning Signs

In an effort to decrease the number of accidents and injuries in the workplace, OSHA developed two standards on safety color-coding and specifications for accident prevention signs and tags. A sign refers to a surface on prepared for the warning of, or safety instructions of, industrial workers or members of the public who may be exposed to hazards. The information is located in 29 CFR 1910.144 and 1910.145.

What must I know?

There are a few different means of designating signs and tags. Color and shape work well for the purpose of communicating required information. The American National Standards Institute (ANSI) has developed the following color scheme:

Safety colors:

  • Red - Fire, danger, or stop
  • Orange - Warning
  • Yellow - Caution
  • Green - Safety
  • Blue - Notice


  • Triangle - Hazard alerts
  • Circle - Mandatory actions
  • Square/rectangle - Information
  • Circle with slash - Prohibited activity

According to the National Electrical Manufacturer’s Association/American National Standards Institute (NEMA/ANSI), the lettering must be in upper case block letter, and large enough that a person with normal vision can read it. The labels on piping also play a vital role in informing employees and emergency personnel what is contained in the pipes in your workplace. These labels are color-coded and include the substance name.

Labels on piping:

  • Yellow - Flammable
  • Green - Liquid, non-flammable
  • Blue - Gaseous
  • Red - Fire quenching material

Adequate lighting should be available for signs so that the message is readable. Your employer strives to maintain the safest workplace possible, and the communication of hazards plays an important role. Knowing the difference between red and green may sound simple, but it could save a life.