Colors play an important role in helping to ensure workplace safety. Depending on the situation, each color is assigned a different meaning, which allows a person to determine very quickly what type of hazard is in the area. 

There is no single set of rules for the use of safety colors in signs and labels. Standards have been developed by a variety of agencies, such as the International Organization for Standardization (ISO), the American National Standards Institute (ANSI), as well as the U.S. Occupational Safety and Health Administration (OSHA) and National Fire Protection Agency (NFPA). 

In Canada, standards have been harmonized with those developed by these agencies, although there are variations. 

The Canadian Standards Association (CSA) standard Z321contains three types of signs — symbol, symbol with text and text alone. 

There are three main categories of signs — regulatory, warning and information. Each of these has two subcategories. 

Regulatory signs indicate prohibition (such as no smoking) or mandatory requirements (such as the wearing of hard hats). 

Warning signs indicate caution (such as slippery surfaces) or danger (such as an explosives storage area). 

Information signs indicate emergency facilities (such as exit routes and first aid stations) or general information. 

The CSA standard also contains graphic requirements for signs (shapes, images and text, as well as colors). The colors are: 

Red — Prohibition and Danger. 

Yellow — Caution. 

Green — Location of emergency facilities. 

Blue — General information. 

Black — Prohibition, Mandatory Requirements and Caution. 

Dark Grey — The background color for symbol signs with text. 

In the United States, the comparable standard is ANSI Z535. This is the color code widely used in the U.S., based on the ANSI standard: 

Red — Danger or stop (containers of flammable liquids, emergency stop bars and buttons, fire protection equipment). 

Fluorescent orange and orange-red — Biosafety (Labels and containers for blood and infectious waste.) 

Yellow — Caution (Physical hazards that might result in striking against, falling, tripping or being caught between objects. Also used to mark cabinets and containers for hazardous materials.) 

Orange — Warning (Parts of machinery that might cut, crush or otherwise injure. Inside of transmission guards for pulleys, gears, etc.) 

Green — Safety (Location of first aid equipment, respirators, safety showers, emergency exits etc.) 

Blue — Information (Signs and bulletin boards. Often used to indicate what items of personal protective equipment are required.) 

Black, White, Yellow or combination of Black with White or Yellow — Boundaries (Traffic or housekeeping markings. Stairways, directions and borders.) 

Magenta or Purple on Yellow— Radiation Caution (X-ray, alpha, beta, gamma, neutron and proton radiation.) 

The format of an ANSI safety sign (adopted by OSHA) has three important elements: 

•  Safety Headers and Signal Words (danger, warning, caution, notice, or safety instructions). 

•  Safety Symbols 

•  Sign Legends (describe the hazard or policy to which the sign refers). 

The ANSI standard also deals with sign size, text size and viewing distances as suggested best practices.