The basic purpose of a safety sign is to alert someone to a policy or potential hazard with enough time to take action and ensure their own safety.
With that as a goal, basic requirements of safety signs should be displaying elements that gain the attention of onlookers in a clear and concise way.
This could be fulfilled by the use of bold colors, clear messages, or universally understood imagery.
The Occupational Safety and Health Administration (OSHA) sets and enforces safety standards for most workplaces in the country, and has developed specific definitions for the types of safety signage that should be used in the workplace.
ANSI has updated their standards for the required design of accident preventions signs (safety signs), and OSHA has recently incorporated these standards.