Caution and Warning Signs

Updated July 15, 2024

Caution Signs are required to be posted at the entrance to a space where hazardous materials are stored or used. The Caution sign is based on a location's chemical inventory; it alerts emergency responders and visitors of potential hazards and precautions for entry.

Warning Signs alert personnel and visitors to health and safety hazards beyond those identified in the caution sign. Specific warning signs may be required based on the type of hazard present.

Sample Caution Sign

Caution Signs

Laboratories, shops and maker spaces where hazardous materials are used or stored are required to post an up-to-date Caution Sign at the entrance.

A Caution Sign is required to be posted in a Plexiglas holder above or near the room number placard at each entrance that has a door or barrier.

The purpose of the Caution Sign is to warn emergency responders and visitors of potential hazards in the space and to meet multiple regulatory requirements. The Caution Sign consolidates signage requirements for National Fire Protection Association (NFPA) 704 Hazardous Materials, biohazardous and radioactive materials authorization, entry requirements, food and drink prohibitions and lab contact information.

Hazards listed for that location include all items listed in MyChem, the University’s chemical inventory database.

Caution Sign instructions

Warning Signs

Warning Sign(s) may be required to be posted in the area where a potential hazard is present, including biohazards, compressed gases, lasers, lead, liquid nitrogen, magnetic fields, radioactive materials, ultraviolet lights and x-rays.

Spill and Exposure Response Posters

Post the Spill Response Poster and Exposure Response Poster (as applicable) in your workspace for quick reference in case of a hazardous material spill, release or exposure.

Services available

Sign holders for Caution signs are provided by Environmental Health & Safety (EH&S) and available upon request by emailing

Please read the FAQ section below or contact EH&S if you have questions about creating a Caution sign.

EH&S is available for consultation on selecting the appropriate warning signs for the specific hazards in your work area.

Frequently asked questions

More Information


Laboratory Safety Contact

(206) 685-3993
Reference Files