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Essential Laboratory Safety Signage

By Ken Roy

Posted on 2021-08-09

I. Expectation for Laboratory Safety Signage

Occupational Safety and Health Administration’s (OSHA) Occupational Exposure to Hazardous Chemicals in Laboratories Standard (29 CFR 1910.1450), often referred to as the Laboratory Standard, requires science laboratories to develop a Chemical Hygiene Plan (CHP). Appendix A of 1910/1910.1450 involves the National Research Council (NRC) Recommendations Concerning Chemical Hygiene in Laboratories (Non-Mandatory). Its purpose is to help employers develop an appropriate laboratory CHP. The non-mandatory recommendations were based on the NRC’s 2011 edition of Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards. Section D, part 7, deals with signage in labs. What are the signs or placards that should be posted in labs for employee (and student) safety?

II. Signage Categories That Should Be Posted

Section D, part 7, specifically notes that prominent signs of the following types should be posted in academic science/STEM (science, technology, engineering, math) labs:
(a) Emergency telephone numbers of emergency personnel/facilities, supervisors, and laboratory workers. This includes how to dial out for emergency services from an in-class phone. Do not rely on your cell phone, as you may find yourself in a classroom or office without cell reception.
(b) Location signs for safety showers, eyewash stations, other safety and first aid equipment, and exits
(c) Warnings at areas or near equipment where special or unusual hazards exist.

III. Classification of Signs and Requirements

Examples of sign classification and requirements based on their need or purpose in laboratories are as follows:

A. General Safety Signs
General safety signs are found throughout the school, including science/STEM labs. These signs are used for general safety measures requiring notification. An example might be “Keep books/backpacks off the floor to prevent trip/fall hazards!”

B. Danger Signs 
Danger signs are required if an immediate hazard exists. Special precautions are required, given the potential for an immediate danger. Danger signs by design require colors of red, black, and white only. Examples might include the following:
“DANGER—CORROSIVE LIQUIDS, Wear Protective Equipment” 

C. Warning Signs
Warning signs are required if the potential for a hazardous situation exists. If not avoided, it might result in serious injury or death. Examples might include the following:
“WARNING—Saw Blade Guard Required! 
“WARNING—Flammables—No active flames allowed!

D. Caution Signs
Caution signs are required to warn against potential or possible hazards or to caution against unsafe practices. Proper precautions must be exercised. The standard sign color for the background is yellow. The panel requires black with yellow letters. Any letters used against the yellow background must be black. Examples might include the following:
CAUTION: Watch your step! 
CAUTION: Appropriately Dispose of Hazardous Chemicals!
CAUTION: Safety Goggles Required!

E. Biological Hazard Signs
Biohazard warning signs are required to be posted in laboratories containing biohazardous agents or potentially infectious materials. The biohazard symbol design is fluorescent orange or orange-red color. Background color is optional as long as there is sufficient contrast for the symbol to be clearly defined. Appropriate wording may be used in association with the symbol to indicate the nature or identity of the hazard, name of individual responsible for its control, precautionary information, etc., but this information must not be superimposed on the symbol. An example might include the following:
Caution: Biohazard Present!

F. Radiation Warning Signs
Radiation warning signs are required to indicate the types of exposure levels that may be present in the lab or area. Magenta or black on a yellow background are the internationally recognized colors used to signify the presence of ionizing radiation. A trefoil symbol is used. Examples might include the following:
CAUTION—Radioactive Materials

G. Laser Hazard Signs
Laser hazard warning signs indicate the actual or potential laser light hazard in the laboratory. An example might include the following:
CAUTION—Laser Eyewear Must Be Worn! 
H. NFPA Signage
National Fire Protection Association (NFPA) 704 placards are required warning signs to be posted on entering labs, storerooms, etc., where a fire hazard may be present. They are intended to give emergency responders the information they need to determine the immediate actions to be taken in an emergency.  

Additional signage information can be found at California Institute of Technology Laboratory and Workplace Safety Signs at

IV. Common Signage for Grades 7–12 Science/STEM Labs

The following examples of safety signage are recommended, and in most cases, legally required for grades 7–12 science/STEM labs.

A. Personal Safety Signs
Safety First—Wear Your Goggles
Safety First—Save Your Eyes; Wear Eye Protection
Stop! Think! Hygiene! Wash hands!
Caution: Laser in Use—Serous Eye Damage May Occur. Wear Eye Protection in this area. (Note: Check local, county, and state regulations before purchasing or using a laser in a K–12 setting. This includes laser pointers.)
Laser in Use—Do Not Stare Into Beam! (Note: Check local, county, and state regulations before purchasing or using a laser in a K–12 setting. This includes laser pointers.)
Safety First: Goggle Storage Center
Food and Drink Prohibited!
Emergency Contact Numbers for Nurse, Fire/Police Departments, Administration, etc., including instructions on how to dial these numbers. Ex. Dial 9, then 9-1-1.

B. NFPA Signs
Fire Extinguisher
Exit only
No Open Flames
NFPA 704 Diamond Sign
High Voltage
Electrical Hazard
Notice: Chemical Spill Control Center

C. First aid signs
First Aid Kit
Fire Blanket
AED Defibrillator (automated external defibrillator)
Safety First—safety shower and eyewash station
Emergency Shower

D. Engineering Controls
Emergency Gas Shutoff valve
Emergency Electrical Shutoff valve
Emergency Water Shutoff valve
Danger! Do Not Operate Without Guards in Place
Danger! Do Not Remove Guards!
Caution! Handle Hazardous Chemicals Under Fume Hood Only!

E. Chemical Storeroom
Notice—authorized personnel only
Danger—keep out
Remember these examples of signage are generic. It is important that you also check your local municipality, county, or state regulations regarding specific signage in the classroom/laboratory. For example, when science rooms/laboratories are inspected by local and state fire marshal officials, the following may be required to be in place:

•    Emergency exit routes/maps by each door. This includes the secondary door in the back of the lab and any door(s) connecting the prep room to the classroom.
•    Light-up Exit Signs with flood lights and battery backup in case power is out during an emergency. It should be obvious where the exit doors are located, even in the dark. 
•    If gas is available in the room, a red sign with white letters must indicate where the emergency gas shutoff is located. Additionally, each gas pipe must be labeled with the C.A.S. (Chemical Abstracts Service) number of the gas in the pipe.
•    If goggles are used in the room, a yellow sign with black lettering must indicate that goggles must be worn.
•    The following four items must have a sign indicating their location: Fire Blanket, Eyewash Station, Safety Shower, and Fire Extinguisher. The inspection log should be attached to each device so anyone can determine if the inspections are up to date and the equipment is working. 
•    The Fire Alarm with directions on how to activate it in an emergency.
•    If a refrigerator or a microwave are in the laboratory or the prep room, it must have a sign indicating “For Lab Use Only! No food or drink permitted.”

Knowing which signs are required will make the inspection process easier. For more information, contact your local Fire Marshal.

Additional signs should include the following:
•    Students are not permitted in the prep room.
•    Signs on lab faucets indicating whether they carry gas, hot water, or cold water.

V. Final Words

Safety signage is necessary not only for reminders and raising levels of awareness, but also especially for emergency responses during a safety incident. Before starting lab activities, make sure your lab has the appropriate signage for safer teaching/learning activities. Also be aware that the use of a safety sign does not override district, municipality, county, or state regulations; e.g., the use of lasers in the classroom.

VI. Reference

Lab Health and Safety—Science Laboratory Safety Symbols and Hazard Signs, Meanings by Lab Manager

Submit questions regarding safety to Ken Roy at, or leave him a comment below. Follow Ken Roy on Twitter: @drroysafersci.

Safety Blog Acknowledgement—NSTA Chief Safety Blogger Dr. Ken Roy wishes to sincerely thank nationally recognized District Supervisor of Science Kevin S. Doyle, Ed. D., Morris Hills Regional District, Rockaway, New Jersey ( for his professional review of this commentary.

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