Hazard symbols are universally recognized

symbols A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise different concep ...

designed to alert individuals to the presence of

hazardous A hazard is a potential source of harm. Substances, events, or circumstances can constitute hazards when their nature would potentially allow them to cause damage to health, life, property, or any other interest of value. The probability of that ...

or dangerous materials, locations, or conditions. These include risks associated with

electromagnetic fields In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ...

electric currents An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge ...

, toxic chemicals, explosive substances, and radioactive materials. Their design and use are often governed by laws and standards organizations to ensure clarity and consistency. Hazard symbols may vary in color, background, borders, or accompanying text to indicate specific dangers and levels of risk, such as toxicity classes. These symbols provide a quick, universally understandable visual warning that transcends language barriers, making them more effective than text-based warnings in many situations.

List of standardized hazard symbol systems

Examples of common symbols

Tape with yellow and black diagonal stripes is commonly used as a generic hazard warning. This can be in the form of

barricade tape Barricade tape is brightly colored tape (often incorporating a two-tone pattern of alternating yellow-black or red-white stripes or the words "Caution" or "Danger" in prominent lettering) that is used to warn or catch the attention of passersby ...

, or as a self-adhesive tape for marking floor areas and the like. In some regions (for instance the UK) yellow tape is buried a certain distance above buried electrical cables to warn future

groundworker {{Short pages monitor The biohazard symbol is used in the labeling of biological materials that carry a significant health risk, including viral and bacteriological samples, including infected dressings and used hypodermic needles (see

sharps waste Sharps waste is a form of biomedical waste composed of used "sharps", which includes any device or object used to puncture or lacerate the skin. Sharps waste is classified as biohazardous waste and must be carefully handled. Common medical mater ...

History

The biohazard symbol was developed in 1966 by Charles Baldwin, an environmental-health engineer working for the

Dow Chemical Company The Dow Chemical Company is an American multinational corporation headquartered in Midland, Michigan, United States. The company was among the three largest chemical producers in the world in 2021. It is the operating subsidiary of Dow Inc., ...

on their containment products. According to Baldwin, who was assigned by Dow to its development: "We wanted something that was memorable but meaningless, so we could educate people as to what it means." In an article in ''

Science Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...

'' in 1967, the symbol was presented as the new standard for all biological hazards ("biohazards"). The article explained that over 40 symbols were drawn up by Dow's artists, and all of the symbols investigated had to meet a number of criteria: "(i) striking in form in order to draw immediate attention; (ii) unique and unambiguous, in order not to be confused with symbols used for other purposes; (iii) quickly recognizable and easily recalled; (iv) easily stenciled; (v) symmetrical, in order to appear identical from all angles of approach; and (vi) acceptable to groups of varying ethnic backgrounds." The chosen scored the best on nationwide testing for uniqueness and memorability.

Geometry

All parts of the biohazard sign can be drawn with a

compass and straightedge In geometry, straightedge-and-compass construction – also known as ruler-and-compass construction, Euclidean construction, or classical construction – is the construction of lengths, angles, and other geometric figures using only an Idealiz ...

. The basic outline of the symbol is a plain

trefoil A trefoil () is a graphic form composed of the outline of three overlapping rings, used in architecture, Pagan and Christian symbolism, among other areas. The term is also applied to other symbols with a threefold shape. A similar shape with f ...

, which is three circles overlapping each other equally like in a triple

Venn diagram A Venn diagram is a widely used diagram style that shows the logical relation between set (mathematics), sets, popularized by John Venn (1834–1923) in the 1880s. The diagrams are used to teach elementary set theory, and to illustrate simple ...

with the overlapping parts erased. The

diameter In geometry, a diameter of a circle is any straight line segment that passes through the centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest Chord (geometry), chord of the circle. Both definitions a ...

of the overlapping part is equal to half the

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

of the three circles. Then three inner circles are drawn in with radius of the original circles so that it is

tangent In geometry, the tangent line (or simply tangent) to a plane curve at a given point is, intuitively, the straight line that "just touches" the curve at that point. Leibniz defined it as the line through a pair of infinitely close points o ...

to the outside three overlapping circles. A tiny circle in center has a

of the radius of the three inner circles, and arcs are erased at 90°, 210°, and 330°. The arcs of the inner circles and the tiny circle are connected by a line. Finally, the ring under is drawn from the distance to the

perimeter A perimeter is the length of a closed boundary that encompasses, surrounds, or outlines either a two-dimensional shape or a one-dimensional line. The perimeter of a circle or an ellipse is called its circumference. Calculating the perimet ...

of the

equilateral triangle An equilateral triangle is a triangle in which all three sides have the same length, and all three angles are equal. Because of these properties, the equilateral triangle is a regular polygon, occasionally known as the regular triangle. It is the ...

that forms between the centers of the three intersecting circles. An outer circle of the ring under is drawn and finally enclosed with the arcs from the center of the inner circles with a shorter radius from the inner circles.

Chemical symbols

A chemical hazard symbol is a

pictogram A pictogram (also pictogramme, pictograph, or simply picto) is a graphical symbol that conveys meaning through its visual resemblance to a physical object. Pictograms are used in systems of writing and visual communication. A pictography is a wri ...

applied to containers and storage areas of dangerous

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

s to indicate the specific hazard, and thus the required precautions. There are several systems of labels, depending on the purpose, such as on the container for transportation, containers for end-use, or on a vehicle during transportation.

GHS symbols and statements

The

United Nations The United Nations (UN) is the Earth, global intergovernmental organization established by the signing of the Charter of the United Nations, UN Charter on 26 June 1945 with the stated purpose of maintaining international peace and internationa ...

has designed

GHS hazard pictograms Hazard pictograms form part of the international Globally Harmonized System of Classification and Labelling of Chemicals (GHS). Two sets of pictograms are included within the GHS: one for the labelling of containers and for workplace hazard warning ...

and

GHS hazard statements Hazard statements form part of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). They are intended to form a set of standardized phrases about the hazards of chemical substances and mixtures that can be translated i ...

to internationally harmonize chemical hazard warnings under the

Globally Harmonized System of Classification and Labelling of Chemicals The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is an internationally agreed-upon standard managed by the United Nations that was set up to replace the assortment of hazardous material classification and labellin ...

. These symbols have gradually replaced nation and region specific systems such as the European Union's

Directive 67/548/EEC The Dangerous Substances Directive (as amended) was one of the main European Union laws concerning chemical safety, until its full replacement by the new regulation CLP Regulation (2008), starting in 2016. It was made under Article 100 (Art. 94 i ...

symbols,Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006.
. ''Article 60''. pp 34. Canada's Workplace Hazardous Materials Information System. It has also been adopted in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

for materials being sold and shipped by manufacturers, distributors and importers. The USA previously did not mandate a specific system, instead allowing any system, provided it had met certain requirements.

Europe

The European Union aligned its regulations with the GHS standards in 2008 with the adoption of

CLP Regulation The CLP Regulation (for "Classification, Labelling and Packaging") is a European Union regulation from 2008, which aligns the European Union system of classification, labelling and packaging of chemical substances and mixtures to the Globally ...

, replacing its existing

symbols during the mid-2010s, and requiring use of GHS symbols after 1 June 2017. Since 2015, European standards are set by: *

CLP regulation The CLP Regulation (for "Classification, Labelling and Packaging") is a European Union regulation from 2008, which aligns the European Union system of classification, labelling and packaging of chemical substances and mixtures to the Globally ...

(2008) for chemical containers, following international GHS recommendations for

pictograms A pictogram (also pictogramme, pictograph, or simply picto) is a graphical symbol that conveys meaning through its visual resemblance to a physical object. Pictograms are used in systems of writing and visual communication. A pictography is a wri ...

, hazard statements, and precautionary statements.Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006.
. *

European Agreement concerning the International Carriage of Dangerous Goods by Road ADR, formally the Agreement of 30 September 1957 concerning the International Carriage of Dangerous Goods by Road is a 1957 United Nations treaty that governs transnational transport of hazardous materials. "ADR" is derived from the French name f ...

(ADR) for additional packaging for transportation. Vehicles carrying

dangerous goods Dangerous goods are substances that are a risk to health, safety, property or the environment during transport. Certain dangerous goods that pose risks even when not being transported are known as hazardous materials ( syllabically abbreviate ...

must be equipped with orange signs, where the upper code number identifies the type of hazard, and the lower code number identifies the specific substance. These symbols cannot be readily interpreted without the aid of a table to translate the numerical codes. * Directive 92/58/EEC sets out standards for safety signage in workplaces, including signage that marks storage areas for hazardous substances. This was amended to remove the 'Harmful/Irritant' sign in 2015, along with a few clarifications and technical updates related to CLP Regulation.

Canada

The Workplace Hazardous Materials Information System, or WHMIS, is

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

's national workplace hazard communication standard, first introduced in 1988, and included eight chemical hazard symbols. This system was brought into alignment with GHS in 2015, with a gradual phase in of GHS symbols and label designs through 15 December 2025. The WHMIS system does deviate from GHS by retaining the former WHMIS symbol for Class 3, Division 3, ''biohazardous infectious materials'', as GHS lacks a biological hazard symbol.

United States

The US-based

National Fire Protection Association The National Fire Protection Association (NFPA) is a U.S.-based international nonprofit organization devoted to eliminating death, injury, property damage, and economic loss due to fire, electrical, and related hazards. , the NFPA claims to have 5 ...

(NFPA) has a standard

NFPA 704 "NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response" is a standard maintained by the United States, U.S.-based National Fire Protection Association. First "tentatively adopted as a guide" in 1960, ...

using a diamond with four colored sections each with a number indicating severity 0–4 (0 for no hazard, 4 indicates a severe hazard). The system was developed in the early 1960s, as a means to warn firefighters of possible dangers posed by storage tanks filled with chemicals. The red section denotes flammability. The blue section denotes health risks. Yellow represents reactivity (tendency to explode). The white section denotes special hazard information, not properly covered by the other categories, such as water reactivity, oxidizers, and asphyxiant gases.

Non-standard symbols

A large number of warning symbols with non-standard designs are in use around the world. Some warning symbols have been redesigned to be more comprehensible to children, such as the Mr. Ouch (depicting an electricity danger as a snarling, spiky creature) and Mr. Yuk (a green frowny face sticking its tongue out, to represent poison) designs in the United States.

Notes

References

External links

Hazchem Guide from The National Chemical Emergency Centre

European Chemicals Bureau

Directive 2001/59/EC

{{Toxicology Pictograms Infographics Occupational safety and health Symbols