Hazard symbols or warning symbols are recognisable

symbol 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 very different conc ...

s designed to warn about hazardous or dangerous materials, locations, or objects, including

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...

poison Poison is a chemical substance that has a detrimental effect to life. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figuratively, with a broa ...

s, and radioactivity. The use of hazard symbols is often regulated by law and directed by

standards organization A standards organization, standards body, standards developing organization (SDO), or standards setting organization (SSO) is an organization whose primary function is developing, coordinating, promulgating, revising, amending, reissuing, interpr ...

s. Hazard symbols may appear with different colors, backgrounds, borders, and supplemental information in order to specify the type of hazard and the level of threat (for example, toxicity classes). Warning symbols are used in many places in lieu of or addition to written warnings as they are quickly recognized (faster than reading a written warning) and more commonly understood (the same symbol can be recognized as having the same meaning to speakers of different

language Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which humans communicate, and may be conveyed through a variety of met ...

s).

List 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 A hypodermic needle (from Greek ὑπο- (''hypo-'' = under), and δέρμα (''derma'' = skin)), one of a category of medical tools which enter the skin, called sharps, is a very thin, hollow tube with one sharp tip. It is commonly used w ...

(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 mate ...

History

The biohazard symbol was developed by the

Dow Chemical Company The Dow Chemical Company, officially Dow Inc., is an American multinational chemical corporation headquartered in Midland, Michigan, United States. The company is among the three largest chemical producers in the world. Dow manufactures plastic ...

in 1966 for their containment products. According to Charles Baldwin, an environmental-health engineer who contributed 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 endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ...

'' 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 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 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 ideali ...

. 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 and Christian symbolism, among other areas. The term is also applied to other symbols with a threefold shape. A similar shape with four rin ...

, 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 center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...

of the overlapping part is equal to half the

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

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 the straight line that "just touches" the curve at that point. Leibniz defined it as the line through a pair of infinitely close points on the curve. More ...

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 a closed path that encompasses, surrounds, or outlines either a two dimensional shape or a one-dimensional length. The perimeter of a circle or an ellipse is called its circumference. Calculating the perimeter has several pract ...

of the

equilateral triangle In geometry, an equilateral triangle is a triangle in which all three sides have the same length. In the familiar Euclidean geometry, an equilateral triangle is also equiangular; that is, all three internal angles are also congruent to each othe ...

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 called a pictogramme, pictograph, or simply picto, and in computer usage an icon, is a graphic symbol that conveys its meaning through its pictorial resemblance to a physical object. Pictographs are often used in writing and ...

applied to containers 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 end-use, or on a vehicle during transportation.

GHS symbols and statements

The

United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and be ...

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. Several European countries have started to implement these new global standards, but older warning symbols are still used in many parts of the world.

Europe

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; see European CLP/GHS hazard symbols *

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 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. File:DIN 4844-2 Warnung vor feuergefaehrlichen Stoffen D-W001.svg, Obsolete German symbol File:Hazard F.svg, Highly Flammable symbol File:GHS-pictogram-flamme.svg, CLP/GHS symbol File:ADR33 UN1203.svg, ADR European hazard sign, meaning "highly flammable" (33)—"

gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...

" (1203)

Canada

The Workplace Hazardous Materials Information System, or WHMIS, is

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

's national workplace hazard communication standard.

United States

The US-based

National Fire Protection Association The National Fire Protection Association (NFPA) is an international nonprofit organization devoted to eliminating death, injury, property and economic loss due to fire, electrical and related hazards. As of 2018, the NFPA claims to have 50,000 mem ...

(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 U.S.-based National Fire Protection Association. First "tentatively adopted as a guide" in 1960, and revised sev ...

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 red section denotes flammability. The blue section denotes health risks. Yellow represents reactivity (tendency to explode). The white section denotes special hazard information. One example of a special hazard would be the capital letter W crossed out (pictured left), indicating it is water reactant.

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 Mr. Ouch is a hazard symbol developed by the US’s National Electrical Manufacturers Association (NEMA) to represent electrical hazards. Unlike other high-voltage warning symbols, Mr. Ouch was specifically designed with young children in mind. ...

(depicting an electricity danger as a snarling, spiky creature) and

Mr. Yuk Mr. Yuk is a trademarked graphic image, created by UPMC Children's Hospital of Pittsburgh, and widely employed in the United States in labeling of substances that are poisonous if ingested. Objective To help children learn to avoid ingesting poi ...

(a green frowny face sticking its tongue out, to represent poison) designs in the United States.

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