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Safety signs

A prohibition sign telling us not to smoke A prohibition sign telling us not to smoke. © Colourbox

The role of safety signs in preventing injuries cannot be overemphasized. Signs make workers aware of dangers and hazards at the work place. Without signs, many employees will not receive necessary advice and warnings. Safety signage should be an essential part of every business safety strategy. However, it is important to choose the best type of signs, related to the specific needs at a given work Place. Issues need to be considered, such as language, content, size, positioning and material. Safety signs and signals are one of the main means for communicating health and safety information.

Sign telling us to use a helmet A mandatory sign, telling us to use a helmet. © Colourbox

There are three main types of safety signs:


- Prohibition signs; used to tell persons what they should not do
- Mandatory signs; used to tell persons to follow certain procedures
- Caution signs; used to make persons aware of dangers


A man with no shoes, and working at an industrial site.He should have seen the mandatory sign telling him to use safety shoes. This man has no shoes, and is working at an industrial site. The risk of being injured in his feet is very high. He should have seen the mandatory sign telling him to use safety shoes. © Colourbox/Pan American Health Organization-PAHO / World Health Organization-WHO

Examples of caution signs

Here, we will show you some examples of signboards that can be put up as warnings. These signs are quite new ones, from a globally harmonized system called Globally Harmonized System of Classification and Labelling of Chemicals (GHS). This is an internationally agreed-upon system, created by the United Nations in 1992. It is not yet fully implemented in many countries. It was designed to replace the various classification and labelling standards used in different countries by using consistent criteria on a global level. Standardizing signage, improves communication about safety issues. Signs relating to chemicals were chosen as an example here, as chemical hazards pose a huge threat for many work places in developing countries. This is illustrated by the figure below, showing an increasing incidence of chemical burns being treated at a hospital in China.

Increasing number of chemical burns from January 2004 to December 2013 at the Quhua Hospital in China. Incidence of chemical burns from a hospital in China.

Reprinted from Burns, Ye, C., Wang, X.,Zhang, Y., Ni, L., Jiang, R., Liu, L., & Han, C., Ten-year epidemiology of chemical burns in western Zhejiang Province, China, 10.1016/j.burns.2015.12.004, Copyright Elsevier and ISBI 2016, with permission from Elsevier. A PDF version of this article may be found in the Download section at the bottom of the page


Acute toxicity sign Acute toxicity. © Colourbox

This sign, showing a skull and crossbones, illustrates a high risk of toxicity. It indicates the presence of toxic agents at this work place. Such a sign can be relevant for laboratories or chemical production areas.


Flame sign Flame. © Colourbox

The next sign shows a flame, and is the sign indicating a potential fire risk. This could be due to presence of flammable gases or chemicals.


Risk of fire due to oxidizers sign Risk of fire due to oxidizers. © Colourbox

Here you see a sign with a flame over a circle. This means there is a risk of fire from oxidizers. The Globally Harmonized System (GHS) of classification and labeling of chemicals has three separate classifications for oxidizers; gases, liquids, and solids. The definitions are very similar in that generally all three provide oxygen to cause or contribute to the combustion of other materials. This sign might be needed, for instance, in chemical production areas.


Be aware of risk of explosions sign Be aware of risk of explosions. © Colourbox

This sign, with an exploding bomb, informs us that there are explosives around. The workers should move very carefully in such areas, or move away from it.


Health hazard sign Health hazard. © Colourbox

This next sign shows there is a chemical health hazard present. This can be used for any toxicological health risk, such as presence of toxic agents affecting certain organs in the body, carcinogenic agents, mutagenic agents, agents affecting reproduction or respiratory sensitizers.


Exclamation mark sign Exclamation mark. © Colourbox

This sign, an exclamation mark, means there is some kind of chemical danger present. It can be used when there is a risk of different types of adverse health effects, such as irritants, toxic agents, agents with narcotic effects.


Corrosion sign Corrosion. © Colourbox

This sign means there are corrosive agents present. There agents may evaporate and harm the skin of a person, or the eyes.


Gas Cylinder sign Gas Cylinder. © Colourbox

This sign means that there is compressed gas present in the area. Workers will then be informed that the cylinder present with this gas can be dangerous. Pushing such a cylinder so it falls, for instance, could lead to an explosion.


A prohibition sign and a caution sign in a laboratory Both a prohibition sign and a caution sign in a laboratory. © Gro Tjalvin

Many different signs exist. It is important that they are placed close to the location where the activity relevant or hazard is, such as this example of a sign for using hand protection, close to a sink in a laboratory. Also the sign on the bucket, showing it contains biohazardous material, is located on the bucket itself, not on a shelf. This is an example of good signage practice.

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This article is from the free online course:

Occupational Health in Developing Countries

University of Bergen

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