Many people would immediately associate hazard signs with businesses that sell or use dangerous chemicals.  It is common to see them in many areas in an industrial compound because just about every industry must use chemicals and other types of materials that are dangerous.  If one is exposed to them without protective equipment in place or if they use them in an unapproved method, it could result in extreme injury or even cause a fatality.

Hazard signs are also necessary for areas where there is high voltage electricity being used.  This can be in many places within a city or a neighborhood and even in buildings.  It is necessary to warn of the high voltage as it can be deadly if it is tampered with or if exposure to it is experienced without the proper safety precautions in place.

Hazard signs are also found near bodies of water.  They may indicate that the area is not safe to swim in and that there are heavy undercurrents such as those found at a reservoir.  It may be that the body of water is used for filtration of heavy chemicals, and it would not be safe to be immersed in.  There can also be warning placards to designate the body of water as not being safe in the winter time for ice skating or walking on. 

Hazard signs are found at gas stations throughout the country.  These placards remind motorists that it is not safe to fill the tank with the engine running.  They also warn not to use cellular phones while filling the tank because the device could cause flammable vapors to ignite and cause an explosion or fire.  There are placards that warn customers not to smoke while pumping gasoline.

Hazard signs are also found on vehicles that transport the various different types of chemicals and gases.  These are required by state and federal laws.  These clearly show what type of chemical is inside the tanker, the flammability of the gas or chemical, and the protective equipment that must be worn in order to remain safe while handling the materials, gases, or chemicals.  Within a vehicle of this type, there will also be a MSDS sheet which is a piece of information that explains what the health risks are to the persons who may have been exposed to it as well as the precautions to take in the event of a spill or accidental leakage.

Within a factory or industrial area, there are many types of precautionary labels and placards that are required to be placed, and these are monitored by state and federal agencies such as the Occupational Safety and Health Administration, the Environmental Protection Agency and other types of organizations that are watchdogs to make sure that the citizens and the environment are all being carefully informed and protected against disaster. 

Without these types of warnings, there may not be any way for a person to know that there is a risk of exposure or harm until it is too late.