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Everyday exposure in construction.

Hazard Categories


In the first module, we began a discussion of the concepts of "hazard" and "exposure" in preparation for a further look in this module. Here we will take a closer look at the five general hazard categories and 13 more specific hazard categories. All this will help you improve your knowledge and skills in proactive hazard identification to help eliminate hazards in the workplace.

Five General Hazard Areas

Just remember MEEPS!

All workplace hazards exist in five general areas. You can remember them by using the mnemonic, "MEEPS". Here are some examples:

  • Materials - liquids, solids, gases, etc.
  • Equipment - includes machinery, tools, devices
  • Environment - noise, radiation (non-ionizing and ionizing), humidity, temperature, atmospheres, workstation design
  • People - anyone in the workplace (i.e., employees, guests, customers or contractors)
  • System - flawed policies, programs, plans, processes, procedures, and practices

"Recognized" Hazards

Inspect to find hazards.

When you conduct a walkaround inspection you are usually looking for hazardous materials, equipment, and environmental factors. These first three hazard areas represent hazardous physical conditions (think of these as hazardous "states of being") in the workplace which, according to various studies*, cause only about three percent of all accidents in the workplace. It's interesting to note, that hazardous conditions are what OSHA inspectors primarily cite as violation. What does that mean? Well, OSHA is very good at uncovering the conditions that don't cause many accidents. It's a flawed system, but it's all we have. That also explains why there is little correlation between the most frequently cited violations and the most frequent causes of injury.

Sober and Focused

The fourth category, "People," refers to any employee (or others) at any level of the organization who may not be "sober and focused" on the work they're doing. For example, an employee might be in a hazardous "state of being" if they are:

  • under the influence of legal/illegal drugs;
  • poorly trained or educated;
  • worried about a family illness;
  • mentally or physically incapable of doing the job safely; or
  • not focused on their work - distracted.

Remember, an employee who is distracted in any way from the work they're doing should also be considered a "walking" hazardous condition that increases the likelihood of an unsafe behavior. Today, distraction is becoming a big problem with the use of cell phones, especially while people are walking or driving. Unfortunately, OSHA does not usually "catch" employees working in an unsafe manner, so you don't see unsafe behaviors described in OSHA citation reports too often.

The safety management system is composed of policies, programs, plans, processes, procedures and practices that influence or contribute to behaviors in the workplace. A flawed system will contribute to some degree to workplace conditions and behaviors. Therefore we can argue that the safety management system is ultimately the cause for up to 98 percent of the accidents that occur in the workplace!

* SAIF Corporation, Oregon

Hazardous Materials

Every workplace has hazardous materials.

Nearly every production job involves the use of hazardous materials including chemicals for cleaning, stripping, or degreasing parts and equipment. Maintenance workers who enter enclosed or confined spaces are also exposed to toxic substances.

Solvents: Solvents are used to dissolve various materials. Those commonly used include:

trichloroethylene toluene
acetone methylene chloride
percholoroethylene glycol ether
isopropyl alcohol Chloroform
xylene freon

Exposure occurs by inhalation, ingestion, and absorption primarily through skin contact. Skin exposure may result in dermatitis or skin rash, edema or swelling, and blistering. These exposures can result from chemical splashes and spills, from directly immersing one's hands into solvents and chemicals, from contact with solvent-soaked clothing or solvent-wet objects, and from the use of improper personal protective equipment. Solvents can dissolve the body's natural protective barrier of fats and oils leaving the skin unprotected against further irritation.

In addition, inhaling or ingesting solvents may affect the central nervous system, acting as depressants and anesthetics causing headaches, nausea, drowsiness, dizziness, complaints of irritation, abnormal behavior, general ill-feeling, and even unconsciousness. These symptoms should be viewed as visible signs of potential disease. Excessive and continued exposure to certain solvents may result in liver, lung, kidney, and reproductive damage, as well as cancer.

Acids and Alkalis: Acids and alkalis may cause serious burns if they are splash into the eyes or onto the skin. If vapors or mists are inhaled, they may result in a burning of the linings of the nose, mouth, throat, and lungs.

Metals: Employees are exposed to metals primarily by skin contact and by inhalation of metal dusts and fumes. Exposure may cause headaches, general ill-feeling, anemia, central nervous system and kidney damage, and reproductive problems, as well as cancer.

Gases: Gases are used in many operations and may combine with other substances to produce toxic gases such as phosgene, ozone, and carbon monoxide. Workers can be exposed to these and other gases during work. Potential exposure to gases occurs through inhalation. Such exposure may produce eye damage, headaches, shivering, tiredness, nausea, and possible kidney and liver damage.

Plastics and Resins: Inhalation or skin contact may occur when curing resins; cutting, heating, or stripping wires; or cutting, grinding, or sawing a hardened product. Exposure to these substances may result in skin rash and upper respiratory irritation.

Polychlorinated Biphenyls (PCBs): PCBs are used as insulators in some electrical equipment and present a potential hazard to workers. Exposures to PCBs may cause skin disorders, digestive problems, headaches, upper respiratory irritations, reproductive problems, and cancer.

Fiberglass and Asbestos: Fiberglass and asbestos are also used as fillers in epoxy resins and other plastics, in wire coatings or electrical insulation, and in printed circuit boards. Uncontrolled exposures may produce skin and upper respiratory irritations and, in the case of asbestos, cancer.

Solids: Solids like metal, wood, plastics. Raw materials used to manufacture products are usually bought in large quantities, and can cause injuries or fatalities in many ways.

Gases: Gases like hydrogen sulfide, methane, etc. Gas may be extremely hazardous if leaked into the atmosphere. Employees should know the signs and symptoms related to hazardous gases in the workplace.

Heavy equipment is always dangerous.

Hazardous Equipment

Hazardous equipment includes machinery and tools.

  • Hazardous equipment should be properly guarded so that it's virtually impossible for a worker to be placed in a danger zone around moving parts that could cause injury or death. A preventive maintenance program should be in place to make sure equipment operates properly. A corrective maintenance program is needed to make sure equipment that is broken, causing a safety hazard, is fixed immediately.
  • Tools need to be in good working order, properly repaired, and used for their intended purpose only. Any maintenance person will tell you that an accident can easily occur if tools are not used correctly. Tools that are used while broken are also very dangerous.
Work environments can be very hazardous.

Hazardous Work Environments

Are there areas in your workplace that are too bright, dark, hot, cold, dusty, dirty, messy, wet, etc.? Is it too noisy, or are dangerous gases, vapors, liquids, fumes, etc., present? Do you see short people working at workstations designed for tall people? Such factors all contribute to an unsafe environment. You can bet a messy workplace is NOT a safe workplace!

Noise Exposure: Many work places are inherently noisy and potentially hazardous to employees. Continuous noise and instantaneous noise bursts can damage the hearing of employees. A hearing conservation program should be established if you think noise levels are a potential threat to the health of your employees. OSHA consultants, your insurer, or a private consultant are all available to help you determine noise levels in the workplace.

Electric Shock: Electricity travels in closed circuits, normally through a conductor. Shock occurs when the body becomes part of the electric circuit. The current must enter the body at one point and leave at another. Shock normally occurs in one of three ways. The person must come in contact with:

  • both wires of an electric circuit,
  • one wire of an energized circuit and the ground, or
  • a metallic part that has become "hot" by being in contact with an energized wire or conductor, while the person is also in contact with the ground.

Illumination: It's important to make sure illumination is adequate for the job being performed. Too much direct or indirect glare can, over time, cause eye strain. Too little light can result in an injury. More on this topic in course 711, Introduction to Ergonomics.

People can be "walking hazards".

Hazardous People

Remember, hazardous conditions may be thought of as unsafe "states of being." All of the following situations may cause employees to be what I call "walking hazards"

  • Fatigue: Employees are too tired to do the work without causing injury to themselves or others.
  • Drugs or alcohol: Drugs (either legal or illegal) and alcohol place employees in altered states of awareness and lengthens reaction time.
  • Distraction: Employees who are distracted (internal thoughts are not focused on the work being performed). You can't be thinking about the football game while working on high voltage!
  • Hurry: This should be obvious. This is probably the greatest reason employees perform unsafe actions. The more hurried employees are, for whatever reason, the more likely they are going to have accidents.

Workers who take unsafe short cuts, or who are using established procedures that are unsafe, are accidents waiting to happen. As mentioned earlier, hazardous work practices represent about 95% of the causes of all accidents in the workplace. Bottom-line: If employees are not sober and focused while working, they are walking hazardous conditions.

  • Management may unintentionally promote unsafe work practices by establishing policies, procedures and rules (written and unwritten) that ignore or actually direct unsafe work practices. These safety policies, plans, programs, processes, procedures and practices are called "system controls" and ultimately represent the causes of about 98% of all workplace accidents.

Hazardous System

Every company has, to some degree, a safety management system. Management may unintentionally promote unsafe behaviors by developing ineffective policies, procedures and rules (written and unwritten) that ignore safe behaviors or actually direct unsafe work practices. Safety policies, plans, programs, processes, procedures and practices are called "Administrative Controls," and they ultimately represent the causes for about 98% of all workplace accidents.

13 Hazard Categories

Safety Memo - Accidents: Six Causes.

The following 13 hazard categories are adapted from Product Safety Management and Engineering, by Willie Hammer, ASSP Pub. This publication is an excellent text to add to your library.

  1. Acceleration: This is just a fancy term for "fall" hazard. Acceleration happens when we speed up or slow down too quickly. It also occurs when any object is being set in motion or its speed increased. Whiplash is a common injury as a result of an acceleration hazard. Hazards from deceleration and impact, especially from falls, also exist in the workplace.
  2. Biohazards: Hazards of harmful bacterial, viruses, fungi, and molds are becoming a greater concern to everyone at work. The primary routes of infection are airborne and bloodborne.
  3. Chemical reactions. Chemical reactions can be violent, and can cause explosions, dispersion of materials and emission of heat. Chemical compounds may combine or break down (disassociate) resulting in chemicals with reactive properties. Corrosion, the slow combination of iron and water, is a common chemical reaction and results in loss of strength and integrity of affected metals.
  4. Electrical hazards: Exposure to electrical current. There are six basic electrical hazards: shock, ignition, heating/overheating, inadvertent activation (unexpected startup), failure to operate, and equipment explosion.

13 Hazard Categories (Continued)

Strains and sprains are very common.
  1. Ergonomics: The nature of the work being done may include force, posture, position of operation characteristics that require hazardous lifting, lowering, pushing, pulling, and twisting. The results are strains and sprains to muscles and connective tissues.
  2. Explosives and explosions: Explosions result in quick (instantaneous) releases of gas, heat, noise, light and over-pressure. High explosives release a large amount of energy. Low explosives burn rapidly (deflagrates) but at a slower speed. Most explosive accidents are caused by explosions of combustible gases.
  3. Flammability and fires: In order for combustion to take place, the fuel, an oxidizer, and ignition source must be present in gaseous form. Accidental fires are commonplace because fuel, oxidizers and ignition sources are often present in the workplace.
  4. Temperature: Temperature indicates the level of sensible heat present in a body. Massive uncontrolled flows of temperature extremes due to work in hot or cold environments can cause trauma and/or illness.
Hyperthermia is dangerous.

13 Hazard Categories (Continued)

  1. Mechanical hazards: Tools, equipment, machinery and any object may contain pinch points, sharp points and edges, weight, rotating parts, stability, ejected parts and materials that could cause injury.
  2. Pressure: Increased pressure in hydraulic and pneumatic systems. Pressure may cause ruptures in pressure vessels, whipping hoses. Small high pressure leaks may cause serious injuries.
  3. Radiation: Electromagnetic radiation hazards vary depending on the frequency (wavelength) of the energy. Generally, the higher the frequency, the more severe the potential injury. Non-ionizing (ultra-violet, visible light) may cause burns. Ionizing radiation actually has the potential to destroy tissue by dislodging electrons from atoms making up body cells.
  4. Toxics: Materials that in small amounts may cause injury to skin and internal organs are considered toxic. Toxics may enter through inhalation, ingestion, absorbed or injected.
  5. Vibration/Noise: Produce adverse physiological and psychological effects. Whole-body vibration is a common hazard in the trucking industry. Segmental vibration and noise hazards exist when working equipment such as jack hammers.


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. According to the text, the safety management system may contribute to as much as ____ percent of the accidents that occur in the workplace:

2. Which of the following is not discussed as one of the five (MEEPS) general hazard categories?

3. According to SAIF Corporation, ____________ are the cause of about 3% of all accidents in the workplace:

4. Which of the following could result in the employee being a "hazardous condition"?

5. This type of hazard is inherent in any job requiring employees to work at any height above ground level:

Have a great day!

Important! You will receive an "error" message unless all questions are answered.