Introduction

You've gathered information and used it to develop an accurate sequence of events. You have a good mental picture of what happened. Now it's time to conduct an analysis of each event to determine causes. This module will introduce us to the concepts below.

• Direct cause of injury
• Surface cause of the accident
• Root cause of the accident
• Injury analysis
• Surface cause analysis
• Root cause analysis

The harmful transfer of energy is the direct cause of injury

It's important to understand that all injuries to workers are caused by one thing: the harmful transfer of energy. Let's take a look at some examples that illustrate this important principle.

• If a harsh acid splashes on your face, you may suffer a chemical burn because your skin has been exposed to a chemical form of energy that destroys tissue. In this instance, the direct cause of the injury is a harmful chemical reaction. The related surface causes might be the acidic nature of the chemical (condition) and working without proper face protection (unsafe behavior).

• If your workload is to too strenuous, force requirements on your body may cause a muscle strain. Here, the direct cause of injury is a harmful level of kinetic energy (energy resulting from motion), causing injury to muscle tissue. A related surface cause of the accident might be fatigue (hazardous condition) or improper lifting techniques (unsafe behavior).

The important point to remember here is that the "direct cause" of the injury is not the same as the "surface cause" of the accident event.

• The direct cause of injury is the harmful transfer of energy as a consequence of your exposure to that energy. The direct result of this harmful energy transfer is injury.

• The surface cause of the accident is the condition or behavior that interact in a way that results in the harmful transfer of energy.

Safety "engineers" closely analyze all the surface cause categories and attempt to:

• eliminate the harmful energy transfer,
• reduce the harmful energy transfer, or
• reduce exposure to harmful energy transfer.

They do this through "safety by design" by designing safety features directly into tools, machinery, equipment, facilities, etc.

The surface causes of accidents

The surfaces causes of accidents are those hazardous conditions and unsafe or inappropriate behaviors that have directly caused or contributed in some way to the accident.

Hazardous conditions

• Are unique things or objects that are somehow defective or unsafe
• Are "states of being" such as employee fatigue
• May also be unique defects in processes, procedures or practices
• May exist at any level of the organization
• Are the result of deeper root causes

Hazardous conditions may exist in any of the categories below.

Materials Machinery Equipment Tools Chemicals

Environment Workstations Facilities People Workload

Unsafe or inappropriate behaviors

It's important to know that most hazardous conditions in the workplace are the result of the unsafe or inappropriate behaviors that produced them.

• Actions we take or don't take that increase risk of injury or illness
• May also be thought to be unique performance errors in a process, procedure or practice
• May exist at any level of the organization
• Are the result of deeper root causes

Below are some examples of unsafe or inappropriate employee/manager behaviors.

Failing to comply with rules Using unsafe methods Taking shortcuts Horseplay Failing to report injuries Failing to report hazards

Allowing unsafe behaviors Failing to train Failing to supervise Failing to correct Scheduling too much work Ignoring worker stress

Root Cause of the Accident

Now let's switch gears. Instead of talking about unique conditions and behaviors, let's look at the general conditions and behaviors inherent in the safety management system. Oh yes... to me the safety management system is "organic". By that I mean it is dynamic, ever-changing and behaves as though it were alive. Think about it. If that's a little too metaphysical for you... read on.

The root causes for accidents are the underlying safety management system weaknesses, which consist of thousands of variables, any number of which can somehow contribute to the surface causes of accidents. These weaknesses can take two forms. System Design Root Causes. Inadequate design of one or more components of the safety management system. The design of safety management system policies, plans, programs, processes, procedures and practices (remember this as the 6-P's) is very important to make sure appropriate conditions, activities, behaviors, and practices occur throughout the workplace. Ultimately, most surface causes will lead to system design flaws. System Implementation Root Causes. Inadequate implementation of one or more components of the safety management system. Failure to effectively implement the safety management system is critical to the success of the system. You may design an effective safety plan, yet suffer failure because it wasn't implemented properly. If you effectively implement a poorly written safety plan, you'll get the same results. In either instance, you'll eventually need to improve one or more policies, plans, programs, processes, procedures or practices.

Safety managers work with safety engineers to eliminate or reduce exposure to hazards through effectively improving safety system components. Because systems design work common throughout the workplace, eliminating any single root cause may simultaneously eliminate many hazardous conditions and unsafe behaviors.

Since root causes reside within safety management systems, upper management -- those who formulate systems, are most likely going to be involved in making the necessary improvements. When analyzing for system weaknesses, it may be beneficial to coordinate closely with those who will be responsible for implementing system improvements.

If you have Adobe Acrobat, take a look at the Accident Weed, an excellent analogy that helps us understand the relationship between surface and root causes for accidents.

Three levels of cause analysis

As mentioned earlier in the course, accidents are processes that culminate in an injury or illness. An accident may be the result of many factors (simultaneous, interconnected, cross-linked events) that have interacted in some dynamic way. In an effective accident investigation, the investigator will conduct three levels of cause analysis:

Injury analysis. At this level of analysis, we do not attempt to determine what caused the accident, but rather we focus on trying to determine how harmful energy transfer caused the injury. Remember, the outcome of the accident process is an injury.

Event Analysis. Here you determine the surface cause(s) for the accident: Those hazardous conditions and unsafe behaviors described throughout all events that dynamically interact to produce the injury. All hazardous conditions and unsafe behaviors are clues pointing to possible system weaknesses. This level of investigation is also called "special cause" analysis because the analyst can point to a specific thing or behavior.

Systems analysis. At this level you're analyzing the root causes contributing to the accident. You can usually trace surface causes to inadequate safety policies, programs, plans, processes, or procedures. Root causes always pre-exist surface causes and may function through poor component design to allow, promote, encourage, or even require systems that result in hazardous conditions and unsafe behaviors. This level of investigation is also called "common cause" analysis (in quality terms) because you're identifying a system component that may contribute to common conditions and behaviors that exist or occur throughout the company.

I think the greatest challenge to effective accident investigation is to transition from event analysis to systems analysis. Why? Because it's hardly ever done.

One last important point to make is that most accident processes are far more complex than you might originally think. Some experts believe at least 10 or more factors come together to cause a serious injury accident. Other experts state that an average of 27 factors directly and indirectly contribute to a serious accident.

Only by thoroughly conducting all three levels of analysis can you design system improvements that effectively eliminate hazardous conditions and unsafe behaviors at all levels of the organization. The accident investigation can not serve as a proactive safety process unless system improvements effectively prevent future accidents.

Injury Analysis

If you examine the surface cause categories in 6.3 and 6.4, you will find that each condition or behavior may somehow result in the transfer of a harmful level of energy to a person's body causing injury. The severity of the injury depends on the magnitude of the harmful energy. Below are the various forms of energy that can be harmful.

Harmful forms of energy 1. ACOUSTIC ENERGY - Excessive noise and vibration. 2. CHEMICAL ENERGY - Corrosive, toxic, flammable, or reactive substances. Involves a release of energy ranging from "not violent" to "explosive" and "capable of detonation". 3. ELECTRICAL ENERGY - Low voltage (below 440 volts) and high voltage (above 440 volts). 4. KINETIC (IMPACT) ENERGY - Energy from "things in motion" and "impact," and are associated with the collision of objects in relative motion to each other. Includes impact between moving objects, moving object against a stationary object, falling objects or persons, flying objects, and flying particles. Also involves movement resulting from hazards of high pressure pneumatic, hydraulic systems. 5. MECHANICAL ENERGY - Cut, crush, bend, shear, pinch, wrap, pull, and puncture. Such hazards are associated with components that move in circular, transverse (single direction), or reciprocating motion. 6. POTENTIAL (STORED) ENERGY - Involves "stored energy." Includes objects that are under pressure, tension, or compression; or objects that attract or repulse one another. Susceptible to sudden unexpected movement. Includes gravity - potential falling objects, potential falls of persons. Includes forces transferred biomechanically to the human body during lifting. 7. RADIANT ENERGY - Relatively short wavelength energy forms within the electromagnetic spectrum. Includes infra-red, visible, microwave, ultra-violet, x-ray, and ionizing radiation. 8. THERMAL ENERGY - Excessive heat, extreme cold, sources of flame ignition, flame propagation, and heat related explosions.

Event Analysis

In the last module you learned that each event in our sequence will include descriptions of actors and their actions that may have contributed to the accident.

Our next step is to examine each event to determine:

1. the actor that represents a hazardous condition, and
2. action that represents an unsafe behavior.

The hazardous conditions (actors) and unsafe behaviors (actions) we identify as contributing to the accident are called the surface causes of the accident.

After you identify surface causes, you'll need to determine if inadequate safety system components contributed to the accident by allowing the hazardous conditions and unsafe behaviors to develop or occur. These system inadequacies are called the root causes of accidents. Let's take a closer look at these two very important concepts.

More on Event Analysis

Well, you know what surface and root causes are, and you know all about the three levels of analysis required for an effective investigation, but what techniques can you use to help conduct the analysis? Let's take a look at one technique that I have found efficient in conducting an event analysis.

I've used a "fishbone diagram" below to help you conduct an event analysis. Follow the steps below when using this tool.

1. Get a sheet of paper.
2. At the top of the sheet write "Accident Analysis". Doing this reminds you that you are breaking down the process into a number of events.
3. At the left side of the sheet, centered, write "The Injury".
4. Extend a horizontal line out from the right of the box.
5. Describe the injury event on the horizontal line.
6. Identify and circle the actors and actions described in the event statement.
7. Start asking why questions (at least five whys) about the actor and actions to uncover any hazardous conditions or unsafe behaviors.
8. Draw lines either angling up or down from the circled actors and actions and write the answers to your questions.
9. Repeat these steps with each of the new level of answers.

The diagram you produce using this procedure should look something like this. Each level of questioning will get you closer to the root cause(s) that contributed to the hazardous conditions or unsafe behaviors. Once you start identifying inadequate policies, programs, plans, processes, and procedures...you are getting to the real root causes!

Last words...

Finally, it's important to understand that most accidents in the workplace result from unsafe work behaviors. According to the latest research:

• unsafe behaviors represent the primary surface cause for about 95% of all workplace accidents;
• hazardous conditions represent the primary surface cause for only about 3% of workplace accidents; and
• uncontrollable (unknowable) causes account for the remaining 2%.

These statistics imply that management system weaknesses contribute in some way for fully 98% (conditions + behaviors) of all workplace accidents.

To effectively fulfill your responsibilities as an accident investigator, you must not close the investigation until these root causes and solutions have been identified.

Whew! That was a lot to take in. Time for the quiz!

REVIEW QUIZ

This is an open book review quiz. It's important to complete this quiz as some of the final exam questions are derived directly from the questions within this module quiz. Immediately after submitting the quiz, you will receive a web page containing your answers and the correct "book" answers.