In this article, Certified Industrial Hygienist and Workplace Safety Expert, Ron Schaible provides an overview of risk assessment and hazard analysis.
The workplace safety experts at Robson Forensic are retained to investigate a broad range of workplace injuries covering industrial, commercial, and transportation facilities.
The world is a dangerous place in which to live despite advances in science, engineering and medicine. New risks associated with materials, processes and products need to be properly anticipated, recognized, evaluated and controlled. Methods exist to proactively anticipate, recognize, evaluate and control hazards.
WHAT IS RISK?
A discussion of risk is best prefaced with a few useful definitions1:
- Harm: Physical injury or damage to health of people. Note: This may be a result of direct interaction with a hazard such as a machine, or indirectly as a result of damage to property or to the environment.
- Hazard: A potential source of harm.
- Protective measures: Design, safeguards and complementary protective devices, administrative controls, warnings, work procedures, training or personal protective equipment used to eliminate hazards or reduce risks.
- Residual risk: Risk remaining after protective measures have been taken.
- Risk: A combination of the probability of the occurrence of harm and the severity of that harm.
- Risk assessment: The process by which the intended use of the machine, tasks and hazards, and the level of risk are determined.
- Tolerable risk: Risk that is accepted for a given task and hazard combination [hazardous situation].
Within the context of workplace safety and health, occurrences of harm stem from hazard exposure experienced in the workplace, as well as the ambient environment. These exposures include inhalation of or contact with hazardous chemicals, unguarded machinery, fire and explosion situations, and environmental pollutants. Therefore, a more comprehensive definition of risk could be “the measure of the probability that exposure to a hazard will result in a negative consequence.” Risks are acceptable if they are judged to be tolerable (“acceptable risk”). Minimum risk is achieved when all risks deriving from hazards are at a realistic minimum. Minimum risk does not mean zero risk, which may not be attainable. Safety is defined as that state for which the risks are judged to be acceptable.
RISK ASSESSMENT DECISION MATRIX
There is a framework that uses hazard categories as a starting point for evaluating risk. This framework can be used in any situation where death, system loss, or property, equipment or environmental damage is a concern. These categories require understanding the particular product or process being evaluated, and what the terms mean to an individual operation. Consider the following definitions of categories of hazard severity suggested by Manuele:
Next, one must establish criteria for defining hazard probability. The word “probability” implies a quantitative determination of likelihood. Unlike the chemical process industry, where published statistical failure data based on historical operational data and research data is available, many times quantitative probabilities are not available. Typically, a consensus of subjective, professional opinions of knowledgeable persons is used. Consider the following qualitative definitions of hazard probability rankings suggested by Manuele:
Using the above definitions helps establish a matrix to develop qualitative assessments of risk to establish priorities.
If risk analyses and hazard assessments are performed, those responsible for conducting analyses and assessments must be skilled in the proper use of the special analytical techniques that are available. There are over 25 hazard analysis techniques and each has its advantages and limitations. The techniques most applicable to the chemical process industry are discussed in OSHA’s Process Safety Management regulation, 29 CFR 1910.119. The most common assessment and analysis methodologies include Checklists, Fault Tree, What IF Technique, Hazard and Operability Study (HAZOP), Failure Modes and Effect Analysis (FMEA), and Management Oversight and Risk Tree (MORT).
Hazard control flows from the assessments of risk and hazard analyses. A logical thought process has been developed and available since at least the early 1960s to guide the achievement of controlling hazards. This thought process is known as the “Safety Hierarchy”2 and presents basic measures for preventing accidental injury in order of effectiveness and priority preference. The measures are:
- Eliminate the hazard from the machine, method, material, or plant structure.
- Substitute or replace the hazard with the least hazardous alternative.
- Control the hazard by enclosing or guarding it at its source.
- Train or warn personnel to be aware of the hazard and to follow safe job procedures to avoid it.
- Prescribe personal protective equipment for personnel to shield them against the hazard.
Eliminating the hazard through design is preferred because there is no residual hazard requiring further action.
Design changes and guards are the next but lower level of protection. A residual hazard remains, either by the design of the guard itself (which is an inherent design defect) or by the actions of the worker to properly and regularly use or maintain the guard.
Safety, health, and environmental training is an important element of an effective overall safety, health, and environmental program. Historically, safety, health, and environmental training has been specifically addressed by only a few regulations with limited scope, such as asbestos, hazard communication, and storm water management. The regulations usually only specify the technical issues to be covered in a training course. But training that is not competently developed, delivered, and measured for effectiveness can be disregarded, or forgotten due to stress or other stimuli. A recent consensus standard on effective safety and health training3 provides accepted guidelines to adequately design, develop, deliver, and evaluate training. The standard is applicable to a broad range of training and training programs. The goal of risk communication is to provide information to workers so that they may make informed – and hopefully, the correct - choices.
Personal protective equipment is the lowest form of safeguard. Its use is an acknowledgement that the hazard continues to exist at a level that constitutes a sufficient injury potential. Unfortunately, employers frequently resort to the use of personal protective equipment as the sole remedy for a hazard. Sometimes personal protective equipment is relied on until an engineering control is developed and implemented. However, the engineering control often gets delayed or forgotten due to the lapse of time, budget constraints, or other competing priorities and the personal protective equipment is the workers’ sole line of defense against the persistent hazard. Failures involving personal protective equipment include: improper equipment selection for the hazard, workers not knowing when to wear specific equipment, and not knowing how to properly maintain the equipment.
Traditional hazard analysis has long advocated the identification and evaluation of all hazards. The risk reduction process is not completed until tolerable risk is achieved. The process described in this article summarizes an established method to proactively recognize risks associated with tasks so that safety related designs and modifications are made while providing for improved productivity and maintainability.
OCCUPATIONAL AND INDUSTRIAL SAFETY
The industrial safety experts at Robson Forensic have designed, built, maintained, and operated industrial machines and equipment. Our experts are well versed in federal OSHA regulations, state OSHA plan requirements, industry consensus standards, guidelines, and best practices affecting workplace safety.
For more information submit an inquiry or contact the author of this article.
Certified Industrial Hygienist
Ron Schaible is an Industrial Hygienist, Workplace Safety & Ergonomics Expert at Robson Forensic, Inc., a forensic engineering consulting firm headquartered in Lancaster, PA. Ron has over 40 years of health, safety, ergonomics/human factors, indoor air quality, and environmental experience. He is a Certified Industrial Hygienist, Certified Safety Professional, Certified Human Factors Professional/Ergonomist, and a Registered Professional Engineer #36714-Safety (Massachusetts).
- Association for Manufacturing Technology (November 2000). “ANSI B11 TR3-2000, Risk Assessment and Risk Reduction - A Guide to Estimate, Evaluate and Reduce Risks Associated with Machine Tools”. McLean, VA.
- McElroy, Frank E., Editor. (1964). Accident Prevention Manual for Industrial Operations, 5th Edition. National Safety Council, Chicago, IL. 4-1.
- ANSI Z490.1-2001, “Criteria for Accepted Practices in Safety, Health and Environmental Training”. American National Standards Institute, New York.