Hazard, Risk and Controls PDF

# Hazard, Risk and Controls ## Learning Objectives: Upon completion of this module, you should be able to: - **Define**: - Define hazard, risk, energy source, probability and consequence. - Define the levels of the Hierarchy of Controls. - **Differentiate**: - Classify the elements of...

# Hazard, Risk and Controls ## Learning Objectives: Upon completion of this module, you should be able to: - **Define**: - Define hazard, risk, energy source, probability and consequence. - Define the levels of the Hierarchy of Controls. - **Differentiate**: - Classify the elements of a situation as hazards or energy sources. - Differentiate between probability and consequence. - Classify a control according to its level in the Hierarchy of Controls. - **Analyze**: - Analyze a situation to identify the energy sources and corresponding hazards. - Analyze a situation to determine the probability of occurrence and consequence of the outcome for a hazard. - Apply a Risk Matrix assessment to determine the risk for a given hazard. - Use the Hierarchy of Controls to identify the relative effectiveness of different control options. ## Topic 1: Defining Hazard, Risk and Controls ### Definitions When we use the words hazardous or risky to describe a situation or activity during casual conversation, we often mean the same thing. But in the field of risk analysis, the terms hazard and risk have specific and distinct technical meanings. A hazard is a source of potential harm while risk describes the probable size of the impact of a hazard. Fortunately, we can learn to identify hazards and understand the associated risk so that everyone can work safely. In the following sections you will learn to: - Understand hazards. - Understand risk. - Control risk to prevent harm. ## Topic 2: Hazards ### Defining a Hazard In this section, you will learn what a hazard is and how to identify one. We can easily recognise and correct some hazards that exist in the workplace, but others are more difficult to identify. In some occupations, hazards are an intrinsic part of the job and must be managed to ensure a safe workplace. Sometimes a hazard may be immediate and must be dealt with without delay to avoid a serious situation. Other times hazards are less obvious and their effect may only be felt over a period of time. A hazard can be defined as follows: - A hazard is a source of potential harm. - A hazard exists when a source of energy could be released. - For every hazard, a corresponding source of energy exists. - A loss of containment event occurs when the energy corresponding to the hazard is released in an unwanted way. ### Sources of Energy In order to prevent a loss of containment, you need to identify the hazard. To identify the hazard, look for a source of energy. There are multiple forms, or sources, of energy, and each of these can create a different hazard. The following table lists sources of energy and examples of hazards, i.e. sources of potential harm, originating from these energy sources. | Energy | Hazard | |--------------|-----------------------------------------------------------------------| | Gravity | Working at heights or unsecured objects | | Electricity | Live exposed electrical wires | | Mechanical | Moving equipment or parts | | Chemical | Toxic gasses and chemicals | | Pressure | Air or compressed gas | | Noise | Sustained or repeated exposure to loud noise | | Thermal | Sustained or repeated exposure to heat or cold | | Radiant | Intense light, ionizing radiation, thermal radiation | ## Topic 3: Risk ### Understanding Risk The terms 'hazard' and 'risk' are often used interchangeably, but when we are talking about workplace health and safety, each term has a very specific meaning. In the previous section you learned what a hazard is and how to identify a hazard based on its energy source. The next step is to understand how risk is defined. The following concepts are integral to understanding the nature of risk. We will explore each concept in detail in this section. - **Probability of occurrence** is an estimate of how often a hazard occurs, for example, 1.35 per 100,000 work hours. - **Consequence of outcome** is the size of the impact if the hazard occurs, for example, one fatality, three critical injuries, and $500,000 in additional direct costs. - **Risk** is defined as probability of occurrence x consequence of the outcome. Risk describes the probable magnitude of the impact of a hazard. Risk might be expressed: - **Qualitatively**: for example, as moderate, high, or extreme; or - **Quantitatively**: for example, as a frequency of fatalities per unit time or as an expected cost per unit time. ### Probability and Consequence - **Probablity**: In the example from topic two regarding the unsecured load, the probability of occurrence that a worker could get hurt depends on different factors, such as training. For example, two companies are responsible for loading the truck. Company A doesn't train its employees to secure loads, but Company B does. The probability of this type of accident occurring is higher for Company A because its employees don't secure loads. - **Consequence**: The consequence of the outcome is the second part of the risk equation. It describes the severity of the result, i.e. if the unwanted event occurs, how bad can the outcome be? In the case of the unsecured load, the consequence could be severe injury or death. During a hazard and risk assessment, we can assign a value such as low, medium or high, to probability of occurrence and consequence of the outcome. We can then determine the degree of risk associated with the unwanted event using the equation: $Probability \ of \ Occurrence \ x \ Consequence \ of \ the \ Outcome = Risk$ **For example:** if the Probability of Occurrence = high and the Consequence of the Outcome = high Then from the equation, the Risk of an unwanted event is High x High = High. ## Topic 4: Risk Assessment ### Methodologies In this section, you will learn how to determine the amount of risk associated with a situation by conducting a risk assessment. You will learn about a few key features of risk assessment and then work through an example risk assessment. We can assess risk in a number of different ways. We will explore one risk assessment methodology in detail, but numerous methodologies exist. Each is a method of structured problem analysis that provides a different perspective and insight into a workplace's hazards. Different fields of practice tend to prefer different methods. Each method has advantages and disadvantages. Once you are familiar with different methods to assess risk, you will develop the judgement to choose the right assessment method to apply to each specific situation. No matter which methodology you use, it is important to approach the task in a structured, logical manner. ### Qualitative and Quantitative Risk Assessments You can analyze the hazards in a situation using either a qualitative approach or a quantitative approach. - **Qualitative analysis**: In a qualitative analysis, risk is described in relative terms and categorized by level. For example, using a qualitative approach you might determine that Hazard Scenario A is a moderate risk while Hazard Scenario B is an extreme risk. - **Quantitative analysis**: In a quantitative analysis, risk is described using numbers. A quantitative analysis usually produces numerical estimates and error ranges bounding the confidence of predictions about risk. For example, using a quantitative approach you might conclude that Hazard Scenario A is a risk of 0.000001 injuries per 100,000 hours, while Hazard Scenario B is a risk of 0.001 injuries per 100,000 hours. ### Comparing Qualitative and Quantitative Analysis There are advantages and disadvantages to both qualitative and quantitative analysis. As the table below illustrates, a quantitative analysis is more detailed and more certain, but it takes more time and resources to complete. Sometimes a qualitative assessment will be carried out to identify the greatest risks and then a follow-up quantitative assessment will be done to further detail a small number of high risk scenarios. | Risk Assessment | Description | |---|---| | Qualitative Risk Assessment | Less detail, Less certain, Low cost, Less time, Suitable for most scenarios, including times when risk is well understood | | Quantitative Risk Assessment | More detail, More certain, Higher cost, More time, Suitable for high risk scenarios, when a team disagrees on risk, or a business case is needed | ### Risk Matrix One method you can use to assess risk is to use a risk matrix. A risk matrix is a simple way of rating and ranking the risks of an event. A risk matrix is created using the risk definition of probability of occurrence x consequence of the outcome. In the matrix illustrated below, the level of probability is indicated along the blue vertical axis from rare to certain. The degree of consequence is indicated along the blue horizontal axis across the top from insignificant to catastrophic. In the body of the table, degrees of risk are differentiated by colour, varying from low (green) through medium (brown), high (yellow), and extreme (red). | Probability | 1 Insignificant | 2 Minor | 3 Moderate | 4 Major | 5 Catastrophic | |---|---|---|---|---|---| | 5 Certain | HIGH | HIGH | EXTREME | EXTREME | EXTREME | | 4 Likely | MEDIUM | HIGH | HIGH | EXTREME | EXTREME | | 3 Possible | LOW | MEDIUM | HIGH | EXTREME | EXTREME | | 2 Unlikely | LOW | LOW | MEDIUM | HIGH | EXTREME | | 1 Rare | LOW | LOW | MEDIUM | MEDIUM | HIGH | ### Probability and Consequence Categories In order to use the risk matrix, you need to know what the terms for the different categories of probability and consequence mean. These terms must be formally defined so that everyone involved in the risk assessment understands the limits of each category. - **Definitions - Probability Categories**: - **Certain**: An event is likely to occur often during the life of the operation. - **Likely**: An event is likely to occur several times in the life of the operation. - **Possible**: Likely to occur sometime in the life of the operation. - **Unlikely**: Unlikely, but possible to occur. - **Rare**: So unlikely it is assumed not to occur. - **Definitions - Consequence Categories**: - **Catastrophic**: Death, loss of plant, release of material to the environment with public interest, and/or regulatory intervention occurs. - **Major**: Permanent impairment, serious loss of time due to injury, partial loss of plant, and/or lesser release of material to the environment occurs. - **Moderate**: Short loss of time due to injury, short term plant closure and/or a release to the environment of recoverable material occurs. - **Minor**: Minor injury, minor damage to plant, and/or minor confined environmental exposure occurs. - **Insignificant**: A very minor incident occurs, less significant than any of the other categories. ### Risk Matrix Example Let's do a risk matrix assessment on the example of the truck with the unsecured load that we looked at earlier in this module. To review, when the worker opened the trailer doors the load fell on the worker. The worker was critically injured and later died in hospital. In addition to this fatality, this company has had three other incidences similar to this one in the last year. Two of the incidences were near misses and no one was hurt; in the other incident, a worker's leg was broken when an unsecured box containing a heavy piece of equipment fell on the worker. In order to determine the risk associated with this company's operations, we need to evaluate probability and consequence. What do you think the probability is of another incident occurring involving an unsecured load? What is the likely consequence of such an event? ### Evaluate Probability When evaluating probability, consider the history of the company. Four accidents-two near misses, one broken leg and one fatality-have happened in the last year where an unsecured load has fallen from the back of a trailer when the door was opened. Based on this knowledge, we can conclude that an unsecured load falling from a trailer and endangering workers is likely to occur often during the lifetime of this company or operation. Therefore, the probability of an incident occurring is certain. Recall how probability is defined. ### Evaluate Consequence When evaluating consequence, review the results of the four previous incidents. While luckily no one was hurt in two of the incidents, in one incident a worker suffered a broken leg and in another incident a worker died. Since a fatality occurred as a result of one of the four incidents involving an unsecured load during the past year, the consequence of this event is catastrophic. Recall how consequence is defined. ### Evaluate Risk Now that we have determined the probability and the consequence in our unsecured load example, we can determine the risk using the risk matrix. The risk matrix helps us to visualize risk as the product of probability and consequence. Determine the risk for the unsecured load example using the matrix: - Locate the certain category along the probability axis of the risk matrix below. - Locate the catastrophic category on the consequence axis. - Draw a horizontal line from the certain category and a vertical line from the catastrophic category. Where do they intersect? In this example, probability and consequence intersect on the matrix at extreme. This means that the risk of an incident occurring involving unsecured loads at this company is extreme. The company needs to make changes immediately to ensure the safety of its workers from the hazard of unsecured loads. ### Preventative Risk Assessment The primary reason for conducting a risk assessment after an incident is to prevent further incidents, thus minimizing loss and creating a safer work environment. In the unsecured load example, if the company had completed a risk assessment after the first near-miss incident, it would have realised a risk existed and taken steps to prevent similar events from occurring. The company's corrective action may have changed the probability of another incident occurring from certain to possible. However, the consequence would still have been major or catastrophic because a heavy load falling several metres could kil or seriously injure someone. Using the risk matrix again, we can see that even with a probability of possible, the risk is still extreme. The results of the risk matrix indicate that immediate changes to the company's policy and procedures are warranted. A proactive approach to assessing risk results in a much safer work environment. ## Topic 5: Hierarchy of Controls ### Introduction to Hierarchy Controls After a risk assessment is complete, we can use our findings to determine which risks are greatest then develop controls to reduce these risks. A control is a feature that reduces risk by preventing a hazard from being exposed to the surroundings or minimizing the impact of the exposure. Some controls are more efficient while others require more effort to implement. One way to think about types of controls is the Hierarchy of Controls. In the hierarchy, different categories of controls are ordered from most effective to least effective. The most effective controls are often the most expensive. As you become more experienced in your career, you will develop your engineering judgement to select the appropriate controls for a given hazard and risk level. ### Hierarchy of Controls The hierarchy of controls lists general measures that can be taken to reduce risk. The measures are arranged in order of effectiveness. Elimination is the most effective approach to risk reduction, so it sits at the top of the hierarchy. Elimination is followed in order of decreasing effectiveness by inherent safety, engineered safety controls, administrative controls and, lastly, personal protective equipment. ### Elimination and Inherent Safety Lets explore each of the measures to reduce risk in the hierarchy of controls in more detail from most effective to least effective. - **Elimination**: Elimination is the most effective way to control hazards. If the hazard no longer exists, then the risk no longer exists. Eliminating a hazard ensures everyone and everything is safer. Let's return to our earlier example of the unsecured load. Recall that in this example, workers loaded a trailer with heavy boxes of supplies but failed to secure the load. During transport, the load shifted. When a worker opened the truck door, the load fell on the worker and the worker was killed. Did the load of supplies have to be moved? If not, then the hazard might have been eliminated, i.e. the truck does not contain heavy boxes of supplies. - **Inherent Safety**: Often, we cannot completely eliminate a hazard, but it is a good first questions to ask ourselves when exploring control options. If a hazard cannot be eliminated, it may be possible to change the design of the process to make it inherently safer. An inherently safer design is one that permanently eliminates or reduces hazards to avoid or reduce the consequences of incidents. A process can be made inherently safer using one of four inherently safer design principles: - **Minimization**: Minimization means reducing the amount of a hazard that is present. In the example of the unsecured load, could the load have been packaged in several smaller containers to minimize the gravitational energy released by the movement of individual items in the load? Should the items fall, they would have less impact and the risk of the hazard would be reduced. - **Substitution**: Substitution means replacing a hazard with a lesser hazard. In the example of the unsecured load, could a load with a lower mass have been transported instead of the load with the high mass? A lower mass load would pose less of a hazard to workers unloading the truck. - **Moderation**: Moderation means using a less hazardous form of a hazard. In the example of the unsecured load, could buffering material have been packed around the load so it would not be able to shift enough to fall? An example of moderation involving chemical processes is diluting a hazardous chemical to a less hazardous concentration to reduce the risk of acid burns. Another example is carrying out a hot process at a lower temperature to reduce the risk of thermal burns. - **Simplification**: Simplification means operating around a hazard in as easy and direct a manner as possible, thus minimizing the probability of errors. Securing the load in the example of unsecured load would have significantly reduced the risk of an incident. Suppose there are two options for restraining systems, one that can be applied by a single operator with a single step and one that takes two operators and a dozen steps. It may be preferable to use the single operator restraining system because it is simpler and there is less likelihood of it being applied incorrectly. ### Engineering Controls Engineering controls are systems added on to a process in order to prevent or mitigate a loss of containment. Remember that a loss of containment event occurs when the energy corresponding to the hazard is released in an unwanted way (see topic 2). Adding engineering controls to a process is a less effective method of reducing risk than using inherently safe design. Even so, engineering controls can still intervene to prevent loss of containment of a hazard Examples of engineering controls include the following: - A strap that can be anchored to secure a load. The strap does not impact the transport of the load unless the load begins to shift, then the strap will prevent movement. - A temperature sensor that monitors a chemical process. The sensor does not interfere with the process, but if the temperature rises above a critical threshold, it can trigger rapid cooling to prevent a runaway reaction. Note that even though these controls are referred to as 'engineering,' this does not mean that engineering concepts are applied only to this level of the hierarchy. Engineers can contribute to all levels of the hierarchy of controls. ### Administrative Controls Administrative controls are controls that reduce risk by instructing how work must be done safely. They include activities such as training, as well as written rules and procedures that instruct personnel how to act when around hazards. Unfortunately, administrative controls can be ignored and thus fail to provide the intended protection. Examples of administrative controls include the following: - Instructing workers about the dangers of unsecured loads and how to properly secure them. - Labelling hazardous goods that are being stored or transported using a system such as WHMIS (Workplace Hazardous Materials Information System). - Providing step-by-step instructions on how to start, operate, and stop a piece of equipment. - Mandating site assessments and work permits before welding is undertaken. ### Personal Protective Equipment Personal protective equipment (PPE) is equipment that a worker wears to protect themselves from hazards. It is the final item on the hierarchy of controls which means it is the least effective control. - **Limitations of PPE**: - As a barrier against exposure to a hazard, PPE is physically very close to the worker. For example, a lab coat is close to the wearer's skin. - PPE may stop protecting the worker with little or no warning. For example, a glove with a tear or a malfunctioning respirator no longer protects the wearer. - The worker may wear the equipment incorrectly or choose not to wear it at all. For these reasons, PPE should always be considered a last line of defense and should be supplemented by other controls that are higher on the hierarchy of controls. - **Examples of PPE**: - Safety boots and hard hats to distribute impact energy. - Reflective vests that make personnel highly visible thus reducing the probability of impacts. - Ear plugs to reduce the intensity of loud noise. - Insulated gloves to protect from temperature extremes. - Face shields and coveralls to protect skin against hazardous materials. - Dust masks to reduce the inhalation of fine particles. - A fall arrest harness to stop a worker's fall from a height. ### Multiple Controls In order to effectively reduce risk when undertaking an activity or planning process, you can use controls from each level of the hierarchy as well as the inherently safer design principles. Consider the following example of an engineering student mixing cement with water as an assignment in a laboratory. As you can see from the table, the risk level for the student is minimized through a variety of controls across different levels of the hierarchy of controls. | Control | Type of Control | |---|---| | The student wears safety boots, coveralls, gloves, a dust mask, safety glasses and a hard hat. | PPE | | The laboratory supervisor has given the student training on how to properly use this PPE, and has a policy that the PPE must be worn at all times in the lab. The student is following detailed instructions for the order and expected duration of tasks. | Administrative | | The laboratory is well ventilated to remove dust. | Engineering | | The student is not pressed for time and does not have to multitask. The student has plenty of time to focus on slowly mixing the cement and water thus reducing the amount of cement dust | Minimization and simplification inherently safer design principles | ## Module Summary You have reached the end of this module. You should now be able to: - **Define**: - Define hazard, risk, energy source, probability and consequence. - Define the levels of the Hierarchy of Controls. - **Differentiate**: - Classify the elements of a situation as hazards or energy sources. - Differentiate between probability and consequence. - Classify a control according to its level in the Hierarchy of Controls. - **Analyze**: - Analyze a situation to identify hazards by first looking at energy sources. - Analyze a situation to determine the probability of occurrence and consequence of the outcome for a hazard, and identify the risk as a product of probability and consequence. - Apply a Risk Matrix assessment to determine the risk for a given hazard. - Use the Hierarchy of Controls to identify the relative effectiveness of different control options. Throughout this module, you applied the concepts you learned to the recurring example of an unsecured load. Given your new understanding of hazard, risk and control, the next time you have to move furniture what will you do differently? How will your approach to this task change? You can review the course content anytime by accessing the course menu. If you are ready to take the module exam, click the 'Complete' button below to close this module and access the exam.