Chapter 1: Introduction to Risk Assessment and Control, Accident Analysis PDF

Chapter 1: Introduction to Risk Assessment and Control, Accident Analysis Objectives The first objective of this chapter is to ensure that students understand the fundamental concepts related to workplace safety, such as the difference between a hazard and a risk. More...

Chapter 1: Introduction to Risk Assessment and Control, Accident Analysis Objectives The first objective of this chapter is to ensure that students understand the fundamental concepts related to workplace safety, such as the difference between a hazard and a risk. Moreover, students should be able to identify the stakeholders and actors involved in the prevention of occupational risks. The second objective aims to familiarize students with the different indicators used to measure workplace accidents, such as the frequency rate and the severity rate. Occupational diseases and the methods to evaluate them can also be included in this objective. Students should be able to observe and analyze the specific risks associated with a given work situation. This could involve identifying potential hazards, assessing the associated risks, and understanding methods to mitigate these risks. The objective here is to develop in students the ability to create a cause tree in the event of an accident. This involves analyzing the contributing factors to an incident, organizing them hierarchically, and understanding the cause-and-effect relationships. These objectives aim to provide students with a thorough understanding of the basic principles of risk assessment and control in the workplace, as well as practical skills to identify, evaluate, and prevent potential hazards. Introduction Occupational hygiene is the discipline that deals with the professional environment to ensure it is optimal for the health and well-being of workers. It is integrated into the vast field of occupational health, complementing occupational medicine, ergonomics, and safety. Hygiene, Health, and Safety at Work now hold an increasingly dominant place in the company's strategy and management, because beyond the human and social tragedy caused by a workplace accident (WA) or an occupational disease (OD), the economic and legal impacts are often significant. It is important to note that the field of Occupational Health is situated, in our society, at the interface of vast and very important areas that concern our health and general well- being (public health), our environment (ecology and sustainable development), and our economy. (company). This means that there are interactions between these various fields and Occupational Health, which must be taken into account when one wants to act and organize the prevention and improvement of working conditions. The climate allows our survival and biodiversity is a potential reservoir of medicines. From climate change on a global scale to more localized pollution, respect for the environment has become a major concern for our society. The sources of contamination are numerous, including those related to human activities (industries, improper treatment of wastewater, household waste, etc.), to which are added sources of natural pollution. The first chapter is dedicated to safety, hygiene, and occupational risks. It mainly addresses the general aspects of health and safety at work and some issues included in the occupational health plan. The recognition of the complexity of environmental phenomena and their links with human activities is the subject of the second chapter. Sustainable development, which is now being used to improve the living conditions of all the world's citizens, will also be presented there. 1.1 Understand the basic concepts (hazard, risk) and identify the actors of prevention 1.1.1. Definitions At the origin of every accident, even minor ones, there is a risk or danger that, under certain conditions, leads to accidents. In this paragraph, the concepts of risk, danger, and risk factors are presented. We attempt, by presenting them in parallel, to weave a reflection on what brings them together more than what sets them apart. In their common usage or depending on the fields of application, danger, risk, and hazard completely or partially overlap. The accident is defined as an unforeseen and sudden event that has caused bodily and material damage. The damage caused can be more or less significant, either temporary or permanent. A. Danger Refers to a material situation involving the potential for harm to the physical integrity of individuals, damage to property or the environment, or a combination of these harms. The hazard represents a potential threat of harm, while the risk is an assessment of exposure to that hazard. (see the figures below). The hazard is therefore a "cause capable of causing harm." (on a target or an issue). "The danger is the instrument of the risk" B. The risk The risk, a trap word where danger and consequence are both confused, is the combination of the probability of a malfunction occurring and its potential severity. The risk measures the level of danger. The risk is the probability that potential harm occurs under conditions of use and/or exposure and the possible extent of the harm. "The hazard is a condition, the risk its measure." Risk factors are elements that can increase or decrease the likelihood of an accident occurring or the severity of an event. Risk factors complement The equation: Risk = Hazard * Exposure In the present context, when we talk about exposure, it refers to the contact between the hazard and a person, which can then lead to harm. Without exposure, there is no possibility of harm. The risk is therefore the probability that someone will be affected by a hazard. In summary, at the origin of every accident, there is one or more risks or dangers, and when numerous parameters are combined, the risk gives rise to an accident. A source of risk is generally characterized by: By the presence of one or more potential hazards, that is, a situation bringing together all the factors that could lead to a potential accident or cause an undesirable event and compromise the safety of people, the security of installations, and the environment: o hazardous products: flammable, explosive, toxic, polluting o dangerous chemical reactions: incompatibility, corrosion, thermal runaway, release of toxic products,... Fire-explosion risks PRODUCTS o Explosives o Oxidizers o Extremely Flammable o Easily Flammable o Flammable Risk of poisoning o Very toxic o Toxic o Harmful o Corrosive o Irritant o Sensitizing o Carcinogenic o Asphyxiant o Dangerous for the environment Operating conditions: pressure, temperature, electricity, radiation, energy, noise, heat/cold. PROCESSES/MATERIALS o Continuous, Discontinuous o Pressure, Vacuum o Temperature o Machines o Electricity o Start/Stop o Work WORK ENVIRONMENT o Noise - Agitation o Dust o Heat/Cold/Weather Conditions o Radiation o Design/Layout o Clutter o Isolation C. Damage A damage is an injury (accidente) or a harm to health. (disease). Consequences of an event on the goods, people, and functions of a system. (The damages can be expressed in human, financial, economic, social, or environmental terms.) Examples: fracture, occupational disease, poisoning, deafness, death. In a company, danger can manifest as a wet board, a live electrical wire, a stepladder, a lift platform, a steamroller, etc. So: Bumping your head, getting electrocuted, falling, severing a limb, etc. are consequences (damage) that result from being in the presence of a hazard. The risk is the possibility of damage occurring as a result of exposure to a hazard. Example: risk of finger crushing by the hammer Danger - Risk How can sharks help us differentiate between the concepts of danger and risk? Shark = danger! That, everyone understands. Presence of a shark = risk There is a risk when someone is in the presence of danger. D. Notion of exposure The risk results from exposure to a hazard: Risk = Hazard X Exposure Figure (1.1), the risk of an accident occurring (human damage) is low or none because no worker is present at the hazard site (probability of plant fall), this situation represents the notion of 'no exposure' and therefore no risk. Figure 1.1: Diagram representing the "No Risk" situation Figure (1.2), the risk of an accident (human injury) occurring is very high due to the high probability of workers being present at the site of danger (probability of plant fall). This situation represents the concept of 'Dangerous situation and exposure concept'.  Figure 1.2: Representation of a dangerous situation E. Risk-based approach Figure 1.3: The Risk-Based Approach 1.2. Basic Concepts A) Nuisance: A set of elements that harm the quality of life (pollution, noise, etc.). B) Incident: It is an unwanted event that occurred during work without causing bodily injury. C) Near miss: An unexpected and sudden event that could have, under slightly different conditions, caused an accident. Dangerous circumstances: no injuries among the staff, but material damage - warnings of upcoming events. D) Work accident: A work accident can be defined as a bodily injury with temporary or permanent lesions, caused by a sudden and rapid external action. Depending on the severity of the injuries, the following are distinguished: Accidents without stoppage, minor, often without consequences, and which can be treated on-site. Accidents with a stoppage (from a few days to a few months) with injuries requiring special care. Accidents with permanent incapacity (PI) corresponding to definitive injuries and sequelae, likely to reduce work capacity (partial or total incapacity) Fatal accidents with immediate death or coma followed by death. Figure 1.4: Diagram illustrating the difference between incident, accident, and near-acident  Figure 1.5 : Classification des accidents 1.3. Risk Classification Risks can be classified according to whether they are: Mechanical: impacts from moving parts of machines, crushing from falling objects or vehicles, cuts and punctures from work tools, projections of solid particles (metal, wood, rock chips) or incandescent material, postural and visual constraints, and repetitive motions... Physical: vibrations produced by machinery, excessively high noise levels, excessively high or low temperatures, inclement weather for outdoor work (humidity, wind...), lighting levels, air quality at the workplace (dust...), electric current, fire and explosion... Chemical: exposure to chemical substances through inhalation, ingestion, or skin contact, gaseous, liquid, or solid products, carcinogenic, mutagenic, toxic, corrosive, irritant, allergenic… Biological: exposure to infectious agents (bacterial, parasitic, viral, fungal) and allergens through bites, stings, inhalation, cutaneous-mucosal routes... Radiological: presence of ionizing radiation and radioelements, laser radiation, UV and IR radiation, various electromagnetic radiations... Psychological: physical or verbal assault in the workplace by a client/student/patient, moral or sexual harassment by a superior, managerial stress, excessive mental burdens (permanent screen work, etc.) 1.4. Occupational Risks Due to the evolution of technology, the structure of jobs, and the modes of work organization, current work situations are likely to expose workers to various risks. Different classifications of these risks can be proposed according to the criteria chosen. In terms of forensic medical compensation, the term "occupational risks" refers to three types of events defined by the Social Security Code: workplace accidents, commuting accidents, and occupational diseases. With reference to the damage, that is to say, the harmful effects on health, it may involve physical injuries, illnesses, psychosocial problems, or even issues of discomfort at work. The classification according to the nature of the risk presents an obvious interest for its identification and the application of preventive measures. Occupational risks are the cause of workplace accidents and occupational diseases. Among occupational diseases, it is necessary to distinguish: - Occupational diseases are health impairments resulting from the absorption of small quantities of hazardous substances over a more or less prolonged period, to which the victim has been exposed during the performance of their duties. - Professional pathologies are health impairments resulting from the absorption of small quantities of dangerous substances over a more or less prolonged period, to which the victim has been exposed during the performance of their duties. - Among the occupational diseases, examples include: Among occupational diseases, examples include: o Occupational deafness (exposure to high noise levels). o Anemia, leukemias, contact caused by ionizing radiation (X-ray, gamma ray…). o Lead poisoning at work, … 1.5 The different types of risk 1.5.1. Mechanical risk Mechanical risk is the risk associated with human or technical failure during the use of a fixed or mobile machine or work equipment. Texts define the principles of designing safe machines and the periodic checks necessary to maintain their safe operation. Mechanical risk concerns all workers operating machinery: farmers, workers and technicians, repair and maintenance agents. 1.5.2. The noise 1.5.2.1. Rumors A sound is an acoustic vibration, that is, a movement of particles in a medium (air, for example) capable of evoking an auditory sensation. A sound becomes noise when the auditory sensation becomes unpleasant or bothersome. 1.5.2.2. The auditory effects We distinguish three: deafness, auditory fatigue, and the masking effect. Deafness is a permanent hearing impairment caused by prolonged exposure to noise. It is the auditory cells, located in the cochlea, that are irreversibly destroyed by the effect of noise. Auditory fatigue is characterized by a set of temporary disturbances resulting from exposure to noise. The main disturbance is a hearing deficit that disappears after a period of rest. The masking effect is the phenomenon by which a useful sound, such as speech, is no longer perceived due to the simultaneous presence of a masking noise. 1.5.2.3. Individual protection It is achieved by wearing earplugs or headphones. CLASSIC CORKS HELMETS Mussels Corks Figure 1.6: Individual Protection 1.5.3 Vibration-related risk It is a risk of osteoarticular, neurological, or vascular lesions resulting from the use of pneumatic tools or the operation of vehicles or machinery. Examples: Pneumatic hand tools (pneumatic hammer, chisel, impact wrenches,...) Driving vehicles (heavy trucks, public transport) or construction machinery (backhoe, compactor, bulldozer…) 1.5.4. Risk related to thermal environments It is a source of discomfort, which can lead to a decrease in alertness or precision of movements, increasing the risk of accidents and potentially leading to heat stroke or sometimes fatal hypothermia. Examples: o Work in a cold, humid environment (cold room, freezers,...) exacerbated by reduced mobility; o Work in hot environments (glassworks, rolling mills, foundries...) exacerbated by physical exertion; o Isolated work in extreme environments. Indeed, poor thermal conditions in the workplace can be the cause of headaches, respiratory discomfort, colds, and pain. 1.5.5. Danger related to handling and physical activity Poorly executed movements or inappropriate postures can cause muscular or joint disorders. For example, picking up an object from the ground is too often done with a rounded back and straight legs, putting the vertebrae in a bad position. Whereas, if you squat, your back remains straight and the intervertebral discs stay in place. Figure 1.7: (a) Bad postures and (b) good postures Generally speaking, difficult loads should be mechanized and the use of hand trucks and handling carts should be encouraged. It is necessary to adopt a good posture to lift loads, no matter how light they may be. 1.5.6. Fire risk The fire is a combustion that generally develops in a disordered and uncontrolled manner. Fires can have several origins: Human causes: electricity, flammable products, cigarettes, negligence, ignorance, malice (attacks, arson) Natural causes: lightning, sun, fermentation Energy causes: short circuit, chemical reactions, sparks, friction How does a fire start? Fire is a chemical reaction for which three elements are necessary: a material Combustible, oxygen, and an ignition temperature. This ignition temperature can be reached in the presence of a flame, a spark, a heat source, or friction... These three elements are generally presented in a triangle (Figure 1.7), called the fire triangle. The declaration of a fire is therefore the result of the coexistence of three conditions: 1. presence of a fuel 2. presence of an oxidizer (oxygen) 3. presence of a heat source Figure 1.8: Fire Triangle Conduct to follow in case of fire - Not to expose oneself unnecessarily - Control the fire if possible (if the fire is not too large) - Leave the premises by closing the door - Cut off the fluids if possible - Sound the alarm and evacuate - Identify possible evacuation routes Behavior to adopt in case of an accident In the face of an accident, I remain calm. Important: I act in the following order: 1. Protect = I protect the victim without putting myself in danger (only move the victim in case of extreme necessity and immediate danger). 2. Alert = I call for help (see emergency numbers). 3. Rescue = I let the workplace first aiders act who have been trained to perform the initial emergency actions. 1.6. Chemical risk We all use chemicals, whether in professional or domestic activities. There are currently more than 100,000 pure substances on the market, which, when mixed, yield millions of preparations. Chemicals are useful, even indispensable, because they are active. But because they are active, some can be dangerous to health. The consequences of chemical risk The possible consequences on human health at work, during the implementation of chemicals, can be of two natures: workplace accidents occupational diseases. 1.7. The work accident It can occur in all types of industries during the use of chemical substances or products containing them, particularly during manufacturing work, maintenance operations, handling, and transfer activities. It reveals itself suddenly and brutally and is expressed as: a fire an explosion burns asphyxiations acute intoxications dangerous reactions 1.8. Occupational disease Occupational Disease occurs gradually due to more or less prolonged exposure to hazardous products during the usual practice of the profession. These diseases are very diverse and can cause health impairments, some of which, very serious, can result in death. Most often, these diseases appear after multiple, repeated exposures to low doses of the product: this is chronic poisoning. Sometimes they can even appear several months, or even several years, after the operator's exposure to the product in question has ceased. In the case of cancers, this latency period can be very long (10 years or more). Table listing, non-exhaustively, various diseases associated with common products 1.9. Routes of entry into the body A. Penetration by the mouth Of course, chemicals are not ingested voluntarily. Most often, the entry through the digestive tract (or ingestion) occurs accidentally or through carelessness. B. Skin penetration It is the percutaneous route: irritants and corrosives act locally, but other fat-soluble products cross the skin barrier and disperse throughout the body, where they cause various disorders (benzene, for example). C. Penetration through the lungs It is the most frequent route of entry in the workplace because pollutants can be intimately mixed with the air we breathe. This is the case when handling solvents, glues, paints, etc. Once inhaled, these products are carried by the blood and can cause respiratory disorders but can also affect other organs. Knowing the risks Once they have deciphered the labels, users often find themselves perplexed because they do not always understand what the products in question can trigger. These products can be dangerous as they can harm health. According to their characteristics, the way they enter the body, and the amount absorbed, these products can more or less seriously affect health. Some products act like poisons spreading throughout the body via the blood. This poisoning can be severe: it is acute intoxication. It can be fatal. It can occur when used in poorly ventilated areas (cellars, silos, pits). If the exposure occurs over long periods or is repeated: it is chronic poisoning. It should be noted that the effects of this poisoning do not always disappear with the cessation of exposure. These products are classified as toxic or harmful and can cause deep damage to the body. Among these products, some are carcinogenic, meaning they can cause cancer or increase its frequency. Some are mutagenic, meaning they can cause genetic mutations that may lead to cancer. Those that can cause malformations in the embryo are teratogenic. There are two categories of products whose effects are local, limited to the area of contact with the body. - Corrosive products: They exert a destructive action on living tissues. They burn the skin and mucous membranes and can cause sometimes very serious injuries. - Irritant products: they cause itching, redness, or inflammation of the respiratory tract. - Sensitizing or allergenic products: they only cause reactions in certain individuals. 1.10. Prevention Sources of information on chemical products Hazardous chemicals must be easily identifiable. The information about these products allows users to be informed about: their choice the risks associated with their use the organization of prevention the storage and transportation conditions … waste management … Permissible limit values To limit the effect of hazardous products and not compromise the health of workers, limit values have been set. Occupational Exposure Limit (OEL) A permissible exposure limit (PEL) corresponds to the maximum concentration of a substance in the workplace atmosphere that a worker can breathe for a specified period of time without risk of health impairment. The OELs thus aim to protect workers (as well as their descendants) from the harmful health effects of exposure to one or more hazardous chemical agents. In cases where multiple pollutants are present and there is scientific evidence establishing that their effects on the organism are independent, they should be considered separately. Otherwise, particularly in the case of simultaneous exposure to solvent vapors, a conventional formula for summing individual concentrations relative to the corresponding LV can be used: C: atmospheric concentration, VL: corresponding limit value. If the sum is > 1, the limit value of the mixture of the n substances is exceeded. Recognizing hazardous materials (Chemical labeling) To help with risk prevention, pictograms for health and safety signage and chemical labeling have been defined. These pictograms, or graphic symbols, can be used to describe a situation, prescribe a specific behavior, or indicate a hazard. In the workplace, a pictogram applied to a sign contributes to health and safety signaling. Pictograms are also used for labeling chemical products (Figure 1.9). Figure 1.9: Risk Identification Pictograms The combination on the labels of these danger symbols and these R risk phrases allows for the definition of 15 categories of danger for hazardous substances and preparations: Explosives Combustibles Extremely flammable Easily flammable Inflammables Very toxic Toxic Noxious Corrosivos Irritants Sensitizers Carcinogens Mutagens Respiratory toxins Dangerous for the environment B. Emergency Procedure 1 Report the emergency situation In case of an emergency requiring the evacuation of the premises, the evacuation order is given by an audible signal "alarm signal" by the security officer of the premises to be evacuated and by their deputy. 2 Implement the evacuation plan The evacuation must be clearly explained by the person in charge so that all staff can evacuate the premises in a matter of moments: 3 minutes is a normal time frame. The evacuation plans are posted on each floor of the headquarters building and, if necessary, at the construction site. 3 Order and organize the evacuation The organization of the evacuation is ensured in accordance with the evacuation plan. The safety instructions, mainly posted in accessible and frequently visited areas by all employees and on information boards, provide guidance on the conduct to follow on-site and the phone numbers of the people and organizations to contact. The evacuation plans indicate using the signals provided for this purpose. 4 Notify external organizations 5 Check if the premises are completely evacuated 6 the families of the victims The families of the victims are informed by the human resources manager or their representative. 7 Organization of the alert Adequate alarm systems (e.g., telephone) must be available in sufficient numbers - The list of emergency phone numbers: police, civil protection, must be shown on the evacuation plan - The list of people to be notified in case of an emergency must also be displayed. 8 First Aid Provide individuals capable of providing assistance and ready to intervene during their working hours - Written instructions for first aid must be posted near alarm systems - First aid equipment and first aid kits must be installed and regularly checked 9 Evacuation of an injured person. 10 Lifting Its purpose, at the accident site, is to place the victim on a stretcher (standard or improvised). 11 Stretcher Bearer It is limited to bringing the injured person from the pickup point to the evacuation vehicle. 12 Specific Requirements During the implementation of the evacuation process, it is the responsibility of the designated safety officer to ensure compliance with HSE regulations related to: - To traffic - To fires - To wearing PPE when possible C. General Principles of Prevention To implement a prevention approach, it is necessary to rely on the nine major general principles that govern the organization of prevention. 1. Avoiding risks means eliminating the danger or exposure to danger. 2. Evaluating risks means assessing exposure to danger and the significance of the risk in order to prioritize the preventive actions to be taken. 3. Combatting risks at the source means integrating prevention as early as possible, particularly from the design of workplaces, equipment, or operating procedures. 4. Adapt the work to the individual, taking into account inter-individual differences, in order to reduce the effects of work on health. 5. Taking into account the evolution of technology means adapting prevention to technical and organizational developments. 6. Replacing what is dangerous with what is less so means avoiding the use of dangerous processes or products when the same result can be achieved with a method that presents fewer hazards. 7. Plan prevention by integrating technique, organization and working conditions, social relations, and environment. 8. Prioritize collective protective measures and only use personal protective equipment as a supplement to collective protections if they prove to be insufficient. 9. Giving appropriate instructions to employees means training and informing them so that they are aware of the risks and preventive measures. 1.11. Identification of prevention stakeholders: A) The actors of prevention within the company: The employer: The employer must take all necessary measures to ensure the safety and protect the health of the establishment's workers, including temporary workers, based on an assessment of the existing risks in their company. He personally ensures compliance with the legal and regulatory provisions that engage his responsibility. In order to fulfill his obligations, he must surround himself with all the necessary technical expertise and obtain all the required advice. The workers: Each worker must take care of their own health and safety as well as that of other people affected by their actions or omissions at work, in accordance with the employer's instructions, based on their training and within their capabilities. The Health, Safety, and Working Conditions Committee (HSWCC): This representative body of employees brings together the employer and delegates representing the employees. It is a body specialized in the prevention of occupational risks. The The CHSCT is not only involved in risk assessment and seeking solutions to improve working conditions, but it also makes proposals to the employer. The CHSCT becomes mandatory in all establishments with at least 50 employees. The employee representatives: In establishments without a Hygiene, Safety, and Working Conditions Committee (in principle, establishments with 10 to 50 employees), the staff representatives exercise all the competencies of this committee. B) The actors of prevention outside the workplace Outside the company, many other actors participate in the system of occupational risk prevention and the improvement of working conditions. In Algeria, the prevention of occupational risks is placed under the responsibility of: Ministry of Labor, Employment, and Social Security Takes care of: The development of the national policy for the prevention of occupational risks. The preparation and initiation of legislative and regulatory texts The evaluation and control of the implementation of occupational risk prevention programs. This ministry is assisted by an advisory body which is the: National Council for Hygiene, Safety, and Occupational Medicine : It is a tripartite component (employer representatives, worker representatives, public authorities). It participates through recommendations and opinions in the implementation of programs related to the prevention of occupational risks. The Central Structures of the Ministry of Labor, Employment, and Social Security are: Directorate of Labor Relations: It is responsible for the coordination, monitoring, and evaluation of P.R.P programs, the facilitation of prevention organizations, and the drafting of legislative and regulatory texts. The National Fund for Social Security for Wage Earners : It supports the DGSS (General Directorate of Social Security) which regulates the pricing and modalities for compensating work accidents and occupational diseases. It participates in the development of the prevention policy. The General Labor Inspectorate : It is the specialized body of the Ministry of Labor, responsible for monitoring and control, as well as information and advice, regarding the application of legislative and regulatory provisions related to working conditions, health, and safety in the workplace, which are primarily ensured by labor inspection. National Institute for the Prevention of Occupational Risks : It is under the supervision of the Ministry of Labor, Employment, and Social Security and carries out its activities for the benefit of employees and companies. It provides technical assistance to companies in general: studies and research, training in prevention, technical and documentary assistance, information (newspapers, posters, brochures, audiovisuals, website). The laboratories that assist the INPRP in fulfilling its missions are: Metrology and Environments Laboratory, Pollutant Analysis Laboratory, Ergonomics Laboratory, Biology Laboratory, and OPREBATPH (The Organization for the Prevention of Occupational Risks in Building, Public Works, and Hydraulics Activities). Ministry of Health, Population, and Hospital Reform. Collaborates by: -The sub-directorate of occupational health Its missions are: standardization of occupational health services and activities, evaluation of programs, and control of occupational health activities through occupational health inspectors distributed across all health and population departments. - (National Institute of Public Health): He oversees the conduct of studies and research in public health, providing the supervising ministry with the scientific and technical tools necessary for the development of health action programs. -Occupational physician: He accompanies and advises the employer and employees on the implementation of risk prevention measures. 1.12. Master the indicators related to workplace accidents and occupational diseases A. Work accident (WA): The definition of a work accident by the Social Security Code is as follows: "An accident is considered a work accident, regardless of its cause, if it occurs as a result of or in the course of work to any employee or worker, in any capacity or place, for one or more employers or business leaders." They therefore include traffic accidents occurring during work-related travel. The accident is characterized by the violent and sudden action of an external cause resulting in a bodily injury during work, and having a connection with the work. Work accidents are divided into two categories: a) Workplace accidents. b) Commuting accidents (considered as work-related accidents). Commute accident: a commute accident is also recognized as a work-related accident if it occurs between the workplace and the usual meal place, the stable main or secondary residence, or any other usual place dictated by a family reason, and if the route has not been interrupted or diverted for a personal reason unrelated to the necessities of daily life or independent of employment. B. Occupational Disease (OD): An occupational disease is a health impairment resulting from a series of slowly evolving events to which a specific origin and date cannot be assigned, contracted during work. "A disease is considered occupational if it is a direct consequence of a worker's exposure to a physical, chemical, or biological risk, or if it results from the conditions in which they carry out their professional activity and if it is listed in one of the tables annexed to the Social Security Code." To be recognized as an occupational disease, the profession must be on the indicative list or the restrictive list of occupational disease tables. C. Occupational Health and Safety Indicators In addition to being necessary for the effective implementation of Management Systems of the Occupational Health and Safety, the use of OHS indicators has almost become a legal obligation. Indeed, since 1991, employers have had a legal obligation to ensure safety and protection. Health and Safety indicators are Safety outcome indicators. These results are generally oriented according to two dimensions: the frequency and the severity of undesirable events. These indicators are generally constructed in the form of an index or a rate. Severity indicators The indicators measuring severity are calculated by counting the number of "lost" work hours compared to the number of work hours performed. Severity index The severity index is calculated by dividing the total number of Permanent Partial Disabilities (IPP) by the total number of hours worked, all multiplied by a constant 1,000,000 Severity rate The severity rate is calculated by counting the number of days lost due to incapacity.Temporary (IT) divided by the total number of hours worked, all multiplied by a constant of 1,000. Frequency indicators The frequency of adverse events is generally expressed by counting the number of workplace accidents, occupational diseases, or even days lost due to temporary incapacity (TI). Frequency rate The frequency rate indicates the number of undesirable events occurring over a reference time period. This frequency rate is calculated based on a base of 1,000,000 hours of work, which corresponds to the average number of stoppages experienced by a group of employees who have worked one million hours. The frequency rate relates the number of workplace accidents to a duration of exposure. It is the most commonly used traditional indicator in companies to communicate about occupational health. Frequency index The frequency index is calculated by taking as a reference not a period of time but the number of employees in the organization. This frequency index is also called the incidence index. These severity and frequency indicators, once calculated, allow for tracking the evolution of the risk level for the company, activity, or sector. The company can thus, by comparison, position itself within its industry or sector. 1.13. Risk Assessment The risk assessment phase involves determining a risk level based on a combination of factors. The results of a risk assessment depend on the people conducting it. Frequency The assessment of frequency takes into account: - the frequency of exposure to the hazard and/or the number of accidents, also taking into account the number of people exposed and/or affected; - existing preventive measures. The frequency factor is improved by preventive actions. Severity of the damage The severity factor is improved by protective actions. Table 1.2: Possible scales of frequency, probability of occurrence of damage, and the severity of a damage: Criticality Matrix The criticality matrix is a tool that allows distinguishing a critical area from a non-critical area. The criticality matrix relates frequency and severity. It can take different forms depending on the defined scales. Figure I.6: Example of risk assessment, Priority 1: reduction of risk necessary and immediate. Priority 2: reduction of necessary but not immediate risk. Priority 3: reduction of unnecessary risk 1.14. Creation and analysis of a cause tree: This is the phase of formulating hypotheses regarding the causes of the accident. This phase follows the initial collection of data and facts (related to the consequences, the timeline, and the first information about the circumstances of the accident). Generally speaking, this phase of hypothesis formulation serves to structure: ▪ The known facts and results, ▪ The unknown information that would require future data collection and analysis. This phase primarily aims to clarify: what happened, under what circumstances, oh why. Principles for creating a Cause and Effect Diagram: a) Key Principles: The accident analysis using the fault tree method is based on the following key principles: o Identification of direct causes, o Deductive method starting from a final event (accident, near accident), o Decomposition of facts into elementary, independent events, o Evaluation of the logical connections between events and combinations of events, o Provision of a graphical representation, Preparation of the formulation of the most plausible scenario by providing necessary and sufficient causes to confirm or rule out. b) General principles: It is a deductive method that, starting from a feared event, a consequence, or an accident, aims to determine the sequences or logical combinations of events that could ultimately have led to the accident. It focuses on determining the direct causes (equipment failures, human actions) as opposed to the root causes. It allows tracing back from causes to causes until reaching the basic events that could be the origin of the feared event (near miss) or the accident. Whatever the nature of the identified basic elements, the root cause analysis is based on the following principles: or these events are independent; or they will not be broken down into simpler elements due to lack of information, interest, or because it is impossible; The analysis by fault tree of an accident or near-accident (feared event) can be broken down into three successive steps: o definition of the accident or feared event studied, or the development of the cause-and-effect tree, o evaluation of the plausibility of the causes (removal or conservation of branches) in order to define the (and by default the) most probable scenario(s). It is appropriate to add to these steps a preliminary stage of understanding the system and prior knowledge of the risks. c) Starting the cause tree from the final or feared event (accident or near- accident): The definition of the final or dreaded event is a crucial step in the construction of the tree. We understand that the more precisely this event is defined, the simpler the development of the cause tree will be. From this final event, it is necessary to investigate the immediate, necessary, and sufficient causes (INS). In other words, it is appropriate to ask the following questions What cause(s) or event(s) were necessary to achieve this consequence? Is this cause sufficient to provoke this consequence? The systematic search for immediate, necessary, and sufficient causes (INS) is therefore the basis for the construction of the tree. Gather the facts The collection of facts is the starting point of the analysis. A fact can be: An action (Examples: Abdel is carrying his toolbox in his left hand; the employee fell on his head; the cart tipped over parallel to the truck). A state (Examples: Yanis works barehanded; Adam was not wearing safety shoes). A fact is precise, concrete, and verifiable. It is in affirmative form (Example: the employee, aged 28, is a crane assembly assistant). A fact is neither an opinion ("in my opinion..."), nor a judgment ("he works poorly"), nor an interpretation ("I think he was late"). Example: he arrived at 8:45 does not mean the same thing as "I think he was late. The collection of facts must be carried out at the very site of the incident/accident, as quickly as possible and with all the people involved. It highlights the multi-causality of the accident. The collection of facts is an inquiry into the different elements of the work situation: - The individual (the victim): who is he? His age, his skills, his seniority in the job, his training, etc. (Example: Salim is a qualified electrician.) He has been working in the company for 10 years. - The task he was performing: what exactly was he doing at the moment of the accident? How was he going about it? For what reasons did he do this work in this way? Were there any modifications compared to the usual operating procedure? Was there anything unusual? Etc. (Example: the operation involved loading a truck using a self-propelled forklift). - The individual (the victim): who is he? His age, his skills, his seniority in the job, his training, etc. (Example: Salim is a qualified electrician.) He has been working in the company for 10 years. - The environment in which the activity takes place (physical, relational, organizational): what was the organization of the work? What are the environmental factors such as noise, cold, etc.? Is it an isolated job or not? (Example: the terrain was sloped at about 8%, the order had to be delivered the same evening). Construct the cause-and-effect tree The construction is organized from right to left with the starting point being the lesion (ultimate fact or incident). A graphic code allows distinguishing between the two types of facts collected. The facts corresponding to an unusual nature compared to the normal course of activity The facts corresponding to a permanent nature Each fact is linked to the following fact by a cause-and-effect relationship. Each fact collected systematically leads to the following questions: What was needed for this to happen? Is it necessary? Is it sufficient? Each time we answer NO to the question: Is it sufficient? Another avenue opens up, from which the entire set of three questions is renewed, until no new avenues can be found. The found facts are organized according to three types of connections. 1. A chain: a fact (Y) – a precursor (X) Example: the employee slipped (X), he fractured his wrist (Y). 2. A conjunction: one fact (Y) – several antecedents (X1, X2); Example: the floor is wet (X1) and the employee is wearing dress shoes (X2), the employee slipped (Y). 3. A disjunction: several facts (Y1, Y2) – one antecedent (X). Example: the plates broke (X), the employee fell from a height of 6 m (Y1) onto a concrete floor (Y2) When there is no connection between two events, they are independent events. Example of application The analysis of an incident/accident revealed the following facts: Heavy rain, Speed too high; Accidente; Late; Slippery road. To construct the cause tree, we ask two questions for each fact starting from the injury What was needed for? Is it enough? 1.15. Conclusion Throughout history, human beings have constantly faced bodily accidents, whether minor or severe, as well as significant events and phenomena that have profoundly impacted them. Among these accidents, those caused in the workplace, which result in minor accidents, with a limited number of victims and damage that does not exceed the confines of the workshop or factory; these are workplace accidents and, to some extent, occupational or work-related diseases. This chapter aimed to enlighten the reader on the impacts of transformations in the world of work on the health and safety of the workforce. The field of occupational health and safety is a dynamic, evolving, and perpetually advancing domain. Thus, we advise students to refer to certain websites (such as the one from Ministry of Labor, Employment, and Social Security), to verify the sustainability of the legislation.