Lesson Notes By Weeks and Term v4 - SHS 2
HEALTH AND SAFETY IN ENGINEERING PRACTICE
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HEALTH AND SAFETY IN ENGINEERING PRACTICE
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Engineering
Class: SHS 2
Term: 1st Term
Week: 10
Grade code: 2.1.2.LI.4
Strand code: 1
Sub-strand code: 2
Content standard code: 2.1.2.CS.1
Indicator code: 2.1.2.LI.4
Theme: ENGINEERING PRACTICE
Subtheme: HEALTH AND SAFETY IN ENGINEERING PRACTICE
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In Ghana, we see engineering in action every day – from the welder in Kokompe fixing a gate, to the masons building new houses in our communities, to the technicians maintaining equipment at the Tema Oil Refinery. All these jobs involve potential dangers, or 'hazards'. An accident can cause serious injury, stop a project, and cost a family or company a lot of money. Therefore, understanding how to identify and control these hazards is one of the most important skills for any engineer or technician. This lesson will equip you with the knowledge to create safer working environments for yourselves and others by explaining the systematic ways to manage workplace dangers.
This lesson focuses on a systematic approach to making engineering work safer. We start by understanding the problem (hazards and risks) and then learn the best ways to solve it (control measures). 2.1. Fundamental Definitions Hazard: A hazard is anything with the potential to cause harm. It is the source of danger. Think of it as a condition or an object that could lead to an accident. Example: A puddle of oil on the floor of an auto-mechanic's workshop is a hazard. The potential harm is slipping and falling. Example: A faulty electrical wire with exposed copper is a hazard. The potential harm is electric shock. Risk: Risk is the likelihood (or probability) that harm will actually occur from a hazard, combined with the severity of that harm. Hazard: Puddle of oil. Risk: If the puddle is in a busy walkway, the risk of someone slipping is high. If it's in a forgotten corner, the risk is low. Control Measure: A control measure is an action, device, or procedure put in place to eliminate a hazard or reduce the risk associated with it. Our main goal is to implement effective control measures. 2.2. Types of Hazards in Engineering
To control hazards, we first need to identify them. We can group them into categories: Safety Hazards: These are the most common and obvious dangers. Examples: Unguarded machinery (like a grinding wheel without its cover), working at height (on scaffolding), faulty electrical equipment, spills on the floor (slips, trips, and falls). Physical Hazards: These are sources of harm from the environment that can affect the body without necessarily touching it. Examples: Loud noise from a generator or metal cutter (can cause hearing loss), extreme temperatures (heat stress from welding), radiation (from welding arcs), vibrations from a jackhammer. Chemical Hazards: These involve exposure to any chemical in the form of a solid, liquid, or gas. Examples: Welding fumes, cement dust, cleaning solvents, battery acid, paint fumes. These can cause breathing problems, skin irritation, or long-term diseases. Ergonomic Hazards: These occur when the type of work, body positions, and working conditions put a strain on your body. Examples: Poorly designed workstations, frequent lifting of heavy items (like cement blocks), repetitive motions (like turning a screwdriver all day). These can cause muscle and back injuries. Biological Hazards: Hazards from living organisms. Examples: Bacteria or viruses from working in waste management or with contaminated water systems. 2.3. The Hierarchy of Controls: The Core of the Lesson
We don't just pick any control measure. There is a system for choosing the most effective ones. This system is called the Hierarchy of Controls. It is often shown as an inverted pyramid, because the most effective controls at the top are best, while the least effective ones at the bottom should be our last resort.
Let's break it down from most effective to least effective: Elimination (Most Effective) What it is: Physically remove the hazard completely from the workplace. If the hazard isn't there, it can't cause harm. This is the best possible solution. Ghanaian Example: A construction company needs to join two steel beams high up on a building. Instead of having welders work at that dangerous height (hazard: working at height), they redesign the process to weld the beams together on the ground first and then use a crane to lift the completed section into place. The hazard of welding at height has been eliminated. Substitution What it is: Replace the hazardous thing or process with a safer alternative. Ghanaian Example: A furniture maker in Accra uses a strong, solvent-based glue that releases harmful fumes (chemical hazard). To make the workshop safer, they switch to a newer, water-based glue that is just as strong but non-toxic. The hazardous chemical has been substituted with a safer one. Engineering Controls What it is: Isolate people from the hazard by making a physical change to the work environment or equipment. This doesn't eliminate the hazard, but it creates a barrier. Ghanaian Example 1 (Isolation): A large generator at a factory produces a deafening noise (physical hazard). The company builds a soundproof enclosure around the generator. The noise hazard still exists, but the workers are protected from it. Ghanaian Example 2 (Guarding): A carpenter's saw has a very sharp, fast-moving blade (safety hazard). A permanent safety guard is installed that covers the blade, preventing the operator's hands from getting near it. Administrative Controls What it is: Change the way people work. These are procedures, rules, and training to make work safer. Ghanaian Example 1 (Training): A new apprentice is taught the correct and safe way to use a grinding machine before they are allowed to operate it. Ghanaian Example 2 (Procedures & Signage): An ECG substation has high-voltage equipment. "DANGER: HIGH VOLTAGE - NO UNAUTHORISED ENTRY" signs are posted. This is an administrative control warning people of the hazard. Ghanaian Example 3 (Job Rotation): At a block factory, instead of one person lifting blocks all day (ergonomic hazard), workers are rotated every two hours to different tasks like mixing, moulding, and stacking. Personal Protective Equipment (PPE) (Least Effective) What it is: Equipment worn by the individual to protect them from a hazard. This is the last line of defence. It should only be used when the other controls are not feasible or to supplement them. It is the least effective because if the PPE fails or is not worn correctly, the worker is fully exposed to the hazard. Ghanaian Example: A mason on a construction site wears a hard hat to protect against falling objects, safety boots to protect their feet, and gloves to protect their hands from wet cement. The hazards (falling objects, sharp materials, corrosive cement) are still there, but the worker is protected.