Exercises: Health and safety standards

Explain what personal protective equipment (PPE) is, name three common examples in a technology workshop, and indicate which part of the body each protects and against what risk.

Before using a pillar drill, several things must be checked. Write three safety rules that you must always apply before starting to drill, and explain the risk that each one avoids.

The figure shows the pictograms of five items of personal protective equipment, with a question mark below each one, as shown in the figure.

Name the protective equipment represented by each pictogram and explain what risk it prevents. Then, indicate which ones you would use to cut wood with a power saw and why.

Explain the difference between risk (possibility of suffering harm) and accident (harm that has already occurred), giving an example from the workshop for each concept.

Safety signs use standardised colours. Explain what each one indicates: yellow (hazard warning), red (prohibitive or fire-fighting equipment) and green (exits and rescue equipment), and give an example of each type of sign that exists in your school.

What does an FFP2 respirator mask protect against, and in which workshop tasks should you use it (sanding that generates dust, varnishing, soldering)? Explain the difference between it and a surgical mask.

Explain why eating and drinking are forbidden in the workshop, relating it to the contamination of work surfaces (solvent residues, metal dust) and the focus required near machinery.

A classmate gets a minor cut on their hand while working with you. State the correct first steps (inform the teacher, wash and cover the wound, do not remove embedded objects) and mention two things you MUST NOT do.

A student is going to varnish a model in the workshop with the windows closed and without a mask or gloves. Identify the risks of this situation, classify them (inhalation, skin contact, etc.), and indicate the appropriate PPE and ventilation measures.

The risk generated by a machine (impacts, cuts, entanglement) is not the same as that generated by a chemical product (burns, fumes). Explain the difference and describe two specific preventive measures for each type of risk.

Explain why it is dangerous to work with loose clothing, untied laces or loose long hair near machines with rotating parts (drill, lathe), and what the risk of entanglement entails. State how individuals using them should be dressed and equipped.

A student is going to use an angle grinder without a protective guard and without safety goggles. Identify the specific risks (flying particles into eyes, disc breakage, sparks) and describe the necessary measures before and during the work (PPE, inspection of the disc and guard, area clear of people and flammable materials).

Untidiness causes accidents. Explain how (badly stored tools falling, cables on the floor, material scraps causing slips or fires) and write three rules of tidiness and cleanliness for the workshop, indicating the specific risk each one avoids.

Chemical product labels carry standardised pictograms. Explain what a 'corrosive' pictogram and a 'flammable' pictogram warn you about, and what precautions of use and storage each of these products requires in the workshop.

Analyse common electrical risks in a workshop (damaged cables, extension leads overloaded with several machines, appliances near water sources) and propose a specific preventive measure for each of these three risks.

Machines have guards and safety interlocks that some people bypass 'to go faster'. Explain what an interlock is (the machine does not operate with the guard open), what typical accident it avoids, and why bypassing it turns a safe machine into a hazard.

In the manufacturing workshop, an enclosed technical filament (ABS) 3D printer has been installed on the same workbench where a drill press is operated for machining metal profiles. Two students work in parallel: one adjusts parameters and removes parts from the heated bed at 100 °C, and the other machines aluminum plates.

1. a) Identify and justify three critical risk incompatibilities or interferences generated by this proximity (analyze thermal risks, mechanical risks due to flying chips, and environmental risks due to volatile emissions).
2. b) Resolve the regulatory conflict regarding Personal Protective Equipment (PPE): explain why using thermal protective gloves to handle the printer poses an unacceptable risk of entanglement in the drill press, and what strict protocol must be applied.
3. c) Design a technical retrofitting proposal for the workstation based on collective protections and safety engineering (chip shields, localized extraction, safety distances) to physically eliminate the interference between both activities.

During the manual cutting of polymer sheets for a prototype, a student suffers a deep cut to their hand with a utility knife. The preliminary incident report concludes: "Cause of the accident: student recklessness for cutting towards themselves, working in a rush, and not wearing cut-resistant gloves".

1. a) Technically refute this preliminary report based on the theory of accident causation. Apply the root cause tree method differentiating between verifiable objective facts, work variations, and root causes at different levels (tooling/equipment, working method, environment, and workshop organization).
2. b) Explain why blaming the human factor ("carelessness" or "rushing") does not prevent the accident from recurring.
3. c) Design two technical modifications to the tooling or the guiding and clamping system that physically prevent contact between the blade and the operator's hands, making the process intrinsically safe.

A stamping line produces 120 parts/hour. In an attempt to increase production by 15 %, the foreman proposes bypassing the safety light curtain of a mechanical press (which adds 4 s of cycle time per check), claiming that "the operators are very experienced, nothing has ever happened, and safety regulations only serve to waste time and money".

1. a) Use the INSST simplified risk assessment method (NTP 330) to evaluate the workstation before and after removing the light curtain. Assign and justify coherent values for the Deficiency Level (ND), Exposure Level (NE), and Consequence Level (NC), calculating the resulting Risk Level (NR) and interpreting its regulatory significance.
2. b) Refute the foreman's claim by analyzing the concept of residual risk and the fallacy of relying on the absence of previous accidents when the potential severity of failure is a traumatic amputation.
3. c) Carry out an economic-technical balance comparing the alleged benefit of manufacturing 18 more parts per hour against the direct and indirect costs (sick leave, compensation, line downtime, expert appraisals, and inspections) resulting from a single serious accident.

In a manufacturing and prototyping workshop, three tasks are performed simultaneously under the following working conditions:

1. Drilling of steel flat bars: 12 operators, 4 hours per day; machine without a chip protective guard or foot-accessible emergency stop; use of cutting fluid without continuous recycling.

2. Degreasing and cleaning of parts with volatile organic solvents: 2 operators, 40 minutes per day in an enclosed room without mechanical ventilation or extraction hood.

3. Soft electronic soldering with tin-lead: 10 students, 2 hours per week; workbenches with shared extraction arms but with saturated filters and without periodic inspection.

1. a) Build a 3 × 3 risk assessment matrix (Probability: Low, Medium, High × Severity: Slight, Serious, Very Serious) and place the main risks of each of the three tasks with justification, based on exposure data and potential harm to health.
2. b) Suppose the workshop management has a limited budget and decides to spend it entirely on buying disposable FFP2 masks for the soldering students because "they are the most numerous". Technically justify why this decision is flawed according to the principles of preventive action and reorganize the investment plan by prioritizing interventions that provide the greatest reduction in overall risk.

During the machining of a shaft on an engine lathe, the wide sleeve of an operator's coat becomes caught by friction in the rotating feed rod. The operator cannot reach the emergency stop push button installed on top of the headstock with their free hand, and the lathe takes 4,5 s to stop by inertia after a coworker hits the main switch, causing severe fractures.

1. a) Critically analyze the machine's stopping and protection system, distinguishing between integrated protective measures (engineering and machine design) and measures dependent on human behavior.
2. b) Design three specific technical improvements for the lathe, compliant with the Machinery Directive and the UNE-EN ISO 13850 standard (for example, emergency stop bar or pedal, electrodynamic brake, and protective guard with interlocking microswitch), justifying how each reduces stopping time or prevents entanglement regardless of the operator's clothing.
3. c) Justify why, in industrial safety design, an organizational procedure (such as "prohibiting loose clothing") is never considered a sufficient barrier on its own against an unguarded moving part.

The self-protection and emergency plan of a 140 m² (14 m × 10 m) industrial workshop is audited; it has a single exit door to the outside that opens inward. There are three work areas in the workshop: machining with lathes and milling machines (cutting oils and three-phase panels), carpentry (accumulated sawdust and sanders), and storage of varnishes and solvents. The current equipment consists of a single water-based extinguisher (water with additives) located next to the solvents and an exit sign at 1,20 m from the floor covered by a bulletin board.

1. a) Diagnose and refute with justification four serious regulatory deficiencies regarding fire safety and evacuation (classify the types of fire present according to the UNE-EN 2 standard and reason the deadly hazards of using the existing extinguisher in two of the three areas).
2. b) Redesign the provision and distribution of fire extinguishing media: determine which extinguishing agents (ABC powder, CO₂) must be installed, how many are required to cover the floor area while respecting the maximum regulatory travel distance (15 m), and at what exact locations they should be mounted.
3. c) Justify what structural and signage modifications the evacuation route requires and design an evacuation protocol assigning specific roles (evacuation coordinator, person in charge of general electrical shut-off, and roll call at the outside assembly point).

In a carpentry and school furniture manufacturing workshop, operators perform dry sanding of particleboard and hardwoods. Occupational hygiene measurements indicate that the respirable fraction of wood dust exceeds the Occupational Exposure Limit (VLA) by 250 %, with the aggravating factor that hardwood dust is classified as a carcinogen. Management decides to give each worker an FFP2 mask at the beginning of the week and consider the problem solved. After two hours of use, many operators pull the mask down to their necks claiming breathing difficulty and heat.

1. a) Critically analyze why management's strategy is a preventive and technical failure: explain the intrinsic limitations of PPE against prolonged exposure and why the Occupational Risk Prevention Act establishes a mandatory hierarchy of controls.
2. b) Design a comprehensive action plan structured into the four levels above PPE (elimination, substitution, technical/engineering controls, and organizational measures). Propose at least one concrete, justified, and feasible technical measure for each level, arguing how each contributes to reducing airborne concentration without relying on worker behavior.

In a machining workshop with bench grinders and drill presses, several students refuse to wear eye protection glasses, arguing: "We have been working like this all term and nothing has ever flown into anyone's eyes; the probability of a chip hitting an eye in a 50-minute session is tiny, barely 1 in 400 (0,0025)".

1. a) Mathematically dismantle this false sense of security: calculate the cumulative probability of at least one eye accident occurring in a group of 18 students working under these conditions over a course of 35 practical sessions. Interpret the numerical value obtained compared to the students' initial claim.
2. b) Apply the Bird/Heinrich accident pyramid model to explain the cause-and-effect relationship between the hundreds of micro-incidents that go unnoticed ("near misses" or chips grazing the face) and the inescapable probability of a disabling eye injury occurring.
3. c) Design a combined intervention of preventive engineering (on the machines themselves) and safety culture management that is not limited to coercive punishment, justifying why physical barriers are always preferable to mere surveillance.

Unit challenge. Imagine that you must design an auxiliary accessory for your study area that improves ergonomics or eliminates an electrical hazard, using additive manufacturing.

1. Data collection and prevention: Measure your device or charger with millimetre precision. Consult the INSST website for screen ergonomic risks or electrical overload risks and define which specific problem you will mitigate.

2. Digital prototyping (Tinkercad): Model in 3D an ergonomic stand or functional cable grommet tailored to your actual measurements, incorporating an assembly tolerance of $0,5\text{ mm}$ and optimizing the geometry for FDM 3D printing (avoiding overhangs greater than $45^\circ$ without support).

3. Technical sheet and safety: Export the design and write a brief data sheet in LibreOffice including: planned parameters ($20\,\%$ infill), estimated filament mass, and the health and safety protocol for the school workshop (ventilation against VOCs and ultrafine particles, prevention of burns above $200\text{ }^\circ\text{C}$, and use of PPE).

Assessment criteria:

• Rigour in taking real measurements and justification of the ergonomic or safety risk mitigated.

• Technical feasibility of the 3D model considering the constraints of additive manufacturing.

• Accuracy of the health and safety rules protocol during the printing process.