Manual de ergonomía, Apuntes de Ingeniería Industrial

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CONTENTS

ACKNOWLEDGEMENTS............................................................................................... i

CONTENTS (Cont’d)

i.

ACKNOWLEDGEMENTS

This manual was originally developed by BP and University of Wollongong. The Occupational Hygiene Training Association Ltd would like to acknowledge the contribution of these organisations in funding and developing the material and is grateful for their permission to use and modify it.

Development of the manual was led by Alison Bell CPE, and Fiona Weigall CPE, of the School of Health Sciences at the University of Wollongong, Australia. Selected content has been drawn from ”Practical Ergonomics” by Ms Barbara McPhee with the permission of Coal Services Australia. Considerable assistance was received from the following individuals or organisations and the authors would like to express their appreciation for the support received.

Dr Brian Davies - University of Wollongong Ms Barbara McPhee, CPE, Fellow HFESA Ms Cara Gray, Metrographics Ms Airdrie Long, CPE Ms Jennifer Long, CPE Ms Katrina James, BlueScope Steel Pty Ltd Mr Ken Cram, Coal Services Health Mrs Susan Davies Mr John Henderson British Occupational Hygiene Society Brian Cox – University of Wollongong Roger Alesbury – BP plc Terry McDonald – BOHS Tom Cliff – BP plc Graham Reeves – BP plc Dr Mike Stevenson, CPE, Fellow HFESA

Supported by

This work is licensed under a Creative Commons Attribution Works Licence-No Derivative

ii.

ABBREVIATIONS

ASCC Australian Safety & Compensation Council

BOHS British Occupational Hygiene Society

BPM Beats Per Minute

CCOS Canadian Centre for Occupational Health & Safety

CEN European Committee for Standardisation

CIE International Commission on Illumination

COP Code of Practice

CTD Cumulative Trauma Disorder

dB Decibels

EAV Exposure Action Value

ELV Exposure Limit Value

EMG Electromyograph

EU European Union

FMEA Failure Mode and Effect Analysis

FTA Fault Tree Analysis

HAVS Hand Arm Vibration Syndrome

HAZOP Hazard and Operability studies

HDM Hypothetical-Deductive model

HSE Health & Safety Executive (UK)

HTA Hierarchical Task Analysis

IEA International Ergonomics Association

ILO International Labor Organisation

ISO International Organisation for Standardisation

JND Just Noticeable Difference

KPI Key Performance Indicator

LTIFR Lost Time Injury Frequency Rate

MAC Manual Handling Assessment Charts

iv.

UK United Kingdom

UL Upper Limb

USA United States of America

VDT Visual Display Terminal

VDU Video Display Unit

VDV Vibration Dose Value

WBGT Wet Bulb Globe Temperature

WBV Whole Body Vibration

WHO World Health Organisation

WRAC Workplace Risk Identification and Control

WRMSD Work-related Musculoskeletal Disorders

WRULD Work-related Upper Limb Disorders

1. COURSE OVERVIEW

1.1 INTRODUCTION

This Course has been developed so that it follows the international module syllabus W506 – Ergonomics Essentials published by the British Occupational Hygiene Society (BOHS), Faculty of Occupational Hygiene. The BOHS administers a number of such modules; further information on which can be obtained by visiting the BOHS website at www.bohs.org.

At the time of publication every care has been taken to ensure all topics covered in the BOHS syllabus for the subject (W506) have been included in this Student Manual. Providers of training courses should check the BOHS website for any changes in the course content.

The developers of this Student Manual take no responsibility for any material which appears in the current BOHS syllabus for Module W506 which is not covered in this manual.

1.2 AIM OF COURSE

To provide the student with a broad based introduction to ergonomics principles and their application in the design of work, equipment and the workplace. Specific consideration is given to musculoskeletal disorders, manual handling, ergonomic aspects of the environment, as well as to the social aspects and relevant international standards.

1.3 LEARNING OUTCOMES

On successful completion of this module the student will be able to:  Describe and apply ergonomics principles to promote safety, health and productivity  Outline the process of ergonomics risk assessments  Explain the causes of upper limb disorders

2. OVERVIEW OF ERGONOMICS

This topic outlines general information about the domain of ergonomics, and provides an overview of human characteristics, capacities and the specific considerations for the human in a work system.

2.1 GENERAL PRINCIPLES

2.1.1 Definition

The word „ergonomics‟ is derived from an Ancient Greek word meaning „rules‟ or „study of work‟. It is also referred to as „human factors (in design)‟. Ergonomics is concerned with appropriate design for people - the design of systems, processes, equipment and environments so that tasks and activities required of them are within their limitations but also make the best use of their capabilities. Therefore the focus of the design is on the person or a group of people. This is often termed “user-centred design”.

Ergonomics is a science; it is a rigorous, user-centred approach to research and design. It is also a philosophy and a way of thinking. It is applied widely in areas such as aviation and other transport systems, sport, education, public facilities, the home, recreational equipment and facilities and in the workplace generally. In fact, the whole community benefits from ergonomics design. Ergonomics considers the whole work system, and the effects of the system on human and system performance (see Figure 2.1).

Ergonomics has three domain areas: Physical ergonomics, Cognitive ergonomics and Organisational ergonomics.

Adapted from Stevenson (1999) Figure 2.1 - Ergonomics: The Systematic Study of the Human at Work

2.1.2 History of Ergonomics Ergonomics in the United Kingdom arose out of World War 2 when scientists were asked to determine the capabilities of the soldier in order to maximise efficiency of the fighting man (Pheasant, 1991). In the United States, ergonomics arose out of psychology and cognitive function in the aviation industry and was termed „human factors‟. Today these terms are used interchangeably. Since the industrial revolution, work has turned away from its agricultural base to city-based work environments. Further changes have occurred in recent times with an increase of females in paid employment, an increasing age of workers, an internationalisation of the workforce and an increased trend to contract or outsource work. All of these changes have implications for design of equipment and work systems, and a role for ergonomics.

Societal and Cultural Environment External Environment – Legislation, Economy, Standards Organisation Structure & Job Design Workplace Environment

Workstation Worker

Output Input Orders/ Goods/ Services Planning

2.1.4 Aims, Objectives and Benefits of Ergonomics

The overall aim of ergonomics is to promote efficiency and productivity and ensure that the capacities of the human in the system are not exceeded. The word „optimum‟ is often used in ergonomics and refers to the balancing of the needs of people with real-life limitations such as the availability of solutions, their feasibility and costs. Successful solutions depend on solving the real, rather than the apparent problems. This in turn requires careful observation and analysis.

Ergonomics problems and solutions may not transfer exactly from one country, region or industry to another – they have a social context. Although the basic human characteristics are the same they take on local differences for a range of reasons – geographical, social, economic or historical. It can be described as „the way we do things around here‟ and relates to the culture of a country, region, industry and/or company. Consequently, ergonomics issues should be identified and addressed locally because each set of circumstances is different. Importing solutions without reference to local issues and resources may fail.

In terms of cost benefits the advantage of ergonomics changes is that they will make the job faster, easier, safer and enhance productivity. It is important to assess the benefits in the short, medium and long term, as expensive equipment and process changes may take some time to take effect.

2.1.5 Fitting the Job to the Person and Person to the Job, Occupational Ergonomics At work ergonomics is applied to the design of the workplace and tasks and to work organisation. It is often referred to as occupational ergonomics within the OHS community. As such it aims to promote health, efficiency and wellbeing in employees by designing for safe, satisfying and productive work.

Positive performance factors such as worker comfort, well being, efficiency and productivity are all considered in determining how to achieve an acceptable result. In this respect ergonomics is different from many other areas of OHS hazard management, where the primary aim is to reduce risks of injury or disease. Good ergonomics in the workplace should improve productivity and morale and decrease injuries, sick leave, staff turnover and absenteeism.

When analysing work and how it can be improved from an ergonomics point of view there are five elements that need to be addressed:

1. The worker : the human element of the workplace. Employees have a range of characteristics that need to be considered including physical and cognitive capacities; experience and skills; education and training; age; sex; personality; health; residual disabilities. An individual‟s personal needs and aspirations are also considered.
2. Job/task design : what the employee is required to do and what they actually do. It includes job content; work demands; restrictions and time requirements such as deadlines; individual‟s control over workload including decision latitude, working with other employees; and responsibilities of the job.
3. Work environment : the buildings, work areas and spaces; lighting, noise, the thermal environment.
4. Equipment design : the hardware of the workplace. It is part of ergonomics that most people recognise and includes electronic and mobile equipment, protective clothing, furniture and tools.
5. Work organisation : the broader context of the organisation and the work and how this affects individuals. It includes patterns of work; peaks and troughs in workload, shiftwork; consultation; inefficiencies or organisational difficulties; rest and work breaks; teamwork; how the work is organised and why; the workplace culture; as well as the broader economic and social influences.

In occupational ergonomics, the physical design aspects of work or the „hardware‟ may be only part of the problem and therefore part of the solution. In some cases it may be a small part. Other factors influence the development of a problem including work organisation and task design, job content, work demands and control over workload, support and training. Usually these aspects require ergonomics to be integrated into the broader work systems.

Therefore to determine if an optimum solution has been achieved the people who will perform the work (the „who‟), the nature of the tasks (the „what‟) and the context in which they are done (the „where‟, „when‟ and the „how‟) need to be considered.

2.1.7 Human Characteristics, Capabilities and Limitations

As outlined above, the human characteristics and capabilities Ergonomists consider are the physical and cognitive capacities of the human at work. These capacities are affected by personal characteristics such as gender, age, pre-existing injury or disability and work organisation factors such as shift work, intensive work cycles and issues such as low morale. We will examine these factors throughout this course.

2.1.8 Human Error

„Human error‟ is a term often used to describe the cause of an accident. Human error has been defined as an inappropriate or undesirable human decision or behaviour that reduces, or has the potential for reducing effectiveness, safety, or system performance. Ergonomics applied to system design will make the system „error tolerant‟ by considering the cognitive capacity of the human to make decisions in a number of situations. Human error is an unintentional act and is distinguished from a pre-mediated violation of rules and/or procedures by an individual.

Conversely then, „human error‟ ascribed to accident causation is really indicative of poor design. The „failure‟ that results from this can be immediate or delayed. (HSE, 2007, p.10.)

In order to make systems „error tolerant‟, we need to understand why and how people make errors so that we can design the system appropriately.

Active failures are usually made by operators at the front line. These failures have immediate consequences.

Latent failures are made by personnel removed from the „front lint‟, for example designers and managers. Latent failures are system failures and include poor design of plant, processes and/or procedures (eg: communication, roles, responsibilities, training). These types of failures typically pose a greater risk to health and safety. (HSE, 2007.)

A useful diagram to illustrate the types of human error and violations (Human Failure) can be found in the HSE book: „Reducing Error and Influencing Behaviour‟, and has been reproduced below.