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Work Environment Physics

Katarzyna Jach, Ph.D.

Katarzyna.jach@pwr.edu.pl

http://ksz.pwr.edu.pl/kadra/katarzyna.jach/

B1 building r. 415c

Grading requirements

Passing the final test (last two lectures 27.05

– first term and 3.06 – second term)

Alternative: grading by activity

Two or three small tests – for passing you need a

half of points

Few homeworks

Group works

Answers / questions

Information about grading by activity 20.05

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After the course you’ll get to know:

basic principles of physics with emphasis on

the work environment factors

the effects of some environmental factors

on the human body work and workload

basic ergonomic principles, tools and

methods for the assessment of workload

some legal and normative basis for

occupational safety and ergonomics

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Work Environment Physics =

Ergonomics

Ergonomic design

Work environment factors

Microclimate

Noise

Lighting

Ergonomic workload

Accessibility, usability ….

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Ergonomics

Nazwiskiem Ergonomji, wziętemod wyrazu greckiego ergon – pracai nomos – prawo, zasada,oznaczamy Naukę o Pracy czyli oużywaniu nadanych człowiekowiod Stwórcy siły i zdolności.

Wojciech Bogumił Jastrzębowski, 1857, Rys

ergonomji czyli nauki o pracy, opartej na

prawdach poczerpniętych z Nauki Przyrody

(The Outline of Ergonomics, i.e. Science of

Work, Based on the Truths Taken from the

Natural Science).

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History of Ergonomics - tools

Tools designed

for the user

Human hand

Strengh

Range of motion1 600 BC

2 000 AC

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History of Ergonomics – ancient Greece

Ancient Greece (5th

century BC) used

ergonomic principles

in the design of their

tools, jobs, and

workplaces

Hippocrates –

description of how a

surgeon's workplace

should be designed

and how the tools he

uses should be

arranged

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https://upload.wikimedia.org/wikipedia/comm

ons/thumb/f/f8/Ancientgreek_surgical.jpg/600

px-Ancientgreek_surgical.jpg

History of Ergonomics – XVII century

Bernardino Ramazzini (1633-1714)

Studied medicine and focus on diseases

suffered by workers

Author of De Morbis Artificum Diatriba

(Diseases of Workers)

Was aware of repetitive movement

injuries to workers

Clerks

Cobblers and tailors

Porters

Conclusions: the physical workload type

determines injury risk

Father of occupational medicine (Stack

et al. 2016)

https://wellcomeimages.org/indexplus/obf_images

/b4/3b/e44fb954f8c670194bc164917600.jpg

Frederick Taylor (1856-1915) Research for

work capability Work time

measurement Scientific

method of work organizing

Scientific management 1903 – Shop

Management 1911 – Scientific

Management

History of Ergonomics – XIX century

"Testing Engineer at Work." A man, possibly Frederick

W. Taylor, sits in a chair observing an engineer at work

at Midvale Steel Company, ca, 1885

The Kheel Center for Labor-Management, www.ilr.cornell.edu/library/kheel

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The research of shoveling

Purpose:

Load optimization

Shovel shape optimization

Method: searching for the best relation

between load weight and workers’ capacity

The research of shoveling

Shovel type related

to shoveled material

Optimal load 10 kg±

1 kg

Tools supplied by

employer

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History of Ergonomics – XIX century

Frank and Lillian Gilbreth „Time and Motion Studies".

Improving efficiency by eliminating unnecessary

steps and actions

Chronocyclography

Example: bricklaying

"Chronocyclegraph of Roger [Howey?] champion golfer."

The Kheel Center for Labor-Management www.ilr.cornell.edu/library/kheel

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Frank and Lillian Gilbreth „Time and

Motion Studies".

Improving efficiency by eliminating unnecessary

steps and actions

Chronocyclography

Example: bricklaying

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Therblig – classification of work

activities

Ninjatacoshell [CC BY-SA 3.0

(https://creativecommons.org/licenses/by-sa/3.0)]

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Motion analysis

reduction the number

of motions in

bricklaying from 18 to

4.5, allowing

bricklayers to increase

their productivity from

120 to 350 bricks per

hour

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Worker posture analysis

The work must be

brought to the man

waist-high. No worker

must ever have to

stoop to atach a

wheel, a bolt, a screw

or anything else to the

moving chassis

/Henry Ford about Ford

T at assembly line/

www.corporate.ford.com/articles/history/100-years-

moving-assembly-line.html

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History of Ergonomics – XX century World War II: development of new and complex

machines and weaponry

New demands on operators' cognition

Key success factors:

hand-eye coordination of the machine's operator

decision-making

attention

situational awareness

Pilot error reduction – Chapanis work on more

logical and differentiable controls in airplane

cockpit

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Systematic investigations of toleration limits of

physical, mental and environment overload

Rational principles of device design

International organisations:

1949 – Ergonomic Society (Great Britain)

1977 – Polish Ergonomic Society - Polskie

Towarzystwo Ergonomiczne (PTErg)

History of Ergonomics –

contemprorary times

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Ergonomics

Science about relation between human beings

and their work environment.

/Kenneth Frank Hywel Murrell 1949/

Ergonomics

Ergonomics is the science of designing the

workplace environment to fit the user

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Ergonomics

Body of knowledge about human abilities,

limitations and characteristics that are relevant

to design. Ergonomic design is the application of

this knowledge to the design of tools, mahines,

systems, tasks, jobs, and environment for

safe, comfortable and effective human use.

/Board of Certification for Professional

Ergonomists - BCPE /

Ergonomics

Human Machine

Work Environment

Utmost Goal: “Humanization” of Work

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Ergon – work

Nomos – law

Ergonomics = laws of work

Science of fitting workplace conditions and

job demands to the capabilities of the

working population

Ergonomic study areas

WORKERS - what they bring to the job

TOOLS - what they bring to the worker

TASKS - what the worker must do

ENVIRONMENT- the conditions

surrounding the worker and the tool

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The ToolThe Task

The Work

Station and

Environment

The User

/Operator

Ergonomic focus

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Ergonomics

Ergonomics is the science of improving

employee performance and well-being in relation

to the

job tasks

equipment,

the environment.

Ergonomics is a continuous improvement effort

to design the workplace for what people do well,

and design against what people don’t do well.

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Ergonomics

Ergonomics (or human factors) is the scientific

discipline concerned with the understanding

of interactions among humans and other

elements of a system, and the profession that

applies theory, principles, data and methods

to design in order to optimize human well-

being and overall system performance.

/IEA - International Ergonomics Association (2000)/

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What can be ergonomic?

Machines

Devices

Tools

Rooms

Software

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What can be ergonomic?

Conditions

Work

Life

Sport

Rest

Homes

Products - cars, toys, furniture

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What does it mean?

Fitted to user

No negative effects

Minimal biological cost

Gives satisfaction to user

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Human – Millieu system

Human

Physical features

•Anatomy

•Body measures

•Physiology

•Stamina

Psychological

features

•memory

•perception

•attention

Millieu

Material

environment

•microclimate

• lighting

•noise

Technical devices

•Work tools

•Transport

•Supporting

equipment

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Sources or ergonomic knowledge

Human Being

Anthropometry

Anatomy

Biomechanics

Kinesiology

Physiology

Psychology

Sociology

Organisation

Work organisation

Quality management

Marketing

Technics

Mechanical engineering

Industrial design

Steering

Benefits of Ergonomics

Decreased injury risk

Decreased

mistakes/rework

Decreased turnover

Decreased lost work

days (absence)

Increased efficiency

Increased

productivity

Improved morale

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Costs

Economical

Direct: lost production, medical costs,

insurance

Indirect i.e. inefficiency costs of

restricted work, hiring and training

replacement, overtime because of injury

statistics of Work-Related

Musculoskeletal Disorder (WMSD)

Moral loss

Biological – ability of sustaining

different kind of load (physical,

psychical and environmental)

http://www.ecoscope.com/iceberg/

Conclusion: Physical factors are main problem

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Percentage of workers reporting that they are exposed to

different physical risk factors at their work at least a

quarter of the time, EU-28, 2005, 2010 and 2015(EU-OSHA

2019)

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Conclusion: MSD are main problem

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Percentage of workers reporting work-related health

problem, by type of problem, EU-27, 2013 (EU-OSHA

2019)

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Percentage of workers reporting different

musculoskeletal disorders in the past 12 months, EU-

28, 2010 and 2015 (EU-OSHA 2019)

Conclusion: we notice progres, but too slow EU-OSHA

2020-22 campaign focuses on the prevention of WMSDs

Waehrer, G. M., Dong, X. S., Miller, T., Haile, E., & Men, Y. (2007).

Costs of occupational injuries in construction in the United States. Accident Analysis & Prevention, 39(6), 1258-1266.

Estimated prevalence rates of self-

reported WRMSDs in Great Britain, by

how caused or made worse by work

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http://www.hse.gov.uk/statistics/causdis/msd.pdf, 2019

Number of cases of WRMSDs by

anatomical site 2013-2015 in Great

Britain

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http://www.hse.gov.uk/statistics/causdis/msd.pdf, 2019

Percentage share of factors related to

working environment (Polish Central

Statistical Office, 2012)

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Ergonomics

Ergonomics is the science of designing the

workplace environment to fit the user

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Ergonomics

Human Machine

Work Environment

Utmost Goal: “Humanization” of Work

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Ergonomics

Ergonomics is the science of improving

employee performance and well-being in relation

to the

job tasks

equipment,

the environment.

Ergonomics is a continuous improvement effort

to design the workplace for what people do well,

and design against what people don’t do well.

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The division of ergonomics

Mikroergonomics

perception

antropometrics

human – device systems

cognitive and decision making

processes

Human Computer Interaction (HCI)

Macroergonomics – organizations as

complex systems

II generation

I generation

III generation

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The division of ergonomics

Physical ergonomics - human anatomical,

anthropometric, physiological and bio mechanical

characteristics as they relate to physical activity

Cognitive ergonomics - mental processes, such as

perception, memory, reasoning, and motor

response, as they affect interactions among

humans and other elements of a system

Organizational ergonomics - optimization of socio

technical systems, including their organizational

structures, policies, and processes

Physical ergonomics

Biomechanical overload

Layout design

Steering and control design

Workstation design

Work environment

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Cognitive ergonomics

mental workload

decision-making

human-computer interaction

human reliability

work stress

Work training

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Organizational ergonomics

Communication

Crew resource management

Work design

Teamwork

Community ergonomics

Cooperative work

Virtual organizations

Quality management

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The division of ergonomics

Corrective ergonomics – the improvement of

the existing state

Conceptive ergonomics – proper design

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Corrective ergonomics efects

24% efficiency increase among users of ergonomic

workstations

Research of Marvin Daindoff dla NIOSH (The National

Institute for Occupational Safety and Health)

20% efficiency increase after buying the ergonomic

furniture

Illinois University,1990

Personnel turnover decrease from 35% to 2%

Regional Bell Operating Company

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Ergonomic design

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Human – Millieu system

Human

Physical features

•Anatomy

•Body measures

•Physiology

•Stamina

Psychological

features

•memory

•perception

•attention

Millieu

Material

environment

•microclimate

• lighting

•noise

Technical devices

•Work tools

•Transport

•Supporting

equipment

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First approach - Universal Design

Designing products, buildings and exterior

spaced to be usable by all people to the

greatest extend possible

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7 UD principles

1. Equitable use – avoid segregating or stigmatizing

2. Flexibility in use - i.e.right and left hand

3. Simple and intuitive use – consistent with expectation

4. Perceptible information – redundant, contrast and

compatible

5. Tollerance for errors – warnings and restricted access

to most hasardous elements

6. Low physical effort – fatigue minimizing

7. Size and space for approach and use – good approach,

reach and manipulation regardless to user body size,

posture or mobility

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Homework

An example of universal design with

explanation

Pdf or ppt file, maximum 3 slides

Your name in the presentation title

Deadline: 1.03.2020

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Ergonomic design

Designing for majority

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Stages of ergonomic design

1. Body measures

2. Biomechanical activity

3. User – workstation relations

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Body measures

Most important for design

Human body is the main part of every workstation

Variety of body measures

In population

Purpose: designing for everyone

Standard distribution

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Restraining values – 5 and 95 percentile

Mode

MedianMean

Men

Women

Average

Adult

90% of population

Height Probability Distribution

for US men and women

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National Health Statistics Reports, Anthropometric Reference Data for Children and

Adults: United States, 2003–2006

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Centile models

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Simplex limitations

Minimal - reach

Maximal

Heights (headroom)

Safety measures

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Duplex limitations

User population

Adjustment

Main aim Design examplesExamples of

measurements

Users should

accommodate

Easy reach Vehicle dashboards,

Shelving

Arm length,

Shoulder height

Smallest user: 5th

percentile

Adequate

clearance to avoid

contact or trapping

Manholes,

Cinema seats

Shoulder or hip width,

Thigh length

Largest user: 95th

percentile

A good match

between the user

and product

Seats,

Cycle helmets,

Pushchairs

Knee-floor height, Head

circumference, Weight

Maximum range: 5th

to 95th percentile

A comfortable and

safe posture

Lawnmowers,

Monitor positions,

Worksurface heights

Elbow height,

Sitting eye height,

Elbow height (sitting or

standing?)

Maximum range: 5th

to 95th percentile

Easy operation Screw bottle tops,

Door handles,

Light switches

Grip strength,

Hand width,

Height

Smallest or weakest

user: 5th percentile

To ensure that an

item can't be

reached or

operated

Machine guarding mesh,

Distance of railings from

hazard

Finger width

Arm length

Smallest user: 5th

percentile

Largest user: 95th

percentile68

Three approaches

1. Design for adjustable ranges – particularly

when health and safety issues are involved

(driving a car, computer workstation)

2. Design for extremes – maximum or

minimum values

3. Design for average users – 50 percentile

figures

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2. Biomechanical and

physiological features

Give me a place to stand

on, and I will move the

Earth.

Archimedes

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Biomechanical and physiological

features

Physiological features

Senses activity

Fatigue

Biomechanical agility

Permissible spread of joint mobility

Prompted forces and torques

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Visual field

1. Often vision without

head and torso

movements

2. Observation and

manipulation with

bend head

3. Rare observations

4. Rare observations

with head and torso

leaned back

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Arm and forearm surface area

Normal reach

Maximal reach

Elbow level Shoulder level

Approximated data for design

A – normal reach

B – maximal reach

C – two-handed work area

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3. Relation analysis

User - device

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3. Relation analysis

Analysis of all activities

Equipment choice

Working posture choice

Bondable points

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Equipment choice

Task

Layout criteria by McCormick

Importance

Frequency of use

Sequence of use

Similar functionality

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Factors influencing working height

Worker’s measures

Task features

Precision

Used force

Object size

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Working height for standing posture

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Bondable points

"We bear in mind that the object we are working on is

going to be ridden in, sat upon, looked at, talked into,

activated, operated, or in some other way used by

people. If the point of contact between the product and

the people becomes a point of friction, then the industrial

designer has failed.

On the other hand, if people are made safer, more

efficient, more comfortable - or just plain happier - by

contact with the product, then the designer has

succeeded."

Henry Dreyfuss

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Satisfaction

Fitted to user

Safe

Functional

Pouring

Boiling

Cleaning

Nice to see….

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Six Pillars of Ergonomic Design

1. User Orientation: Design andapplication of tools, procedures, andsystems must be user-oriented, ratherthan just “task” oriented

2. Diversity: Recognition of diversity inhuman capabilities and limitations,rather than “stereotyping”workers/users

3. Effect on Humans: Tools, procedures,and systems influence human behaviourand well-being

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Six Pillars of Ergonomic Design

4. Objective Data: Empirical information and

evaluation is key in design process, rather

than just use of “common sense”

5. Scientific Method: test and retest

hypothesis with real data, rather than

“anecdotal” evidence or “good estimates”

6. Systems: object, procedures, environments,

and people are interconnected, affect one

another, and do not exist in “isolation”

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Grandjean layout principles

1. For standing people, the appropriate table

height depends on kind of work

2. For seated people, the appropriate table

height depends on chair height

3. Tools, materials and controls should be

located close to the point of use

4. There should be a definite and fixed place

for all tools and materials

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1. For standing people, the appropriate

table height depends on kind of work

For high precision work, tables should be up to 10

cm higher than elbow height

For heavy work as much as 20 cm below elbow

height

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2. For seated people, the appropriate

table height depends on chair height

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3. Tools, materials and controls should

be located close to the point of use

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4. There should be a definite and

fixed place for all tools and materials

Gravity feed bins

and containers

Materials arranged

in the sequence of

use

5S

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Design of tools

Basic reference point –

human hand

Dymorphism on size and

forces

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1. Fit the tool for the body size of

user

Hand tools are frequently designed for the

"average male" hand

Grip diameter = 20% of hand length equals

Modifying handle grip

Use a replacement handle, if available.

If the handle is too small, add a sleeve or

cushion (or duct tape)

If a handle is too large, sand it down to a

smaller diameter if it is made out of wood.92

2. Avoid nonneutral hand movements

Push or pull in the

direction of the

forearm

Keep the wrist

straight

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3. Avoid static overload

Avoid pressure points ans pinch points

Avoid vibrations transmission

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4. Do not operate tools frequently

and forcefully by hand

Avoid repetitive work

Automatization

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5. Provide good coupling between

hand and handle

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