ergonomics designs and considerations

2.  Ergonomics is concerned primarily with the
physiological aspects of job design that is with the
human body and how it fits into its surroundings.
 Ergonomics sometimes referred to as “human
factors engineering” or just “human factors”
 It involves 2 aspects:
1.How the person interface with the physical aspect
of his or her workplace
2.How a person interfaces with the environmental
conditions in his or her immediate working area.

3. Both of these aspects are linked by 2 common idea that
permeate ergonomics approach to job design
 There must be a fit between people and the jobs they
do.
 The second idea is that of data collection. It takes a
scientific approach and tries to collect data to indicate
how people react under different job design
conditions and tries to find the best set of condition.

4.  In many operations new demand, technologies
and work methods have refocused attention
on the way people interface with the physical
parts of their jobs.
 To understand how workplace affect
performance, fatigue,physical strain and injury
are all part of the ergonomics approach to job
design.

5.  This aspect is related to the peoples size,
shape and other physical abilities, for
example left-handedness.
 For example design of an assembly task
should be governed partly by the size and
strength of the operator who do the job.
 The data which ergonomists use when doing
this is called anthropometric data.

6. 5th
percentile
50th
percentile
95th
percentile
Std. dev
Stature(heig
ht)
149.5/161.8 160.5/173.6 171.3/184.4 6.6/6.9
Eye height 138.3/151.1 148.9/162.4 159.3/172.7 6.4/6.6
Shoulder
height
121.1/132.3 131.1/142.8 141.9/152.4 6.3/6.1
Elbow height 93.6/100 101.2/109.9 108.8/119 4.6/5.8
Height,
sitting
78.6/84.2 85.0/90.6 90.7/96.7 3.5/3.7
Eye height,
sitting
67.5/72.6 73.3/78.6 78.5/84.4 3.3/3.6
Shoulder
height,
sitting
49.2/52.7 55.7/59.4 61.7/65.8 3.84/4

7.  It is the range of capabilities taken into
consideration
 Usually expressed in percentiles
 When this principle is applied to other
dimensions of the body, for example arm
length.it can be used to design work
areas.

8.  It is concerned with the way in which people’s
sensory capabilities are engaged when
interfacing with their workplace.
 This neurological aspect of job design include
sight, feel, sound which the workplace
displays in order to give information to the
operator and the way in which operator can
transmit instructions back to the workplace.

9.  The workplace is usually some kind of
machine or process technology.
 The interface between the machine and
operator involves:
display of information from the machine to
operator and
manipulation of controls by the operator in
communicating to the machine.

10.  The immediate environment in which
jobs take place can influence the way
they are performed.
 The works are influenced by the working
conditions which are too hot or too cold,
insufficiently illuminated or glaringly
bright, excessively noisy or irritatingly
silent.

11. Some general points regarding working temperature
which provide guidance to job designers include:
 Comfortable temperature range will depend on
the type of work being carried out-lighter work
requiring higher temperature than heavier
work
 The effectiveness of people at performing
vigilance tasks reduces at temperature above
29 degree ;equivalent temperature for people
performing light manual task is little lower

12.  The chances of accidents occurring
increase at temperatures which are above
or below the comfortable range for the
work involved
 The intensity of lighting vary with the
nature of job
 Example surgery requires very high
levels of illumination.

13. Activity Illumiance (lx)
Normal activities in the home,
general heating
50
Furnace rooms in glass factory 150
General office work 500
Motor vehicle assembly 500
Proof reading 750
Color matching in paint factory 1000
Electronic assembly 1000
Close inspection of knitwear 1500
Watch making and fine jewellery
manufacture
3000
Surgery, local lighting 10 000-50 000

14. Noise induced hearing loss is well-documented
consequence of working environments where noise is
not kept below safe limits.
 High noise level also affect work performance
 Intermittent and unpredictable noises are more
disruptive than steady state noise at the same level.
 High frequency noise usually produces more
interference with more performance than low-
frequency noise
 Noise affect the quality of work

15. Noise Decibels[dB}
Quite speech 40
Light traffic at 25 meters 50
Large busy office 60
Busy street ,heavy traffic 70
Pneumatic drill at 20 meters 80
Textile factory 90
Circular saw-close work 100
Riveting machine-close work 110
Jet aircraft taking off at 100 meters 120

16. Ergonomics is increasingly applied in the office.
European Union directives on working with display
screen equipment require organisations to:
 Assess all work stations to reduce the risk inherent in
their use
 Make sure that all work stations meet specific
requirements
 Plan work times to all breaks and changes in activity
 Provide information and training for users
 Test the eyesight of users if they request it.