pdf ergonomi

By MIRTA DWI RAHMAH

MAN – MACHINE –ENVIRONMENT

Work Environment The physical aspects of a workplace environment can have a direct impact on the productivity, health and safety, comfort, concentration, job satisfaction and morale of the people within it. Important factors in the work environment that should be considered include building design and age, workplace layout, workstation set-up, furniture and equipment design and quality, space, temperature, ventilation, lighting, noise, vibration, radiation, air quality. Ergonomics is the study of the relationship between people, the equipment they use and the physical environment in which they work. Applying ergonomic principles to the design, modification and maintenance of workplace environments, has a benefit on people’s work performance and short- and long-term health and safety.

Work system Elements

HUMAN -‐  Physical -‐  Mental -‐  Cogni?ve

ENVIRONMENT -‐  Noise -‐  Temperature -‐  Vibra?on -‐  Ligh?ng

MACHINE -‐  Process

-‐  Equipment -‐  Task -‐  Tool

! the productivity, health and safety, comfort, concentration, job satisfaction and morale of the people

Ergonomics …is the scien;fic discipline concerned with the understanding of interac?ons among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to op;mize human well-‐being and overall system performance. …is concerned with the "fit" between the user, equipment and their environments. It takes account of the user's capabili;es and limita;ons in seeking to ensure that tasks, func;ons, informa;on and the environment suit each user.

The Interna;onal Ergonomics Associa;on

Ergonomics or biomechanics

Ergonomics is described as the study of

rela?onship between man and his working

environment. It also deals with man-‐machine

rela?onship

•  Design of physical devices -‐ display panels, controls i.e. user friendly

•  Work environment 1) Temperature and humidity 2) Noise 3) Light or illumina;on 4) Color 5) Vibra;on •  Ability and mo;va;on of operator

Efficiency of Man Machine System is affected by the following…

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Working environment

o  Physical factors: effect of illumina;on, temperature, noise and vibra;on

o  Chemical factors: chemical substance, gas, vapor, dust

o Biological factors: infec;ons caused by bacteria, viruses, fungi and worms

o  Physiological factors: aZtudes and ways of working, the determina;on of working hours and breaks, shi[ work, over;me

o  Psychological factors: the atmosphere of the workplace, the rela;onship between workers

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Temperature and humidity

•  Efficiency of employees performing physical works decreases when temperature increases beyond 80 degree Fahrenheit

•  Workers not performing physical works tend to become less efficient at temperatures above 90 degrees Fahrenheit

•  During cold season, the work environment should have hea;ng facility

•  Air condi;oning office environment reduces fa;gue and errors

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•  High humidity level also affects the performance of the workers

•  If humidity is very high, then temperature above 90 degrees Fahrenheit can be s;fling

•  In less humid condi;ons workers can endure more heat

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•  A cold dry environment is much more comfortable than under condi;ons of high humidity

•  In produc;on areas it is difficult to control humidity but not so in office areas

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Temperature

o  Inner body temperature ! 37°C " ‘Equilibrium’ " Heat Produc;on ! get from body metabolism

" Heat Loss ! radia;on, evapora;on

o Environmental temperature

" Hot " Cold

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Common warning signs:

Extreme Temperatures

o  Dehydra;on o  Compromised ;ssues

•  Muscle cramps

•  Restless leg syndrome

o  Poor circula;on

Heat Stroke

o  Mainly caused by changes in the body temperature.

o  Excessive physical work can be a major cause of heat stress, especially when there is a disrup;on body thermoregula;on capabili;es

o  Younger people ! hard worker, military training, athlete.

o  Preven;on ! sufficient ;me to rest, the adequacy of body fluids, etc.

Hypothermia

•  Poten;ally dangerous drop in body temperature, usually caused by prolonged exposure to cold temperatures.

•  Extreme environment temperature can also lead to hypothermia depending on a person’s age, body mass, body fat, overall health and length of ;me exposed to cold temperatures

•  Below 35°C ! improve probability of death

Below 30°C ! sudden death (heart failure)

Other effects of low temperature

o Performance related (behavior disrup;on)

" Motor performance: # tac;le sensi;vity # manual performance

" Cogni;ve performance: # tracking # reac;on ;me # complex behavior

Noise

•  Is the result of varia;ons in air pressure •  May result from human speech, machine opera;on, vibra;ons, and reverbera;on

•  Employees have the ability to adapt to noisy environment within reasonable limits

•  Higher noise levels are annoying and painful

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Noise

•  Exposing employees to higher noise levels may impair their power of hearing

•  Could be reduced by replacing or adjus;ng moving parts, frequent lubrica;on, maintenance, installing special devices – carpets, curtains

•  Beker to isolate noisy machines in separate buildings

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Noise is unwanted sound. It is a pollutant and a hazard to human health and hearing. Noise in our environment affects physical health. Noise also has psychological and social implica;ons and affects our well being and quality of life. Noise can be reduced by lubrica;on of machine, drapes and ceiling ;les are used to absorb unwanted sound and eliminate echoes and mufflers are used to reduce noise.

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Noise

Painful •  150 dB = rock music peak •  140 dB = firearms, air raid siren, jet engine •  130 dB = jackhammer •  120 dB = jet plane take-‐off, amplified rock music at 4-‐6 [., car stereo, band

prac;ce Extremely Loud •  110 dB = rock music, model airplane •  106 dB = ;mpani and bass drum rolls •  100 dB = snowmobile, chain saw, pneuma;c drill •  90 dB = lawnmower, shop tools, truck traffic, subway Very Loud •  80 dB = alarm clock, busy street •  70 dB = busy traffic, vacuum cleaner •  60 dB = conversa;on, dishwasher Moderate •  50 dB = moderate rainfall •  40 dB = quiet room Faint •  30 dB = whisper, quiet library

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Noise

Noise o  Excessive noise may increase staff stress and fa;gue. General

noise may be reduced by floor carpe;ng and by loca;ng office areas away from sources of external noise. The recommended decibel range for office work is 55 to 65 dBA.

o  Hard surfaces such as glass walls or white boards will act to increase the reflec;on of noise.

o  Telephone or other conversa;ons can be distrac;ng in open plan offices. Sound absorbing barriers may be considered if such noise is a problem.

o  Some office groups follow their own "low noise rules". o  Some office machines have high noise levels. Supervisors

should ensure their loca;on, pakerns and vicinity to staff are such as to prevent problems.

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Illumina?on

o  Light is energy in the form of electromagne;c waves are invisible to the 380-‐750 nm wavelength. Packets of light called a spectrum then visually perceived by the senses of sight as color

o  Ligh;ng is one of the factors to get the state of a safe and comfortable environment and is closely related to human produc;vity. Good ligh;ng allows people to be able to see objects clearly and quickly doing

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Illumina?on

Source of ligh;ng " Natural: sunlight " Ar;ficial: Required when natural ligh;ng is insufficient

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Illumina?on

•  Provide adequate light to perform •  Various ligh;ng intensi;es have been recommended for different types of jobs

•  Lower illumina;on levels cause fa;gue and error

•  Over illumina;on is a strain to the eyes and leads to errors

•  Glare is another problem

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Ilumination ( lumen/m2 )

Luminance (foot lambert)

Brightness

Brain

Illumina?on

•  Light intensity •  Reflectance •  Glare

Illumina?on

GENERAL REQUIREMENTS OF ARTIFICIAL LIGHTING.-‐ 1. Sufficient illumina;on should be provided for each workman irrespec;ve of

his posi;on on the working space. 2. The lamps should be properly selected and so installed as to avoid or

minimize strain on the eyes of the workmen. The type and size of lamp should be adapted to the par;cular ceiling height and class of work in ques;on.

3. The lamps should be operated from sources of supply which will insure con;nuity of service and steadiness of light.

4. Adequate illumina;on should be provided from overhead lamps so that sharp shadows may be prevented as much as possible, and in such measure that individual lamps close to the work may be unnecessary except in special cases.

5. In addi;on to the illumina;on provided by overhead lamps, individual lamps should be placed close to the work if they are absolutely necessary, and in such cases the lamps should be provided with suitable opaque reflectors.

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Illumina?on

Ligh?ng Op?ons

SOURCE: American Journal of Public Health

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General Office Ligh?ng

"  In all working environments the ligh;ng situa;on needs to be

considered. "  Illumina;on is measured in units of LUX -‐ lumens per square

meter "  "Ordinary" visual tasks should be in range 300 to 400 lux [320

lux (task) and 160 lux (Background)]. "  Op;ons for adjus;ng ligh;ng include(eg: computer) "  Posi;oning of the monitor to the side of window light and/or

in between overhead light sources. "  "An;-‐glare" Screen Filters-‐ Where all other efforts to correct

ligh;ng have not succeeded, use of a screen filter may be necessary.

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Visual Work CS 31

Aplication ISO (lux)

Example BS 8206 (lux)

General lighting for area used infrequently or having simple visual demands 20—200 lux

Public area with dark surroundings

20-50

Area for occational access

50—100 Walkways, cable tunnels 50

Rooms not used for continuous work

100—200 Storage areas, entrance hall 100

General lighting for working interior 200—2.000 lux

Task with limited visual requirements

200—500 Rough machining, lecture theatres

300

Task with normal visual requirements

500—1.000 Medium machining, office 500

Tasks with special visual requirements

1.000—2.000 Hand engraving, drawing office

750

Additional lighting for visually exacting task 2.000—20.000 lux

Very prolonged exacting visual tasks

2.000—7.500 Electronic or watch assembly

1.000

Exceptionally exacting visual tasks

5.000—10.000 Micro-electronic assembly 2.000

Very special visual tasks

10.000—20.000 Surgical operations

Recommended Ranges of Ilumina?on

Color

•  Colors used in working environment affect the performance

•  Light colors are advisable for walls and ceiling •  Colors have a remarkable effect on human behavior

•  Green and Blue are cool colors •  Red and Orange are warm colors

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Color •  Dull colors are used in machines to reduce glare

•  Light green is the favorite color for machine manufacturers as it is akrac;ve and relaxing

•  Color is also used for plant safety and coding •  Fire ex;nguishers are painted red •  Poten;al danger areas are outlined in yellow •  Color coding helps to dis;nguish between similar devices – hot water value is painted red, cold water valve is painted blue

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Vibra?on

Can lead to injury when you are:

"  Using reciproca;ng tools

"  Using grinding or impact tools

"  Using vibra;ng tools

"  Working in or on motorized vehicles

•  Vibra?on refers to mechanical oscilla;ons about an equilibrium point. The oscilla;ons may be periodic such as the mo;on of a pendulum or random such as the movement of a ;re on a gravel road.

•  vibra;on is undesirable, was;ng energy and crea;ng unwanted sound – noise. For example, the vibra;on mo;ons of engines, electric motors, or any mechanical device in opera;on are typically unwanted. Such vibra;ons can be caused by imbalances in the rota;ng parts, uneven fric;on, the meshing of gear teeth, etc. Careful designs usually minimize unwanted vibra;ons.

•  Vibra;ons can be reduced by machine balancing, machine over hauling and material selec;on.

•  Machine casing, ear plugs, absorp;on materials and dampers have to be provided to reduce vibra;on.

•  Vibra;on can be source of fa;gue.

•  The most serious effect of vibra;on, especially in the case of machinery, is that sufficiently high alterna;ng stresses can produce fa;gue failure in machine and structural parts. Less serious effects include increased wear of parts, general malfunc;oning of apparatus, and the propaga;on of vibra;on through founda;ons and buildings to loca;ons where the vibra;on of its acous;c realiza;on is intolerable either for human comfort or for the successful opera;on of sensi;ve measuring equipment.

Vibra?on

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Vibra?on

o Have serious influences to human body " Visual percep;on " Psychomotor performance " Musculature " Blood circula;on " Respiratory " Nervous system

REFFERENCES

Person-‐Centred Ergonomics: A Brantonian View Of Human Factors edited by D J Osbourne, F. Leal, R Saran, P Shipley, T Stewart

Ergonomic models of anthropometry, human biomechanics, and operator ... By K. H. E. Kroemer, Thomas B. Sheridan, Na;onal Research Council (U.S.). Commikee on Human

Factors, Na;onal Research Council (U.S.). Commission on Behavioral and Social Sciences and Educa;on

A Guide to Human Factors and Ergonomics (2005) by Mar;n Helander.

The Occupa?onal Ergonomics Handbook (1998) Edited by Waldemar Karwowski, William S. Marras.

CCOHS, Working in the cold temperatures

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