industrial hygiene part2 paper v

7/27/2019 Industrial Hygiene Part2 Paper V

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Chemical Hazards - arise from excessive air born concentrations of mists, vapours, gases or

solids that are in the from of dusts or fumes. In addition to the hazard of inhalation, many of

these materials my act as irritants or may be toxic by absorption through the skin.

Solid - Packing density high, degree of freedom restricted. After breaking, surface area &

volume is more.

6cm2 are breaks 6m2 area. It means more active centre for toxicity.Liquid - Packing density low, degree of freedom more than solid.

Gas - Indefinite expansion, very high molecular mobility, liquefied with decrease temperature

and increased pressure. It can diffuse.

Vapours - Evaporation product of the substance which are liquid at normal temperature. Liq-

uid fide with either decrease temperature or increases pressure.

Dusts - Generated with mechanical process: drilling, pulverising, grinding

> 10 micron - suspended in air

< 3 mircron - injurious to health

Fumes - Generated with combustion or sublimation process.

Pb Ho Pb vapours - condensed with oxidation Pb fume (PbO) - Metal Fume

Smoke - Generated from carbonaceous material of a matter this is organic in nature.

Mist - Liquid droplets suspended in air, Splashing, atomisation, electroplating. Placed in steady

step for some time it comes to Fog step.

Physical Hazards - Include excessive levels of electromagnetic and ionising, noise, vibration,

and extremes of temperature and pressure.

Biological Hazards - include insects, molds, fungi and bacterial contamination including such

sanitation and house keeping items as potable water, removal of industrial waste and sew-

age, food handling and personal cleanliness.

Ergonomic Harzards - include improperly designed tools or work areas. Improper lifting or

reaching poor visual conditions, are repeated motions in an awkward position may be respon-

sible for accidents in the occupational environment.

Particulate Matter

Solid Phase Liquid Phase

Dust Fume Smoke Mist Fog

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and vapours, these are asphyxiation, irritation of the respiratory organs, and narcosis.

Other responses which are more typically chronic in nature include damage to lings, to blood

nervous system, liver, kidneys, bones, skin etc. a few examples are cited-

a) Inhalation of dust containing silica, arsine, lead may produce silicosis and changes in

blood, organic phosphates destroy the enzyme, cholinesterase, which is present in the

red blood cells.

b) Carbon disulfide and some of the halogenated hydrocarbons have a cumulative effectupon the nervous system. Chronic mercury and manganese poisonings usually in-

volve the nervous system.

c) Injury to liver and kidney may be caused by carbon tetrachloride.

d) Chronic poisoning from yellow phosphorus and fluorine may cause serious damage to

bone structure. Cancer frequently develops in bones in which radium is deposited.

e) Skin affliction n the form of dermatitis amy be attributed to the skin absorption of

tetramethyllead, epoxy resins, cutting oils, etc. skin cancer may be caused by long

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continued contact with certain constituents of coal tar and shale oil.

f) Bladder tumours may be caused when chemical carcinogens, such as beta napthylamine

and benzidine are inhaled over a considerable time. Radioactive substances also pro-

duce tumours.

Use of Special Diagnostic Tests for Early Detection of Exposure and Ailments

Related to Occupations

The toxic substances may affect some particular parts or systems in the body bring about

changes in those areas. This effect can be measured by special investigation, such as bio-

chemical tests, pulmonary function tests, psychological tests, radiography and other investi-

gations. However, the usefulness of these tests are limited to exposure to only certain toxic

agents. The biochemical examinations are restricted primarily to blood and urine analyess.

Examination of blood for car boxy hemoglobin is a common method of determining recent

carbon monoxide exposure. The lead content of blood is also an useful index for finding out

lead exposure. Analysis of urine for toxic elements, such as lead, mercury, fluorides, etc. is

the most widely applicable biochemical tests for the evaluation of exposure to these sub-stances. Estimations of certain products, such as ALA and coproporphyrin in the urine are

useful indications of absorption of lead.

The presence of toxic material in the blood, or urine doses not necessarily implies poisoning

Analysis of blood or urine of apparently healthy workers for toxic ingredients is primarily for

the purpose of detecting excessive exposure to the poison and is not intended otherwise. On

the other hand, if an individual shows signs and symptoms of lead poisoning, the presence of

an abnormally high lead concentration in the blood or urine of the individual confirms the

diagnosis Another aspect of these tests is to detect early stages of poisoning before clinical

symptoms ordinarily appear. Thus blood changes caused by benzene are detectable beforesubjective symptoms are in evidence. A reduction in the cholinesterase activity of the blood is

reliable indicator of organic phosphate poisoning. X-ray of the chest and lung function tests

are useful procedures in environmental lung disorders, such as silicosis and asbestosis. Cy-

tology of urine can help in early detection of bladder cancer. Pure tone audiometry is useful ,

not only for detection of hearing impairment at an early stage, but also for evaluation of the

effectiveness of noise control measures, where such measures have been adopted.

Biological Monitoring - Already covered in section - I (Industrial Hygiene)

EVALUATION OF INDUSTRIAL INJURIES

Evaluation of injuries is done for the purpose of assessing the compensation to the effected

worker. For this we have Workmens Compensation Act. This is not interested merely in

physical disability because compensation cannot be paid for any physical disability unless

there is loss of earning capacity. The loss of earning capacity is proportional to the loss of

function of the affected part of the body.

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Spine

Lumber region 50 to 100%

Dorsal region 25 to 50%

Cervical region 20 to 30%

Fracture 5 to 10%

ThoraxFracture of one rib usually no disability.

3-4 ribs 5 to 10%

Sternum 5 to 10%

Head injuries

Disability evaluation depends upon after effects.

Eyes

Loss of vision of one eye 30%Loss of vision of both eye 100%

Ear

Total loss of hearing is 25%

Loss of haring of one ear is 15% voice 25 to 50%

OCCUPATIONAL HEALTH MANAGEMENT SERVICES

Occupational health management works for service, humanity. The goals & objectives of health

management are :> Care - preventive, curative, rehabilitative

> Custody - short term, long term

> Training

> Research

In industry, the worker is more important than the machine which he operates. To safeguard

the health, safety and welfare of the worker, factory laws have been enacted in every country.

The Conventions and Recommendations famed by the ILO provide guidelines to the member

countries in the development of legal provisions for protection of workers health.

These international instruments relate to the matters such as :

Hours of work;

Night work;

Weekly rest;

Paid leave;

Guidelines on protection of health of workers, setting up of occupational health ser-

vice, carrying of heavy weight etc.

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PHYSICAL HAZARDS

Physical hazards include excessive levels of noise, radiation, and extremes of temperature

and pressure.

Noise defined as unwanted sound is a form of vibration that may be conducted through

solid, liquid or gases. Vibration is caused because of high intensive and low frequency sound

level and resonance effect. Sound levels are measured in dicibel (dB). The audible range isbetween 16 and 20,000 Hertz (Hz), below 16 Hz. the sound is sub audible and above 20,000

Hz. it is ultrasonic.

Sound levels are measured by:

Weighted sound level meter

Octave band analyser

Impulse meter

And to detect the hearing loss audiometric test programmes are arranged and the test

is being carried out by a qualified & certified Otologist.

Permissible Noise Exposures

Duration per day (Hrs.) Sound Level (dB)

8 90

6 92

4 95

3 97

2 100

1.30 102

1 1051 min. 110

15 min. 115

Sound levels in decibels :

20 whisper

48 average residence

60 conversational speech

80 heavy traffic

90 safe limit for sustained noise

110 punch press, pneumatic rock drill

140 jet engine

The effects of noise on man include the following ;

Phycological effects - noise can startle, annoy and disrupt concentration , sleep or

relaxation.

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RADIATION

Alpha-particles, beta-particles, X-rays, gamma-rays and cosmic-rays are emitting ionizing

radiation. In ionizing radiation the atoms are made into ions by adding or removing one or

more electrons, these rays are much shorter but have high frequency & emit high kinetic

energy. Radio/Micro waves, Infra red/Ultra violet rays emit non-ionizing radiation. In Non-

ionizing radiation the energy is emitted or absorbed by small pulse-quanta & has low fre-

quency. Alpha/Beta particles are emitted from radioactive nuclei at high speed with high en-ergy. X-rays produced by high speed electrons striking a suitable target or vacuum tube.

Electrical potential required to accelerate electrons to generate X-rays is 15000 to 16000

volts.

The units for radiation

Frequency Hertz (Hz)

Wavelength A anstrom meter

Energy Electron volt (eV)

Possible causes & effects of ionizing & non-ionizing radiation :

Possible effect Possible Sources

Infrared radiation :

Undesirable heat gain. Flames

Increased temp in enclosed space. Solar radiation

Overheating Infrared heaters.

Skin burns Highly heated surface.

Charring of organic material Lasers.

Ionizing :

Tissue damage

Alpha-particles will barely pehetrate the dead

cells of the skin, beta-particles will go slightly

deeper and x-rays/gamma-rays go far deeper .

Degradation of electronic components.

Degradation of material strength

Inadequate containment of radioactive material

Accidental exposure of ionizing sources

Inadvetent production of rays.

Use of X-rays equipment

Nuclear reaction.

Possible effects

Microwaves :

Heating of metals and tissue by induction.

Catar act of other eye injury

Interference with operation of other electronic

equipment.

Activation of sensitive electro explosive.

Rader equipment operation.

High power and microwave equipment opera-

tion.

Other microwave operation.

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Heat exhaustion : The effects of heat exhaustion are - because of physical exertion in a hot

environment, pulse becomes weak with dizziness and profuse sweating.

Cold stress : While working in cold atmosphere there are chances of getting hypothermia in

which blood vessels get dilated and tissue freezes.

EXTREME PRESSURE

Divers operating under water and during tunneling operations the following health effects maydevelop :

> Tissue damage.

> Teeth, sinuses and ear are affected by pressure difference.

> Decompression sickness results from release of nitrogen bubbles into the circulation,

If the bubble lodge at the joint and under muscles causes severs cramps.

ILLUMINATION

Thus illumination or lighting is an important working condition not only in factories but at all

work places. Therefore it should be effective and not poor.

Effects of bad lighting are direct and manifold, because it affects our sight or visual percep-

tion. Bad light causes glare shadows, darkness. eye strain and unhealthy eyes, restricted

vision fatigue, accidents and lower output. Poor lighting requires more time to see or distin-

guish objects Glare and shadows cause eye - strain resulting in more chance of accidents.

Therefore to increase safety , prescribed standard of accidents. Therefore to increase safety,

prescribed standard of illumination is the basic working condition.

Effect of Good Lighting are also direct and manifold, because if affects our sight as well as the

object to be seen. It helps I two ways, by better seeing for work performance and betterenvironment. Better seeing condition causes better discrimination. Concentration, alertness

and less fatigue. Better discrimination causes less spoilage and quick faulty detection.

Sr. No. Area and Work - Room Minimum intensity of illumination in lux

1. Stock -yards, main entrance and exit

roads. cat walks of outdoor plants, coal 20

unloading and storage areas

2. Passage -ways and corridors and stairways,

warehouses, stock-rooms for large and 50

bulky materials, platforms of outdoor plants,

basements

3. Engine and boiler rooms, passengers and

freight elevators, conveyers crating and

boxing departments, store-rooms stock- 100

rooms for medium and fine materials,

lockers rooms , toilet and wash rooms.

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epidermis is involved.

FDBs involve only a redness of the skin, which indicates a mild inflammation.

The Severity is depends on :

Intensity of the radiation.

Absorptivity iof the skin.

Length of exposure.

Secund degree burns

Highly painful and involve deeper portions of the epidermis. Skin is red with a moist surface

and blisters are formed.

Third degree burns

Very severe forms of injury , involving loss of skin and deeper tissue. They are not exceedingly

painful at first because nerve endings are usually impaired or destroyed.

Critical Burns :SDBs exceeding 30% of the body surface.

TDBs exceeding 10% of the body surface.

TDBs involing critical areas.

Moderate Burns:

Superficial SDBs exceeding 15% of the body surface.

Deep SDBs exceeding 15% to 30% of the body surface.

TDBs of < 10% excluding critical areas.

Minor Burns:FDBs

SDBs - < 15% of the body surface.

TDBs - < 2% of the body surface.

LONG TERM EFFECTS (CHRONIC EFFECT ) OF EXPOSURES

System poisoning - (already covered)

Pneumoconiosis - (already covered)

Noise - induced hearing loss

When a person is first exposed to hazardous, the initial change usually observed is a loss of

hearing in the higher frequency range, usually at about 4000Hz. After arrest period away from

the noise, the hearing usually returns to its former level.

Permanent damage from noise is generally classified as noise-induced hearing loss. The long

term cumulative effects of repeated and prolonged hazardous noise exposure result in per-

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Industrial Dermatiti s

The cause of Occupational Dermatitis falls into two major classes - predisposing (indirect)

cause & direct cause.

Indirect Cause

Indirect Cause is generally associated with race, age, sex texture of the skin, perspiration,

season, lack of cleanliness & allergy.

Racial

Complexion, dark skin is not resistant to chemical constituents.

Age

Young workers develop occ. dermatitis easier than older workers

Skin

Dry skin cannot tolerate the action of solvents.

Perspiration

Perspiration may activate the irritation.

Sex

Women are more susceptible

Seasonal

More common in warm weather.

Allergy

Slightest exposure to the allergens can produce reaction symptoms which frequently result in

dermatitis.

Cleanliness

Lack of cleanliness both personal & environment is the cause of occupational dermatitis.

Direct causes

Classified as mechanical, physical, chemical, poison of certain species of plants, biological

Mechanical agents

Injuries caused by mechanical friction that result in abrasion, bruises, wounds.

Physical agents

Such as heat, cold & radiation can cause occupational dermatitis. Dish washer, laundry work-

ers get such dermatitis.

Chemical agents, (organic & inorganic chemicals)

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Biological agents

Bacterial, fungal, parasitic attack the skin & produce systemic disease.

(Animal breaders, agriculture workers, bakers, horticulturist, laboratory technicians)

OCCUPATIONAL CANCER

Occupational cancer is a form of lay toxicity, usually serious in clinical course and outcome,

due to exposure to chemical & physical agents (carcinogens) in the work place. In the workplace the primary route of exposure to a carcinogenic agent is through inhalation, although

injection and skin contact can also be significant.

The two situations which led to the discovery of a carcinogenic risk are an unusual occur-

rence of a rare tumor in a working population or an excess of a common neoplasia in a

specific industrial process.

Causative agents

The number of agents proved to cause cancer in human is still small. Many developed countrie

have classified carcinogenic substances into different groups taking into consideration vari-ous criteria, and prepared national list. In the USA the ACGIH has prepared a list of 12 con-

firmed human carcinogens and 43 suspected human carcinogens.

Confirmed human carcinogens (listed few chemicals only)

- Asbestos

- Chromium compounds

- Vinyl chloride

Suspected human carcinogens

- Benzene

- Carbon tetrachloride- Chloroform

- Formaldehyde

Control of occupational cancer

- Prohibit the presence of carcinogenic substances in industrial precesses

- Processes & transportation in closed system

- Work place monitoring

- PPF

OCCUPATIONAL EYE DISEASES

Hazards to the eye may be in the form of :

- Mechanical agents

- Physical agents

- Chemical agents

- Biological agents

Foreign bodies of various types are very common. But major injuries like lacerations, perfora-

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b) Direct finger pressure into the wound in case of larger bleeding wounds.

c) Tourniquet (seldom needed) use only as a last resort.

2. Avoid touching the wound with hands or unsterile material.

3. Clear the wound with running water and surrounding area with soap or spirit with

clean gauze washing away from the wounds. Apply ready - made adhesive gauze

bandage or sterile gauze and roller bandage as needed.4. Keep the patient quiet, raising the extremity if it is the bleeding part. Give no stimu-

lants.

5. Never apply antiseptic ointment lotion or iodine or germicide to be wound.

Abdominal Wounds :

1. No time must be lost in sending the patient to the hospital.

2. Keep the patient flat.

3. Give nothing by mouth.

4. Maintain warmth.5. If intestines protrude from the wound do not attempt to touch or replace them.

6. Apply sterile dressing and binder as for wounds.

7. Proved careful , immediate transportation to the hospital.

Eye - Wounds :

1. Removal may be attempted if foreign body is not embedded.

2. Do not apply oil or ointment.

3. If there is a foreign body embedded in the eye - ball, send the worker immediately to

the doctor after applying pad and loose bandage.

Chemical Burns of the Eye:

1. Immediate washing of the eye least for fifteen minutes is of great importance.

2. Apply sterile bandage and sent the worker immediately to the doctor.

3. Neutralizing agent or ointment should not be used.

Suffocation :

1. Remove the patient form the source of danger.

2. Make a rapid examination to ensure that the air passages are free, and to clean

them if necessary.

3. Restore natural breathing by artificial reparation, if breathing has ceased.

Insensibility :

1. Send for a doctor. Meanwhile do to the following.

2. Where the patients face is pale, lay him flat and face downwards with his head

turned to one said. If his face is flushed or blue, raise and support the head and

shoulders.

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4. There may be burns either superficial or deep. They depend on the strength of the

electric current causing the injuries.

First Aid : Intelligent and prompt action is required. If the first aider is not cautious, he amy also

receive severe electric shock or even die along with the casualty.

1. If the casualty is still in contact with the conductors, switch off the current. If the

switch is not be found, remove the plug, or cut off the current, by breaking the wire,ensure that you stand on a dry piece of wooden board. Do not use scissors or knife

. When the current is of low voltage the first aider should stand on an insulated

material which is dry. (Insulating materials are rubber soled shoes, wooden planks or

piles of newspaper). Rubber gloves, if available should be won. If not dry coat, cap or

other clothing may be used. Folded newspaper also gives protection. When the

current is of a very high voltage, as in the actual contact with the wire as the current

can pass through the gap (causing an are) the first aider is such circumstances

should keep as far away as possible from the electric wire. The casualty is to be

dragged out by means of a non-conducting material. A walking stick, dry bamboopole wooden plank or a dry rope is to be used..

2. If the casualty is not breathing normally or heart has stopped beating, give artificial

respiration and external cardiac massager for a long time.

3. Treat for shock.

4. Treat for burns if any.

5. Transfer to a hospital or seek the help of a medical practitioner. Who is nearest?

6. Even when the causality has recovered fairly well after first aid is given ; he must be

examined by a medical specialist because electric injuries are liable to relapse.

ARTIFICIAL RESPIRATION

Treatment when not breathing:

1. Loosen all clothings at waist chest and neck.

2. Tilt the head backwards, while supporting the back of neck with your palm. This will

lift the tongue to its normal position. Thus the air passage will be cleared and the

casualty may begin to breathe after a gasp.

3. If breathing does not begin after the above treatment, help movements of chest and

lungs four of five times. This will be usually enough to start breathing. If breathing

does not even now, mouth - to - mouth (to-noise) breathing should be begun.

Mouth - to - Mouth

1. Place the casualty on his back, Hold his head tilted back.

2. Take a deep breath with mouth open widely.

3. Keep nostrils of casualty pinched.

4. Cover the mouth of the casualty with your mouth smugly.

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Poisoning with and Alkalis : If the poisoning was caused by concentrated acids and the

symptoms of esophageal or gastric perforation are absent the stomach should be lavaged

through a thick stomach tube using for it 6-10 liters of warm water mixed with magnesium

oxide (20 g per litre of liquid), or lime water. Sodium carbonate is contraindicated for gestic

lavage. Minnor lavage. i.e. drinking 4-5 glasses of water and then inducing vomiting will not

alleviate the patient condition and sometimes may even promote absorption of the Poisson.

When the poisoning is due to concentrated alkalis. The stomach should be immediately leavedwith 6-10 litres of tepid water or a 1 per cent citric or acetic acid solution within four hours of

the poisoning. When a stomach tube is unavailable and the patient grave condition (swelling

of the larynx) prevents a stomach lavage, mucilaginous solutions are given. 2-3 percent citric

or acetic acid solution (1 tablespoonful every 5 minutes) or lemon juice. Rising of the mouth or

administration of sodium hydrochloride solution is contraindicated. The patient should be im-

mediately admitted to a medical institution where he will be given the necessary urgent medi-

cal help.

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effect of fatigue. The factors that produce fatigue are;

> Monotony work.

> Environmental factors such as poor illumination, bad climate, noise etc.

> Manual or mental work intensity.

> Psychological factors such as responsibility, worry, conflict etc.

> Illness, pain.

> Eating habits.

If a person exposed to continuous daily fatigue gets clinical fatigue or chronic fatigue.

Chronic Fatigue Clinical fatigue

Increased imitability Headache

Intolerance Giddiness

Anti-social behaviour Rapid breathing

Tendency to depression Loss of appetite

General weakness Indigestion

Dislike to work Insomnia

Sensation of fatigue is painful when rest is not permitted. For heavy work there is a formula to

estimate the percent time which should be allotted to rest.

Mmax - m

Trest (%) = ...................... x 100

Mmax - m

Where Trest % rest time

M max upper limit of metabolic cost for sustain workM metabolic cost of the task

Mrest resting metabolism

Biomechanics

It is a study of the structure & function of the body in relation to man - machine system.

Equipment & work place are so designed that there should be space for movement, proper

approach and should have means of access. The body dimensions and static dimensions of

machines / equipment should be property matched.

The most parts which are most suspects able to be affected due to non or poor consideration

of human factors in workplace are :

> Upper extremity (shoulder, elbow, wrist, hand and fingers)

> Lower extremity (knee, ankle, and foot)

> Back - (spine, and the muscles surrounding them)

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tortured they result in disorders, like foot strain, osteoarthritis hallelus, valgus, metatarsalgia,

kohlers disease, chronic bursitis, etc. Due to the pain and difficulty in negotiating the func-

tions of the foot the efficiency of the workers reduces beside his physical problems.

Low Back Pain : Postural error, assumed in the course of some occupation leads to low back

pain. These pains are because of the interference with the functions of normal muscles. When

muscles go under postural stain, leading to spasm usually in the lumbo-sacral region or onthe sacroiliac region joint disorders of the part results. Any occupational requiring long work

hours with improper posture should be avoided.

Control Through Human Factors Engineering : To prevent those disorders human factors

engineering has to play a great role. The discipline which comes to play their role in preven-

tion of them is the biomechanics. Its principles in view of the applicability must be used while

designing machine, work places and methods to be used by the employee to perform their

task. The main biomechanics problems which can help in prevention of occupational health

disorders are.Straight back rule

Belly button rule

Swinging arm rule

Straight arm rule

Straight wrist rule

Eye rule

Skin rule

Think first rule

No brain machine rule

Straight Back Rule : All the forces which come down the spine compresses the inter-vertebraldiscs and as a result of continuous and repetitive squeezing they can rupture and bulge out

producing severe pain. Most back injures are build over a long period of time by repetitive

pounding of the discs, caused by improper methods. After sometime some minor lift can

produce such rupture even lifting a small pin. Straight back rule helps to design methods to

minimize the forces on these discs. To avoid such forces, one should use Pelvic tilt by pulling

the stomach muscles. The pelvic tilt can also be achieved by placing support under one leg.

When bending cannot be eliminated through work place or methods designed , it could be

done with keeping cannot be eliminated through work place or methods designed, it could be

done with keeping the back straight and bending the legs. Any bending without lifting, twist-

ing, impacts and frequent change of position should be avoided by proper designing of the

workplace and work methods. When seated a support for the back to keep the muscles away

from getting fatigued should be used.

Belly Button Rule : Loads that are held, lifted or carried should be kept near the belly button.

The weight of 30 pound load next to the belly button (about 8 away from spine) exert 24/

pounds where as when weight is moved out 12 from the belly button, it would be 20 from the

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2. Are all movements, holds and delays necessary?

3. Is the back straight?

4. Is the back free from twisting?

5. Are elbows by the side of the arms?

6. Are movements natural and ballistic?

7. Are wrists straight?

8. Is wok area free of obstructions?9. Are stop switches, controls, lock outs, and guards convenient and adequate?

10. Is the weight lifted less than 32.2 - 1.2 x the number lifts per minutes and is the

weight carried less than 32 lbs?

MACHINE DESIGN CHECKLIST

1. Is equipment operated with back erect, no twisting, supported if seated, foot rest if

standing?

2. Are control and materials near stomach and if sequence of use?

3. Can operators movements be ballistic?4. Can equipment be operated with straights wrists?

5. Are readouts and gags simple, in sequence, and do not require head movements?

6. Are handles and surfaces nor applying pressure on small skin areas?

7. Are stop and off switches where operator will be?

8. Are guards easy to remove and replace without tools?

9. Does equipment require minimum tools which are displayed in order to use?

10. Is there accumulation of material before, and after machine operation?

Anthropometry

Literally meaning the measure of man, anthropometry is concerned with measurement ofthe human body. Included in these measurements are body dimensions, range of motion of

body members, and muscles strength.

For application to workspace and equipment design, static dimensions are grouped in three

basic categories : minimum, maximum and adjustable dimensions. Dynamic dimensions, on

the other hand, usually refer to reach capabilities of the arms legs.

Minimum dimensions provided clearance for the operators in the working space, or for in-

gress and egress.

In setting minimum dimensions the designer needs to consider first the percentage of work-

ers who will be accommodated. Obviously , people vary widely in such static dimensions as

height, weight sitting - height, breadth at shoulders, at elbows at buttocks, and thigh clear-

ances to name a few of the most important dimensions.

Maximum dimensions assure that the smaller members of the population will in fact be able to

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3. Plan the process & equipment around the system requirements.

4. Plan the layout around the process & layout.

5. Plan the final enclosure around the layout

6. Use mockups to evaluate alternative layouts and to check the final layout

Sitting

Proper design of the chair is essential to provide the kind of support required for the specifictask assigned to the operator. The seated person must be able to choose and change his

body posture when prolonged sitting is required. Changing adjustment of the driver seat or of

the steering wheel if it tilts, provide a new posture that should reduce the fatigue of the opera-

tor.

Displays

Proper selection, design , and layout of displays (displays may be visual, auditory) are impor-

tant to provide the necessary input to the operator.

Controls

The selection, design and location of controls require the same care as is applied to displays.

- Choose the type control-lever, knobs, swithces, hand wheels appropriate to the re

quirements of the task.

- Use hand controls for work to be performed quickly and accurately and foot controls

for work that necessitates considerable force.

- Control levers should move in the direction which corresponds to the movement of

the object controlled.

ROLE OF NUTRITION IN OCCUPATIONAL PRACTICEThe ultimate aim of occupational health practice is to ensure that the man on the shop floor is

not subjected to undue stresses is not exposed to situations which will lead to occupational

ailments and diseases, and is able to undertake strenuous physical tasks without being

easily fatiqued. The nutrients in the diet, play an important role in achieving the above objec-

tive. The various nutrients of relevance are the dietary calories, protein vitamins and minerals

, water and common salt.

Vitamins : Whenever any additional work is done, additional energy supply is needed. The

source for such energy release is the carbohydrate and fat contents of the food being con-

sumed and digested. In the metabolism of the digested food making use of oxygen as fuel,

many enzyme systems are involved, which have as constituents, vitamens such as B1 (Thia-

mine) and B2 (Riboflavin). Besdies, many other vitamins and trace elements have vital roles

to play (Table - 1).

Nutrient Requirement for Maintaining Industr ial work output :

1. The calorie content of food should be adequate to meet.

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industrial hygiene part2 paper v

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