industrial hygiene part1 paper v

7/27/2019 Industrial Hygiene Part1 Paper V

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INDUSTRIAL HEALTH PROGRAMME

OBJECTIVES

TO PROTECT EMPLOYEES AGAINST HEALTH HAZARD IN THEIR WORK

ENVIRONMENT

TO FACILITATE PLACEMENT & ENSURE THE SUITABILITY OF INDIVIDUAL

ACCORDING TO THEIR PHYSICAL CAPACITIES, MENTAL ABILITIES IN

WORK THAT THEY CABN PERFORM

TO ASSURE ADEQUATE MEDICAL CARE & REHABILIATION OF THE OCCU

PATIONALLY INJURED

BENEFITS

GOOD EMPLOYEES HEALTH GAINED BY CONTROLLING HAZARDS IN

THE WORK ENVIRONMENT

REDUCTION IN DISCOMFORT & DISABILITIES MAKES INCREASED

PRODUCTION.

PRODUCT & EQUIPMENT WITH BUILT IN PROTECTION AGAINST HEALTH

PROBLEMS.

TOXICITY DATA

INDUSTRIAL HEALTH PROGRAMME

COMPONENTS

OCCUPATIONAL HEALTH INDUSTRIAL HYGIENE

The employees who are required to work in industries are to be protected & kept in a healthystate, because the state of health of the worker can influence his ability to work safely and

efficiently.

Has been defined as that science and art devoted to the recognition, evaluation and control

of the those environmental factors or stresses, arising in or from the work place, which may

cause sickness, impaired health or significant discormfort and if efficiency among workers or

among the citizens of the community


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Solid Operation Pouring Dusts Cement, Quartz, Local exhaustMixing fibrous glass Ventilation, PPESeparation Wet methodsExtractionCrushingLoadingBagging

GENERAL CONTROL METHODS

General methods for Controlling environmental factors or stress include the following:

1. Substitution of a less hazardous material for one which is harmful to health-

< Replacement of white lead in paint pigments by zinc, barium.

< Use of phosphorus sequsesulfide instead of white phosphorus in match- making.< Shot blasting instead of sand blasting.

2. Change or alteration of a process to minimise worker exposure-

< Brush painting or dipping instead of spray painting.

< Arc welding to replace riveting.

< Automatic elecrostatic paint spraying instead of manual compressed air paint spraying.

3. Isolation or enclosure of a process or work operation to reduce the number of employees

exposed-

< Physical barrier - acoustic panels, to minmize nosie transmission.< The hazardous job can be isolated from the rest of work operations and thus eliminate

exposure.

4. Wet methods to reduce generating of dust-

< Wetting of the floor before sweeping

< Wetting of dusts.

< Water under high pressure for cleaning castings in place of sand blasting.


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4. Gas furnace or oven heating Vapours, heat, nosie Local exhaust ventilationHood with bolwer toexhaust vapours. PPE.

5 Crushing & grinding Air borne dust, nosie, Local exhaust ventilation.Eronomic hazards. PPE, Correct posture.

6 Metalizing Dust, fumes of metals and Local exhaust ventilationfluxes, heat & non-ionizing PPE.

7 Microwave and radio frequency Heat & non-ionizing Enclosure, Local exhaustheating radiation, noise. Ventilation.

PPE.8 Molten metals Toxic gas, metal fume, dust Enclosure, Local exhaust

ventilation.9 Paint spraying Toxic & irritating solvents, Ventilation for the paint

toxic pigments. Booth.PPE

10 Punch press, drawing Contact with lubricant PPEoperations inhalation of lubricant mist,

nosie.11 Welding Toxic gases or fumes, PPE

radiation Local exhaust ventilation

TOXIC CHEMICALS - HEALTH HAZARDS & CONTROL MEASURES

Chemical TLV Hazard Control measure

1 Acetaldehyde 100ppm Irritation to skin & URT. Process should be wellInfirmation of the nose, enclosed and isolated.

Throat eye Adequate ventilation . Useof Suitable personalprotective equipment

2 Ammonia 25ppm Strong irritant and can Process should be wellproduce sudden death enclosed and isolated.from bronchial. Adequate ventilation . Use

of Suitable personalprotective equipment

3 Arsenic 0.2mg/m3 Cough ulceration of the Adequate ventilationcumulative poison. Hygienic condition to be

maintained . Use of suitable personal protectiveequipment.

4 Asbestos 5 fibers/cc. Fibres/cc in the lungs Local exhaust exhaust>5micrometer (asbestosis) ventilation.Use of suitablelength. Personal protective

equipment.

5 Benzene 0.5ppm Affects central nervous Process should be wellsystem, skin contact enclosed and isolated.Produces dryness & Local exhaust ventilation.Cracking of the skin. Use of suitable PPEHuman carcinogenic.


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Chemical TLV Hazard Control mesaureToxic symptoms-pain inabdomen, constipation, loss ofappetite, and general emaciationfollowing by nervous prostrationknown as lead-palsy slowed by

paralysis. Sometimes a blue linemay be observed in the gumsmargins.

17 Mercury 0.05mg/m3 Metallic Mercury (inorganic): Same as abovefor inorganic Cumulative poison, affects brain& non-alkyl cells kidney cells. Tremors in hand,organic loosing teeth.compounds.

0.01mg/m3 Organic Mercury:alkyl Deformation in hand, notcompounds. walk properly.

Exposure to mercury vapourhas also been observed tocause a browndiscoluration in the lens ofthe eyes, a condition knownas Mercurillentis.

18 Phosphorus 0.1 mg/m3 Elemetal phosphorus Same as abovecauses chronininflammation of the lower

jaw, a particularlyunpeasant condition known

as Phossy-jaw.Affects nervous system,bone.

19 Beryllium 0.002 mg/m3 Affect skin, causing Same as abovedermatitis. Pneumoconiosisand can affect kidney &liver.

20 Manganese 1 mg/m3 Highly irritant to lungs, Same as aboveaffects central nervoussystem.

The resultant effectresembles Parkinsons

disease.


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firstly to supply sufficient quantity of fresh air, secondly to distribute the air satisfactorily

throughtout the workroom and thirdly, to maintain reasonable conditions of comfort the opera-

tors. These functions are interrelated and are to considered in the design of factory buildings

the point of view of ventilation.

The amount of ventilation required is often governed chiefly by physical consideration for

controlling air temperature air distribution and air velocity and depend generally on the follow-ing

factors.

> Size (including height) and type of room or building and its usage.

> Duration and type of occuptants and their activities.

> Heat gain from sun, hot manufacturing process. Machinery and occupants.

> Temperature conditions desired inside the building in reaction to outside conditions pre

veiling and

> The operation of the ventilation system.

Ventilation systems are divisible into two main group (i) natural ventilation and (ii) mechanical

ventilation. Many times mechanical vitiation is employed to augment the vetilation obtained by

natural means.

NATURAL VENTILATION

Principle: Forces Which operate to induce natural ventilation in buildings are due to (I) pres-

sure exerted by the outside wind, i.e. wind action and (ii) the temperature difference of the airwithin and without building i.e. the thermal need causing chimney effect. The force exerted by

wind strikes a building; positive pressure is created on the leeward side, i.e. at the lee of the

building at the sides and over the roof immediately behind the windward wall, If adequate

openings, suitable placed in reation to these pressure areas, are available, it should be pos-

sible to combine the effects of the varying wind pressures and move air rapidly through and

within the building. At or near the windows, rate of air movements induced owing to the pres-

sure difference will be high, but at the centre the air movement should be eliminated by

increasing the preparation of effective ventilation openings in the wall and roof and by suitable

orinentaion of the building in relation to the prevailing winds.

Thermal head sets up the usual convection currents with the movement of warm air upwards

to leave opening in or near the roof , and be replaced to cool air entering at a lower level.


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upward flow of air. Wind action in any directions does not clause interference with chimeney

effect but supplements ventilation by creating suction through wind jump.

Cowl type roof vetilators: Natural extraction of air form buildings can be obtained by the

provisions of cowl type roof ventilators also. The performance of the roofs cowls depends on

the differenence between the temperature of the external and internal air, on the height of

these ventilation above air intake, on the velocity of the external wing and on the cross -

sectional area of the ventilators., An example of modern roof cowl is the Robertson Ventila-

tors shown in figure given in the next page. As will be noted type circular wind band around

the ventilator causes a wing jump resulting in an upward deraught of air from inside the

building which supplements the ventilation due to chimney effect depending on the height of

the ventilator above the intake openings in the side walls. Capacity of this ventilator for a 60cm

(24 in.) Diameter cowl in relation to temperature difference, height of ventilator above intake

and wind velocity is given by the equation:-

Q = A(3.3 5.9H (t1 - to) + 0.0035V)

Where Q is expressed in cu. Meters /min. A is the cross - sectional area of the ventilator is sq.

Meters, He is the height of the ventilator above the inlets in meters, t1 and to are the internal

and outside temperatures in OC and v is the wind velocity in kilometers /hour. Another type of

cowl ventilator is the rotating cowl ventilator shown in figure below which is intented to pro-

duce the same effect. The type illustrates is carefully balanced and provide with a large reser-

voir for lubricant so that it does not gent jammed or seized and needs attention only at long

intervals.

Mechanical ventilation: Ventilation by natural means is not always practicable in which case

ventilatin by mechanical means is resorted to workrooms or work places where ventilatin

openings cannot be provided due to their situation with respect to surrounding buidings or

due to the process carried on in them and large buildings where natural menas fails to provide

the necessary ventilation, are examples where mechanical ventilatin would be necessary.

Mechanical ventilation is brought about by either one or both of the following two methods:


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The velocities depend upon the nature of the installation and the extent of quietness required.

The air inlets should be designed and the discharge velocity should be such as to cause deep

currents and to remove dead spaces. The air velocities should not be excessive to the extent

of interfering with the manufacturing process or of causing unpleasantness but there should

be currents of sufficient strength and variability so as to provide a pleasant environment.

Combined plenum and extraction system: Better control of ventilation is obtained by this

system of ventilation, in wider buildings, by supplying appropriate quantities of air and at

suitable velocities at the required areas by plenum ducts and extraction the air into return

ducts and sometimes rusticating this air after properly mixing it with cooled fresh air, com-

pletely satisfactory ventilation can be obtained. In a confined supply and exhaust system it is

preferable to provide slightly excess of exhaust, if there are adjoining occupied spaces and

slight excess of supply, if there are no such spaces.

Mechanical roof ventilation: Powerful mechanical roof ventilators of unit type are increas-

ingly being used for augmeting natural ventilation in building with large widths or where theheat load is very heavy. When these are provided, it is important that the openings within their

area of influence should be closed to avoid short circulation exhaust fans exercise very little

influence beyond a velocity control of about 15m/min. (50ft./On) which is just a short instance

form the fan.

The amount of air required:

a) Based on Heat Air Gain: The amount of ventilation required can be calculated on the

basis of total heat gains from sun, not manufacturing processes, machinery and occupantswithin the buildings, determining in advance the temperature rise which would be acceptable.

The volume of air required in removal of sensible heat gain (in kcl. per hour) can be calculated

from the formula

kcal/hr. x 0577

Q = ----------------------------------------------

Temperature rise in

Where Q is the volume of air in cubic meters/ min. (or where Q is the volume of air in cu. ft./

min.)


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The protective clothing is generally made of aluminized asbestos cloth usually backed up with

felt or other insulation material. Aluminized fiber glass is also effective. The operator may be

equipped with matt, leggings, aprons, jackets, helmets and special arm sleeves according to

specific operations. The protective clothing those parts of the body which are facing the hot

objects need be covered. Protective shield faced with aluminum when interposed between

areas of high radiant heat exposure and workers have also proved successful in many cases,.

These shields which may be portable or semi- portable according to the work situation, have

sometimes been preferred to use of blowers or fans and personal clothing.

Local exhaust ventilation:- Local exhaust ventilation is one of the most important methods

of control of atmosphere contaminants. The principle is to crate a sufficient movement of air to

withdraw contaminants at point of origin and convey them to a safe point for disposal. An

exhaust Consists of four major parts:

> Hoods or enclosures near source of contaminant.

> Ducting to connect hoods into system.

> Collection equipment.

> Fan.

Dusts is usually more difficult to control these gases, vapoures, mists, and fumes. Dusty

operations tend to project particles so that the hood must provide velocities sufficient to draw

them into the exhaust system. Exhaust hoods should enclose the processes completely as

possible or the hood should be located to take advantage of the directional effects of the dustflow. Dust removal system generally requires higher air velocities and dust of heavier gauge

metal then those designed for gases. Hoods or enclosures may be in the form of booths, cane

piece, lateral hoods, down draft through grill openings below the process or elect type hoods.

The object is to remove the interference without drawing it through the breathing zone of the

operators and with minimum interference with processing. Dust connect the hoods to the

central fan, distribute the air flow in the contaminate to the requirements of each inlet, and

maintain adequate pipe velocity to convey the contaminant to the point of discharge. The

system should be balanced so that each hood draws the proper amount of air:


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It has a wider meaning including up keeping of all industrial activities in orderly manner to

minimize the accidents due to improper planning, placement, arrangement, handling etc. ev-

erything in its proper place, it pays attention on removing all unsafe conditions in the plant and

thereby increasing safety and productivity.

Results of Good housekeeping

1. It is essential routine support of industrial safety and health.

2. A large number and wide range of accidents owing to bad housekeeping can be

eliminated by good housekeeping.

3. It aids to good maintenance and working as complementary to it, both, increase over

all safety and productivity

4. Machines , tools and equipments work better in clean condition and boost up the work

manship.

5. Clean and well maintained floor, stairs, walkways, cat ways, doors, window, lifts,

latrines, urinals, washing facilities, furniture, record, dress, first - aid and protective

equipments and proper layout of materials, tools and process flow certainly avoid

many accidents.

6. Accidents due to stepping on or striking against objects or fall of persons and objects

would be controlled.

7. Overall life and utility of plant, building and equipment are increased due to good house

keeping

The Causes of poor Housekeeping: These are well evident from above tables. The causes

contributing the maximum accidents are

1. Stepping on or striking against objects

2. Handling goods or articles

3. Struck by falling bodies

4. Persons falling

5. Use of hand tools and

6. Other or miscellaneous.


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ACTION OF TOXIC CHEMICALS

Acute effect (short term)

Immediate results of some kind resulting in illness , irritation, or death. Acute poisoning caused

due to sudden exposure to high concentration of toxic chemicals. Irritation, asphyxiation,

cyanosis, and burn injuries are acute effect of toxic substances.

Chronic effect (long term)

Continued exposure to hazardous substances during working lifetime may cause chronic

effect. Chronic illness is characterized by symptoms or disease of ling duration. Continuous or

repeated exposure to toxic substance throughout a working lifetime may cause systemic poi-

soning or damages organ/tissues and exposed person may get occupation disease - irrevers-

ible damage.

When hazardous chemicals (particulate matter, liquid etc) enter into human system by inha-

lation, ingestion or skin absorption and if it goes into blood stream then systemic distribution

takes place and it gets deposited in any one of the organs. The organ if suffers most severe

damage then the effect is considered as chronic effect and the injured person may have

occupational disease.

Many harmful substances can be stored (deposited) for long periods of time in various parts(organs) of the body. In toxicity studies the organ that suffers the most severe damage ap-

pears

to store most of the toxic material is called the target or critical organ.

Many materials including organic compounds undergo detoxification in the body. The body

converts it to something else that usually reduces its ability to cause injury. Occasionally, the

conversion enhances the toxicity. The conversion products may appear in the urine or blood

as metabolites. The level of metabolites of toxic agents in the urine indicates that exposure

has occurred.


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TOXIC EFFECTS OF EXPOSURE

Irritants

Irritation means some sort of aggravation of whatever tissue the material comes in contact

with. Many irritants are liquid. Ammonia which is very soluble in water irritates the nose and

throat because the moisture on the surface absorbs the ammonia. Nitrogen dioxide, being

much less soluble, acts mainly on the tissues in the lungs. Some chemicals produce acute

pulmonary edema (fluid in lungs), which begins as an intense irritating that is later manifested

by coughing, cyanosis. Respiratory irritants may be inhaled in gaseous form, as mist of as

particles.

Irritants can be subdivided into primary and secondary irritants. A primary irritant is a material

that exerts little systemic toxic actin because the products formed on the tissues of the respi-

ratory tract are nontoxic.

A secondary irritant produces irritant action on mucous membranes. The direct contact of

liquid

hydrocarbons with the lung can cause pneumonitis.

Irritants injure the body by inflaming the tissues. Capillaries dilate & fill with blood causing

redness & increases heat. Fluid passes from the blood into the spaces between the tissues

causing pulmonary edema.

Strong irritants can produce blisters.

Ammonia can injury to upper respiratory tract.

Chlorine damages entire tract.

Acids irritates lower portion of the tract.

Zinc, nitrates, acid, alkalies damage the skin.

Irritation phenomena are reversible after short term exposure. If exposed person taken out of

the exposure, the irritation, may quickly disappear.

> Irritant affecting upper respiratory tract Formaldehyde, Ammonia, Sulfer-oxide

> Irritant affecting upper respiratory tract &lung tissues Chlorine

> Irritant affecting air sacs Nitrogen dioxide, Phosgene,

Carbon monoxide


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Mutagenesis - A mutagen is something that affects the genetic system of the exposed people

in such a way that it may cause cancer of undesirable mutation to occur in some letter genera-

tion.

Teratogenesis - refers to the production of abnormal offspring. It produces malformations of

the fetus without inducing damage to the mother or killing the fetus.Thalidomide, steroids and ionizing radiation can produce teratogenic effect.

PNEUMOCONIOSIS (occupational lung diseases)

When particulate (dust) in air is inhaled, it goes to deep portion of lung (if not retained in

airways or expelled through cough.) The particulate if not soluble in body fluid, retains in lung

and proliferation starts and this deposition (inert benign growth) damages lung tissues and

leads to an occupational disease- Pneumoconiosis.

Acute reactions to inhaled dust can be described as irritant, toxic, or allergenic. Chronic expo-

sure to dust is associated with various types of pneumoconiosis.

Type of Pneumoconiosis

Silicosis - Free silica (crystalline material) is able to cause silicosis. Silica dust moves out of

air spaces into other portion of lung. In the lung where silica dust is deposited & accumulated,

a fibrous tissue develops & grows around the particle that does not permit the ready passage

of oxygen & carbon dioxide and it proliferates. Fibrous tissue cut down the amount of normal

lung tissue as a result; functional volume of the lung is reduced. Fibrous tissue slow down orvent prevent the diffusion of oxygen from lung to blood.

Prevent the diffusion of oxygen from lung to blood.

Permissible exposure limit;

Crystalline dust - 1.3 mg/m3

Portland cement -10 mg/m3 total dust containing < 1% quartz.

Coal dust-2mg/m3, respirable dust containing < 5% quartz.

Asbestosis - Another kind of pneumocentesis, involving specific lung changes is called

asbestosis. It is caused by inhalation of asbestos dust. Certain grades of asbestos can be

carded, spun & woven, others can be laid & pressed to form paper.


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Cn is the conc. of contaminant in period n.

Tn is nth or final time period during the shift.

TLV of mix ture of sub substances.

C1 C2 C3

------------------- + ------------ + -------------

T1 T2 T3

(TLV of mixture if it is less than 1 -Safe, if more than 1- not safe)

C1 - concentration of x chemical

T1 - TLV of x chemical

C2 - concentration of y chemical

T2 - TLV OF y chemical

C3 - concentration of z chemical

T3 - TLV OF z chemical

Short Term Exposure Limit (TLV-STEL)

STEL is the maximal conc. to which workers can be exposed for a period of upto 15 min-

utes continuously without suffering form any one of the following :

Irritation

Chronic or irreversible tissue change

Narcosis, impair self-rescue, or materially reduce work efficiency.

The STEL is not be exceeded at any time during the 15-minute excursion period. No more

than four 15-minute exposure periods per day are permitted with at least 60 minutes be-

tween those exposures periods.

Ceiling (TLV-C) is the concentration that should not be exceeded even instantaneously.


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Some time sampler is filled with the help of nipple device and sample is

directly introduced into the analytical instrument for analysis.

2. Sampling by So lvent Scrubbing.

Absorption of toxic contaminants by solvent is often used n air sampling. The advantage of

the method lies in the possibility of simultaneous concentration of wide range of substanceswith high selectivity of the determination. In this method sample is collected by passing the

polluted air through a glass vessel filled with suitable organic or inorganic solvent depending

upon the sample composition. The most effective method of scrubbing the contaminants

from air is by the use of an absorber with a porous plate, which enhances the absorption of

contaminants owing to the large surface area available. While selecting the solvent

and a flow rate, one should remember that the use of volatile organic solvent , a flow rate

above 11/min. leads to considerable loss of solvent and simple due to evaporation. Due to

which error the extent of 50% or more might observed in the quantitative determination of

pollutants. The extent of absorptions depends upon the nature and concentration of contami-nants, flow rate, ambient temperature and the property of absorbent.

3. Sampling by Derivat izat ion

Derivatization of a sample is to covert the pollutants of interest into a form convenient for a

chromatographic analysis.

4. Headspace Monitoring

In this method, several liters of air is passed through the absorber containing a suitablesolvent till the saturation occurs and the gas phase above the absorbent is sampled and

analyzed usually by using GC technique.

5. Sampl ing by Cryogenic Concentrat ion

The method of cryogenic concentration involves freezing of the toxic species from the

polluted air at a temperature significantly lower than the boiling point of the sample. This is

carried out by pumping the polluted air through a cooled trap or condenser with a large

surface area. Metal capillaries or steel / glass tubes packed with a inert material such as glass

wool, Copper shot glass beads etc. are used to increase the cooling surface area.


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Sampling Procedure for Industrial Hygiene Surveys

Chemical Hazards

Gases & Vapours Field Indicator Tubes yielding direct readings.

Collected in containers or absorbed on charcoal for laboratory

evaluation.

Fumes & Mists Absorbed & measured in the field.

Absorbed & evaluated in the laboratory.

Collected on filter media & analyzed in the laboratory.

Dusts Collected by a personal air sampler, fractionated into respirable

size by a cyclone separator and the fractions weighed to deter

mine the concentration.

Collected on an open-faced filter & weighted.

Collected in an appropriate manner & counted.

Physical hazards

> Pressure may be measured barometrically.

> Temperature may be measured by thermometer, thermocouple, or radiometer.

Determination.

> lionizing radiation may be measured by survey meter, personal dosimeter, or film badge

techniques.

> A number of direct reading meters are available for non-ionising radiation.

> Noise level measured with sound level meter or octave band analyzers.

> Vibration may be determined with additional sound level equipment.

Air Sampl ing Equipment

> Evacuated Container (250-1000 ml capacity): Heavy wall glass container (air is evacu

ated & sealed).

> Displacement (gas or liquid ) Collector: 250 t-300 ml glass tubes.

> Flexible plastic bages: Air is filled by suction pump or a hand pump.

> Dragger Tubes : Colour changed is compare with standard colour stains.

> Continues Air Sampling Equipments: Battery operated pump, Rota meter, filter holder

trapping media.

> Suction Device Pump:

Manually operated piston pump

Aspirator bottles

Personal sampling pumps

High volume air sampling pump.


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2. The factors which determine the duration of sampling or the volume of the air to be sampled

are as follows

a) Sensitively of the analytical procedure

b) The threshold limit value (TLV) of the particular contaminant

c) The expected air concentration

Another considerable necessity in determining the duration of the sampling is that it should

usually represent a complete cycle of operations. This is useful in determining the operators

weighted exposure. Another technique is to sample on a regular schedule e.g. so many min-

utes every hour. This procedure usually requires collection of more number of samples the

cyclic sampling procedure and is more or less subtituting statistical approach for observation.

3. The number of samples to be collected depends on the purpose of sampling. The effi-

ciency of the control measures method is in operation and the other while it is switched off. On

the other hand large number of samples amy be necessary to accfurately define average

daily exposure for a worker engaged in the particular operation. The concentration of the air-

borne contaminant is also a factor to determine the number of samples needed. A Few samples

may be sufficient of the concentration if definitely high but if it is near TLV, A minimum of 3 to

5 samples may be necessary to indicate exposure for a certain task of cycle of operation.

Sampling instruments: The basic requirements of any air sampling instruments are:

a) Source of suction, which may be an electrically or hand operated pump, an aspirator

or squeeze bulb

b) Collecting medium - it should be able to efficientlyretainn the contaminants to be

sampled by absorption, an aspirator mechanical retention and control.

c) Flow meter to indicate and control the rate of suction of air to calculate the amount of

air sampled. The flow meter attached to instrument must be calibrated with wet or

dry gas meter.


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Volumetric Method: By the use of standard solution for titration. Examples are acid gases

which are titrated with a basic reagent.

Physical Methods: The physical methods widely used for the determination of the various

contaminants are emission spectroscopy, infrared and ultra - viol4et spectroscopy, infrared

and ultra - violet spectroscopy, mass spectruscopy, paleography, x-ray diffraction, gas, chro-

matograph and atomic absorption spectrophotometry.

Direct reading instruments for determining concentration of airborne contaminants:

Colorimetric Indicators: The principle of these indicators has been described earlier under

colorimetric method. The three types of colorimetric indicators are being used:

1. Glass indicator tubes containing solid chemicals

2. Chemically treated filter paper

3 Liquid regent.

Direct physical method for analysis : Number of direct reading instruments have been

developed by various manufacturing based on the physical method for analysis. The various

physical method applied have already been briefed earlier.

The factors taken into consideration for selection particular instruments are simplicity, speci-

ficity, stability and accuracy.

BIOLOGICAL MONITORING

One of the most useful means of assessing occupational exposure to a harmful material is

the analysis of biological samples obtained from the exposed workers. This analysis may

provide an indication of the body burden of the substance (deposition of harmful material in

any one of the organs), the amount circulation in blood, or the amount being execrated.

In many cases, biologic monitoring has great advantages over air sampling; substances be-

ing absorbed through the skin and gastrointestinal tract are accounted for.

Examples of analyses which can be performed on biaoloigcal samples:

1. Analysis for the unchanged substance (e.g. lead, arsenic, mercury) in body fluid &

tissue (Blood examination).


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PERSONAL PROTECTIVE EQUIPMENT (PPE)

RESPIRATORY PROTECTIVE DEVICES

Air purifying divices Air supplied devices Self-contained

breathing apparatus

Air line respirator

Mechanical oxygen cylinder

filter respirator

Constant flow pressure - demand

Flow

Chemical cartridge demand flow

Respirator self-generating

Type

Mechanical / chemical demand typeFilter respiratior

Pressure

Demand

Type


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> Gauntlets - Gloves for hot and sharp metals - High tensile strength thermal

conductivity flame retardate

Cotton or leather gloves friction and dusts

synthetic rubber gloves acid, alkali

Neoprene - dipped cotton liquid irritants

Reflective aluminized clothing radiant heat

Air - cooled jackets/suits. high temp

Lead - bearing material ionizing radiation

5. legs:

> Safety shoes - leather, Rubber, asbestos 9Hoc special) IS - 11226- 1985 leather

(molded) Nitrite rubber sole. steel to (or reinforec plastics, hard rubber)

> Specification - light weight, artistic directly injection molded PVC sole vaccines nitriterubber sole.

> Legging-

6. Body:

> Overalls - PVC, Asbestos (As supplied hood), Aluminized (1090O C). leather (for heat,

uv, IR rays , hot metals)

7. Fall protection:

> Safety bell with full supported body harness,

> Crawling boards.

> Flame retardant IS -11871

In place of asbestos fabric, available in Denim/Drill/Canvas fabrics is used and also Fire -

tarde welding blankets is the alternative for asbestos.

> Protective Creams And Lotions ................... help minimize skin contact with irritant

chemicals harmful agents.

> Fall protection..................Safety belts, life lines, crawling board


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Selection of the proper type of respirator is based on;

a) Nature of hazardous operation (Nitration, sand blasting, furance)

b) Type of respiratory hazard (as above)

c) Location of the hazardous area (open space, confined space)

d) Period of time for which respiratory protection must be provided (for escape for attend-

ing leakage, for working in that environment)

Classes of Respiratory Protective Devices

Air purifying devices

The air purifying device cleanses the contaminated atm.

Chemicals can be used to remove specific gases and vapours and mechanical filters can

remove particulate matter.

Limited in its use to those environments where there is sufficient oxygen to sustain life.

Mechanical filter respirators:

Respiratory protection against airborne particulate matter. But they do not provide protection

against gases, vapours of oxygen deficiency.

They consist of a face piece, quarter mask, half mask or full face design.

Filters made up of a fibrous material that removes the harmful particles by trapping them as

air is inhaled.

Chemical cartridge respirators:

Protection against concentration-10 ppm to 1000 ppm.

Chemical filter containing chemicals purify the inhaled air. May be used for self- rescue in

times of emergency.

Should not be used for : material extremely toxic in very small conc. Harmful gaseous matter

which cannot be detected by odor. (Methyl chloride, hydrogen sulfide ), chemicals highly

irritating to eyes.

Mech./ Chem. Filter respirators:

For spray painting and welding operations


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43

> The max. hose length is 300 feet (91.5m)

> The max. permissible inlet pressure is 125 psig.

> Constant - flow units must deliver at least 4 cfm (115 lits/min) measured at face piece.

> When helmets or hoods are used , the flow rate must be at least 6cfm (170lits/min).

Demand flow> Deliver air flow only during inhalation, (for high pressure comp. air cylinders.)

> Suitable pressure regulator is req.

Pressure Demand Flow

> For those conditions where the possible inward leakage is unacceptable.

> It provides a positive pressure during both inhalation and exhalation and must be de-

liver a flow of at least 4 cfm (115 lits/min) (with internally lubricated piston-

type compressors, overheating may produce CO. therefore either a constant

- monitoring analyzer or a heat rise alarm should be in-

stalled).

2. Self contained breathing apparatus:

> Provides complete respiratory protection against toxic gases and an oxygen deficiency.

> The wearer is breathing with a system that admits outside air.

> The oxygen or air supply of the apparatus itself takes care of respiratory requirements.

Oxygen cylinder rebreathing type

> Automatically compensates for the breathing demand of the user.

> The unit has a small cylinder of compressed oxygen. reducing and regulating valves abreathing bag, face piece, and a chemical container to remove carbon dioxide from the

exhaled breath.

Self - generating type

> It has a chemical canister that evolves oxygen and remove the exhaled carbon dioxide.

> It eliminates high - pressure cylinders.

Demand type

> Consist of high - pressure air cylinder, a demand regulator, a face piece and tube as-

sembly with an exhalation valve.

> In use wearer opens the cylinder valve after putting on the face inhales air at breathing

pressure.


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They should see that the edges of the valves are not curled and that valve seats are smooth

and clean. Inhalation and exhalation valves should be replaced periodically.

In addition to the daily check, respirators should be inspected weekly by trained persons.

During the weekly inspection, rubber parts should be stretched slightly for detection of finecracks. The rubber should be worked occasionally to prevent setting (one of the causes of

cracking) and the headband should be checked to be sure that the wearer has not stretched

it in an attempt to secure a snug fit (see Figure 17 - 23).

Cleaning and sanitizing

The actual cleaning may be done in a variety of ways.

The respiratory protection equipment should be dismantled and washed the detergent in

warm water using, a thoroughly rinsed in clean water , and then an dried in a clean place.

Care should be taken to prevent damage from rough handling. This method is an accepted

procedure for a small respirator program or where each worker cleans his or her own respira-

tor.

A standard domestic clothes washer may be used if a rack is installed to hold the face pieces

in a fixed position, (if the face pieces are placed loose in a washer, the agitator may damage

them.)

This method is especially useful in large programs where respirator usage is extensive.Steel , reinforced plastics and hard rubber are used for safety toes with the choice depending

on the protective level desired and the shoe design. The test requirements are identical for

both womens and mens shoes

Toe boxes used in shoes may be conductive, nonconductive, or spark resistant. For work

under wet conditions, rubber boots or rubber shoes may be obtained with a steel toe box to

protect against impact. Puncture - resistant soles are another feature.

TESTING OF PERSONAL PROTECTIVE EQUIPMENT

EYE PROTECTORS (IS 5983 - 1980)1. Non optical tests - stability at high temperature.

> Robustness : 22 gms steel balls are impinged from 1.3 mtr. length.

> Suitability for disinfection, corrosion and ultraviolet radiation.

> Protection against gas and dust.


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3. Sole : Oil resistance test - 2 to 3 min thick sole sample piece is taken and smoothened

by buffing. The peice is kept in a solvent mixture (85/15 - iso - octane to toluene ) for 24

hrs. Change in thickness should be in the range of - 5 to + 15%

Acid resistance test - sole sample piece is kept for 72 hrs each in H2SO4 30% HCI andNaOH solution, Difference in change in weight is measured ,which should be less than

2%.

industrial hygiene part1 paper v

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