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									   Environment means the physical surrounding
    condition, circumstances etc in which a
    person lives.
   Work place means a place at which a person
   Monitoring means a device of checking or
    warning about a situation, operation etc.
   Today, India is among the ten most
    Industrialized Nations in the world. For the
    increase in the sophistication and
    modernization, the industry may generate
    inherent     hazards     associated     with
    hazardous processes/ operations. The
    industrial processes/ operations need to
    be evaluated and controlled by using
    sophisticated monitoring techniques
   The evaluation of the magnitude of the hazards
    is done by quantitative measurement of the
    chemicals and/or biological parameters at
    workplace environment. In India, the Factories
    (Amendment) Act, 1987, under Section 41-F,
    requires compliance in keeping the levels of
    airborne chemicals at the workplace, below
    their Permissible Limits of Exposure. This
    requires a comprehensive policy and planning
    towards the assessment of airborne levels of
    chemicals which, in addition, helps achieve the
    target of continual improvement in the work
Environmental and Occupational
Hygiene means :

Anticipation of Hazard
To recognize hazard
Evaluation of hazard
Control of hazard
   Anticipating (possible) risk or potential
    problem, and then eliminating or reducing
    that risk, is perhaps the major function of the
    industrial hygienist and one in which
    experience plays an important role. Industrial
   Workplace hazards fall into four major
   Chemical Hazards
   Physical Hazards
   Ergonomic Hazards
   Biological Hazards
Gases & Vapours    Aerosols
 Gas             Dust
 Vapour          Fume
   A gas is a chemical substance whose
    molecules are moving freely within a space
    in which they are confined (e.g., cylinder) at
    normal temperature and pressure.
   Gases assume no shape or volume.
   Follow laws of diffusion.
   Examples : SO2, CO, H2S, etc.
 A vapor is the gaseous phase of a liquid or
  a solid
 The amount of vapour given off by a
  chemical substance is expressed as the
  vapor pressure and is a function of
  temperature and pressure.

   Examples : Vapours of Benzene, Toluene,
   An aerosol is a suspension of solid
    particles or liquid droplets in a gaseous
   Aerosols may be characterized by their
    aerodynamic behavior and the site(s) of
    deposition in the human respiratory
   Solid particles generated by handling,
    crushing, grinding, rapid impact,
    detonation and decrepitation of organic or
    inorganic materials.
   Do not flocculate, except under electrostatic
   Do not diffuse in air but settle down under
    the influence of gravity.
   Particles range from 0.1 to 100 µ in
   Example : dusts of metals, silica, etc.
   Minute solid particles that range from
    0.0002 to 0.1 µ in diameter.
   Generated by sublimation or condensation
    accompanied by a chemical reaction, such
    as oxidation.
   Examples : Fumes of Lead, Zinc, etc.
   Carbon or soot particles less than 0.1 µ in
   Result from incomplete combustion of
    carbonaceous materials such as coal.
   Generally contains droplets, as well as dry
 Particle which have defined length to width ratio.
 Examples : Asbestos, Fibrous Glass, Cellulose
   Suspended liquid droplets
   Generated by (i) condensation from gaseous
    to liquid state Or
    (ii) breaking up a liquid into a dispersed
    state, such as splashing, foaming and
 Fog is dispersed water drops
 Can be viewed as clouds that are in contact
  with the Earth’s surface
 Fogs are created during cooling of air next
  to the Earth’s surface by radiation to space
  (radiation fogs) or by a contact with a
  surface (advection fogs)
Air pollution in large industrial cities or urban
    regions is called smog.
Term “smog” derived from “smoke” & “fog”
Types of smog-
1.  Sulphurous smog
2.  Photochemical smog
1.   Sulphurous smog: results from a high
     concentration of sulphur oxides (SOX) in
     the air, caused by burning of sulphur
     bearing fossil fuels, particularly coal.
2.   Photochemical smog: results from nitrogen
     oxides & hydrocarbon vapours emitted by
     automobiles and other sources, which
     then undergo photochemical reactions in
     the lower atmosphere.
    Hazard in occupational as well as community
     environment can be due to physical factor and
     chemical factor
    Physical Factors or Hazards:-
1.   Noise – unwanted sound
2.   Temperature – either high or low extremes
3.   Illumination – level of intensity
4.   Vibration – motion condition
5.   Radiation –(Ionizing) Cell clam-aging
6.   Radiation – (Electromagnetic) heat producing
7.   Pressure – atmospheric either high or low
   Measurement and quantification of physical
    and chemical stressors in any operation is a
    key step in safeguarding the health and
    safety of workers. For every hazard, the
    industrial hygienist refers to the relevant
    standards.   The    legal   standards    are
    Permissible Limits Exposure (PLE) as given
    in the Factories Act, 1948. The American
    Conference of Governmental Industrial
    Hygienists (ACGIH), USA, also recommends
    Threshold Limit Values for Chemical
    Substances and Physical Agents.
 Inhalation :
 Causes  90% occupational diseases
 Surface area of lung tissue is 55 to
  75 m2
 8-10 m3 of air is breathed by an
  average man during 8 hours
 Respiratory system is the portal of
 Skin absorption:
 Causes  9% occupational
 Surface area of skin is only 2
 Skin serves as the portal of
 Causes  1% occupational
 Mouth & digestive system
  serves as portal of entry
    The important points to be considered for
     environmental monitoring are :
1.   Purpose of Sampling
2.   Preliminary Survey
3.   Sampling Strategies
4.   Sampling Equipments
    Sampling & Analytical Techniques
5.   Air Sampling Analytical Equipment –Guidelines
6.   Interpretation of Results
7.   Benefits of Environmental Monitoring
1.   Purpose of Sampling

-    To determine levels of exposure among workmen
     to various atmospheric contaminants.

-    To determine the effectiveness of control

-    To investigate complaints.

-    For research purpose.
2.   Preliminary Survey

     The first step in evaluating the occupational
     environment is to conduct preliminary survey.
     The preliminary Survey Includes:

-    Study work operation and process obtain full
     details of the nature of work materials and
     equipment used or adopted, products and by
     products, control measures, no. of employees,
     sex, hours of work and housekeeping.

-    Study the substance for physio-chemical
     properties, toxicity, route of entry, continuity of
     exposure and quantity involved, Individual
     susceptibility and Threshold Limit Values.

-    Statutory   provisions    pertaining     to    the
3. Sampling Strategies
  The following basic questions must be answered
  to implements the correct sampling strategy.
  a) Where to sample – Locations
  b) How long to sample – Duration
  c) How many samples – number
  d) When to sample – Covering typical operation
    ( day or night, what month or season)
Samples are usually collected in the following

i) At the breathing zone of the workers
ii) In the general atmosphere at the room,
iii) At an operation it self.
  The factors which determine the duration
the sampling or volume at the air to be
sampled as follows:-
i) Sensitivity of the analytical procedure.
ii) The Threshold Limit Value (TLV) /
Permissible Exposure Limit (PEL) of the
particular Contaminant and
iii) The expected air concentration.
 The number of samples to be collected
depends on the purpose of sampling.
The sampling should be carried out
throughout the shift during work operation.
Generally a minimum 4 to 5 samples may be
necessary to indicate exposure for a certain
task or cycle of operations.
   Type of sampling to be used depending
    upon a number of factors
    - The perpose pf sampling
    - the equipments available
    - The environmental condition
    - The nature of toxic contaminants
   -   Personal sampling
   -   Area sampling
   -   Grab sampling
   -   Integrated sampling
   -   Direct reading
   Personal air sampling is the method of
    evaluating worker’s exposure to air
    contaminants. It involves the collection of an
    air sample by sample device worn by the
    worker. The sampling device is positioned as
    close as possible to the breathing zone of the
Personal Monitoring
 Personal monitoring should be used to
 evaluate the risk of exposure to the
 individual worker. Air sample should be
 collected in the workers breathing zone by
 means of personal samplers and sampling
 should be carried out while the work activity
 is in operation throughout the work shift so
 as to compare to occupational exposure
 limit values, which are usually quoted for an
 eight hour period or for short term limits,
 15 minutes personal sampling where
 concentrations vary from one work
 operations or phase to another, should be
 done in such manner that the average level
 of exposure of each individual worker can
 be determined.
   Area sampling or general room air sample are
    taken at fixed location in the workplace. It is
    used mainly to pinpoint high exposure areas.
   Grab sampling is the collection of an air
    sample over a short poriod. Grab samples
    represent the environmental concentration at
    a particular point in time. It is used for
    evaluating peak exposures.
   Integrated sampling is the collection of an air
    sample for longer period. In integrated air
    sampling a known volume of air is passed
    through     a   collection   media     to    the
    contaminant from the sampled air stream. It
    is the preferred method of determining time-
    weighted-average         (TWA)        exposure.
    Integrated sampling consist of one or a series
    of samples taken for full or partial duration of
    the time averaging period
   Direct reading and vapour monitor are
    analytical instruments with rapid response
    time. They are defined as devices in which
    sampling and analysis are carried out within
    the instruments. Direc reading devices can
    be portable instruments or fixed site
   The instruments are used for preliminary
    evaluation (to locate the source of hazardous
Biological Monitoring

Biological monitoring involves the measurement of
the chemical or its metabolite in the biological
agents such as, Urine, Enzymes, Exhaled breath
Body tissues and body fluids and then comparing
the levels with accepted values as per the Standard
reference. The selection of biological agent for test
mainly depends on the characteristics of the
chemicals to be studied. The number of chemicals
for which biological monitoring has become
available has increased in recent years, but is still
small compared with the number of chemicals used
in the industry. The biological monitoring is well
recognized in the recent years for evaluating the
worker exposure to hazardous chemicals.
    Selection of equipments depends upon the
    number of factors
-   Sampling objective      - cost
-   The physical and chemical    - reliable
     nature of contaminants - duration
-   Presence of other chemicals
-   Type of sample needed
   Air sampling basically consist of three
    elements :

   1 – Suction device

   2 – Flow rate indicator

   3 – Trapping device
a) Suction Device : which may be an electrically,
     driven pump or hand operated/pump Squeeze
     bulb or aspiratory bottle.
b)    Flow Rate indicator : Flow meter or Rotameter to
     indicate the rate of suction of air to calculate the
     amount of air sampled.
     The flow-meter attached to equipment must be
     calibrated with primary standards as soap bubble
c)   Trapping Device : It should be able to efficiently
     retain the contaminants to be sampled by
     absorption, adsorption, chemical reaction or
     mechanical retention.
 The contaminants can be classified into two
1 – Particulate matters :
      - Dust, fumes and mist
2 – Gaseous matters
       - Gases and vaours
  The gaseous matters are again classified
  into three groups
 Gaseous and vapours which are soluble or
  miscible in water – can be collected in water
 Gaseous and vapours which are insoluble in
  water but are soluble in other solvents or
 Gaseous and vapours which are not soluble
  in water but adsorb in other agents.
   Particulate matter : Filter papers
    ◦ Membrane filter paper, Glass fiber filler paper
   Gaseous : Absorbing medium
     - Impinger tube
   Vapours : Adsorbing medium
    - Charcoal tube, Silica gel tube
Collection Media : The physical form of the
contaminant determines the type of medium that
the sample is collected on. Thus, there is set of
media for gases and vapours and another
grouping for particulates.
Gases & Vapours : Gases and vapours are
collected using liquid media samplers, Solid
sorbent tubes.
           Liquid Media Sampler

Gas Wash Bottle or Midget Impinger Tube
Liquid Media Sampler
There are two types of dusts :
1. Total dust : It contains respirable and non-
   respirable dust

2. Respirable dust : The size of the dust particle
    is less than 10 micron
   Organic solvents
    ◦ Benxene, Tolune, Xylene etc.
    ◦ Collected in activated charcoal tubes
    Inorganic solvents
    - Alcohols, eaters, etc.
    - Collected in activated silica gel tubes
Non-fibrogenic Dusts
    Nuisance Dust
   No significant organic disease or toxic effect
   Unpleasant deposits in eyes, ears and nasal
    Toxic Dusts
   Produce systemic poisoning e.g. Lead,
    Arsenic, Cadmium, Manganese.

Thoracic - 10μ

Respirable - 4μ
             Relative size of particles

                                         Respirable dust
                                           4 micron
                                          Thoracic dust
                                           10 micron
                                         Inhalable dust
             INHALABLE                    100 micron

      1 4        7       10   30   100
   Sampling for the particulate:
    The particulates are classified according to
    their physical state i.e. liquid and solid
    liquid particles are usually classified as
    mists but if the size is smaller they are
    termed as fog solids are categorized as
    dust, fumes and smokers. Dust are termed
    as formed through. Some mechanical
    process such as crushing, drilling and
    grinding. Fumes are formed by combustion
    sublimation or condensation processes and
    the term is generally applied to metal
    oxides of zinc, magnesium, iron, lead and
    others. Smoke is generated as result of
    combustion of organic material.
        Particulates are collected     on filter
    To determine the concentration of airborne
    dust by gravimetric method.
A sampling cyclone such as this is
used to sample for the respirable
fraction of airborne particulate. The
air enters the inlet, then passes
through the vortex-like separator,
which removes larger particles from
the air stream. The smaller
particles are then collected of the
filter inside the holder.
   Gravimetric
   Adsorption-charcoal or silica tubes
    Analysed on Gas Chromatograph(GLC) or
    High pressure liquid cromatograph(HPLC)
   Absorption-impinger tubes or fritted bubbler
    Analysed by colorimetric methods
   Evaluation and control of chemical exposure
    in the workplace are major components of an
    effective   safety   and    health   program.
    Workplace controls at the source of chemical
    release are inherently better than controls at
    the worker, such as personal protective
    equipment. To minimize the exposure to
    various airborne contaminants encountered in
    industries, one or more of the following
    control methods of control may be applied:
   Occupational Hazards in an industry can be
    controlled by following measures.

   1. Engineering Control Measures.
   2. Administrative Controls
   3. Personal Protective Equipment
   Control methods can be applied at three

   Control at Source

   Control in Air path

   Control at Receiver
   Substitution with a less harmful materials
   Change of process eg. Airless paint spraying
   Enclosure of process
   Isolation of process (physical barriers)\
   Wet method
   Local exhaust ventilation
   Adequate maintenance programme
   Housekeeping
   General exhaust ventilation
   Dilution ventilation (supplied air)
   Increase distance between Source and
    receiver (Semi automatic or remote control)
   Continuous area monitoring (pre set alarm
   Training and Education
   Rotation of workers
   Enclosure of workers
   Personal monitoring device
   Adequate maintenance programmes
   JOB ROTATION reduces the amount of
    exposure to hazardous agents per
    employee. However, it may increase the
    number of employees exposed
    knowledge of hazards of chemicals handled
    and preventive measures
   WORK PRACTICES-house keeping, waste
    disposal procedures, personal hygiene, etc.
   Air sampling analytical equipment –
    The analytical methods used to determine the
    concentration of the desired contaminant Include
    Chemical Methods:

    Colorimetric : The principle of this method is the
    development at the colour by a reagent which is
    indicative of the concentration of the substance to
    be analyzed Examples of these methods are
    determination of zinc, lead, mercury etc. by
    dithizone extraction. Ammonia, Chlorine, Sulphure
    dioxide, Nitrogen di oxide etc.
Gravimetric : This method depends on the formation
 of precipitate or a residue which can be weighed
 Example is analysis of dust samples for free silica.
Volumetric : By the use of standard solution for
 titration Example are acid gases which are titrated
 with a basic reagent.
Physical Method : The Physical methods widely used
 for the determination of the various contaminants
 are emission spectroscopy Infra red and Ultraviolet
 Spectroscopy mass spectroscopy, paleography, X-
 ray, diffraction and gas chromatography. High
 pressure liquid chromatography etc.
Interpretation of data
The data obtained can be interpreted for the following:-
i)   Interpret results of the examination of the work
     environment in terms of ability to impair health. Nature of
     health impairment, workers efficiency and present specific
     conclusions to the management and authorities.
ii)  Make specific recommendations for the effective control
     preventive measures.
iii) Prepare rules, regulations, standards, guidelines etc. form
     the finding of survey.
iv)  Conduct programmes for the education of workers and
     management on the prevention and control of occupational
     work environment.
v) Based on the findings conduct epidemiologic
  studies of workers in industries to discover
  possibilities at the presence of occupational
- Improve employees health/hygiene

- Improve job satisfaction

- Improve productivity

- Improve employees attitude towards management

- Opportunity for the company to provide technical
  input data in relation to regulations and standards.
(ii) Fumes: There are solid particles generated by
condensation, generally after volatilization from
melted substance and often accompanied by
oxidation. The particles size is usually less than o.2
micron. Common examples are lead Zinc is fumes.
(iii) Mists: Dispersion of liquid particulates in air.
These are generally formed by the condensation of
water vapour on sub-microscopic particles or by
the atomization of liquids. Mist of Sulphuric Acid is
an example of this dispersion.
    Chemical Factors or Hazards:
1.   Gases & Vapours – Common Examples are:
     Sulphur dioxide, Carbon monoxide, Hydrogen
     cyanide gases, and the Vapours of Trichloro
     Ethylene, Benzene, Xylene etc.
2.   Particulate –
     (i) Dusts :- There are solid particles produced by
     grinding, crushing, drilling and blasting
     operations and are suspended in the air. The
     sizes of the particles are predominantly higher
     than o.2 micron

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