Outline

I. Review Introduction
II. Work Environment Measure definition
of Workplace hazards
III.Type of Environmental Monitoring
IV.Example of Instruments for
Measurement
V.Applying Work Environment Measurement in
Confined Space
 I. Introduction
• Industrial hygiene is the science and art devoted
to the recognition, evaluation and control of
environment factors and stresses arising in or
from the workplace, which cause sickness,
impaired health and well being, or significant
discomfort and among workers or among citizens
of the community.
• Industrial hygiene is primarily concerned with the
control of occupational health hazards that arises
as a result of or during work.
II. Work Environment Measurement
• Evaluating occupational health and safety
hazards is achieved through work environment
measurement, analysis of the samples and
comparison of these results with established
standards.
• Work environment measurement refers to the
determination of environment stresses and their
hazardous effects on worker’s health through
direct measurement of hazards using industrial
hygiene equipment.
II. Work Environment Measurement

A review of Workplace Hazards

1. Chemical Hazard
2. Physical Hazard
3. Biological Hazard
4. Ergonomic Hazard
II. Work Environment Measurement

A review of Workplace Hazards

1. Chemical Hazards
• DUST
Any chemical that has been classified as •MIST
hazardous or for which relevant •FUMES
information exists to indicate that it is •GAS
hazardous. •VAPOR

2. Physical Hazards
• NOISE
Problems relating to such things as noise, •VIBRATION
vibration, temperature extremes, •TEMPERATURE EXTREMES
radiation, illumination and pressure •RADIATION
extremes. •ILLUMINATION
•PRESSURE EXTREMES
II. Work Environment Measurement
Cont. Workplace Hazards

3. Biological Hazards
• VIRUSES
Any virus, bacteria, fungus, parasite, or •BATERIUM
any living organism that can cause a •FUNGI
disease in human beings. They can be a •PARASITES
part of the total environment or •OTHER DISEASE-CAUSING
associated with certain occupations LIVING ORGANISM

4.Ergonomic Hazards
Multidisciplinary activity dealing with • IMPROPERLY DESIGNATED TOOLS
interactions between man and his total OR WORK AREA
working environment elements as •IMPROPER LIFTING
•POOR VISUAL CONDITION
atmosphere, heat, light and sound as well
•REPEATED MOTIONS IN AWKWARD
all tools and equipment in the workplace. POSITIONS
 III. Type of Environmental
Monitoring
• Monitoring is a continuing program of
observation, measurement and judgment, all
of which are necessary to recognize potential
hazards and to judge the adequacy of
protection.
• Monitoring requires an awareness of the
presence of potential hazards and an
assessment of continuing basis of the
adequacy of the control measures.
III. Type of Environmental Monitoring

Type of Environmental Monitoring

1. Personal / Breathing Zone Monitoring
• The measurement of a particular employee’s exposure to airborne,
contaminants.
•In personal monitoring, the measurement device or dosimeter, is placed
as possible to the contaminants’ entry portal to the body.
•When monitoring an air contaminant that is toxic if inhaled, the
measurement device is placed close to the breathing zone.

2. Area / environmental Monitoring

•The measurement of the contaminant concentrations in the workroom.
•The sampling device is placed in a fixed location in the work area that a generally
occupied by employees. This type of collection is also referred to as environmental
monitoring
 IV. Example of Instruments for
Measurements
• 1. Illumination
• 2. Noise
• 3. Chemical
• 4. Heat Stress
 IV. Example of Instruments for
Measurements
1. Illumination
The measurement of the
stream of light falling
on a surface
Lux – the unit of
measurement
• Luxmeter – a direct reading
instrument which contains
photo, light sensitive cell and
micrometers which can be
calibrated to read directly in lux
IV. Example of Instruments for Measurements

2. Noise
Sound and noise are often used interchangeably, but
generally, sound is descriptive of useful
communication or pleasant sounds such as music,
while noise is used to describe discord or unwanted
sound. Noise may be classified as continuous,
intermittent and impact.
Decibel – a dimensionless unit related to the logarithm
of the ratio of a measurement quantity to a
reference quantity.
Frequency – describes the rate at which complete cycles
of high and low pressure regions produced by the
sound source
IV. Example of Instruments for Measurements
Cont. NOISE

• Sound Level Meter – the instrument

which measures the root-mean-square
(rms) sound pressure level in decibels,
which is proportional to intensity or
sound energy flow. Consists of a
microphone, an amplifier with
calibrated volume control and an
indicating meter.
IV. Example of Instruments for Measurements
Cont. NOISE

Impulse Meter
The special instrument
which measures the
peak levels of noises
which lasts a fraction of
a second such as those
produced by hammer
blows or punch press
strokes
IV. Example of Instruments for Measurements
Cont. NOISE

Frequency Analyzer
The instrument which
measures the frequency
distribution of the
sound energy
IV. Example of Instruments for Measurements
Cont. NOISE

Sound Monitor
Statistical analyzers
developed to assist in
indicating the
percentage of time that
the sound level lies in
certain predetermined
level ranges
IV. Example of Instruments for Measurements

3. Chemical (Common Groups)

IV. Example of Instruments for Measurements
Cont. 3. Chemical

3.1 Direct Reading Instruments

- Single Chemical Instrument
- General Survey Instrument
- Based on Color Change
3.2 Indirect / Integrated Air
Sampling Instruments
IV. Example of Instruments for Measurements
Cont. 3. Chemical

3.1 Direct Reading Instruments

3.1.1 Single Chemical Instruments
• Designed to specifically monitor for a single
chemical
Examples:
• O2 monitors
• CO2 Monitors
• Etc.
IV. Example of Instruments for Measurements
Cont. 3. Chemical- 3.1 Direct Reading Instruments

3.1.2 General Survey Instruments

– Capable of detecting a large number of
contaminants but generally cannot
distinguish them
Example:
• Combustible gas indicator
• Explosimeters
• Photo ionization detectors
• Etc.
IV. Example of Instruments for Measurements

explosimeters

Combustible gas indicator

Photo ionization
detectors
IV. Example of Instruments for Measurements
Cont. 3. Chemical- 3.1 Direct Reading Instruments

3.1.3 Based on Color Change

• Sampling media that change color when

contaminated air is pulled through them, and
can provide the ability to do direct reading
measurements for a wide variety of gases and
vapors
Examples
• Detector tubes
IV. Example of Instruments for Measurements Cont. 3. Chemical-

3.2 Indirect / Integrated Air Sampling Instruments

3.2.1 Liquid Media Samplers
• Devices which use an absorbing liquid to capture
gaseous substances
Example: Bubblers, Impingers, etc.
3.2.2 Solid Sorbent Sampling
• A pump is used to pull air through the sorbent
wherein the sampling media may be charcoal,
silica gel, etc.
3.2.3 Passive Monitors
• Instruments used to monitor gases and vapors
and may be used relatively unattended
IV. Example of Instruments for Measurements Cont. 3. Chemical-

4.0 HEAT STRESS

• The excessive heat load • Globe, Wet and dry
and is the aggregate of bulb
environmental and • Thermometers
physical work factors
that constitute the total
heat load imposed on
the body
 CONFINED SPACE
An area is a confined space if:
1.It has limited openings for entrance
and exit
2.It has unfavourable natural
ventilation; and
3.It is not designed for continuous
worker occupancy
 1. Limited Openings for Entry
and Exit
Opening Size Opening Location
• Confined space openings can be • Some confined spaces have
as small as 18” in diameter. very large openings, as in
• This provides difficulty for open-topped spaces such as
entrance and exit of worker.
pits, degreasers, and
• Small openings also make it
difficult to get needed equipment
excavation.
in and out of the space-especially • However, access to these
protective equipment such as spaces may require the use
respirators to be used when of ladders, hoist, and other
entering hazardous atmosphere,
and life-saving equipment in the
equipment, presenting
event when rescue is needed difficulty of escape during
emergency situation
 2. Unfavorable Natural
Ventillation
• Ambient air contents 78% nitrogen, 21 % oxygen, and traces of
other gases.
• Inside a confined space, natural ventilation is very different
from ambient air, mainly because air is not able to freely move
in and out of the space.
• This poses a danger of having hazardous gases trapped inside
the space, especially when it is used to store chemicals and
organic substances that may decompose.
• Another danger is that this space may not have enough oxygen
to support life, or it may contain so much oxygen that it poses
a very high potential for fire or explosion when an ignition
source is introduced into the space.
 3. Not designed for Continuous
worker Occupancy
• Normally, confined spaces are designated to store a product,
enclose materials and processes, or transport products or
substances.
• In short, these confined spaces have not been designed for a
worker to regularly enter and perform work inside.
• Occasional worker entry is done in order to perform
inspections, maintenance, repair, cleanup, and other similar
tasks.
• The nature of work to be done inside confined spaces is usually
difficult and dangerous, mainly because of the chemical and
physical hazards that may be present inside the space
Example of Confined Space
 Examples of Confined Space
• Boilers • Septic Tank
• Furnace • Sewage Digester
• Pipeline • Sewer
• Pit • Silo
• Pumping Station • Storage Tank
• Reaction or Process • Utility Vault
Vessel • Vat (storage bin,tub)

It should be noted that the presence of a confined space in a work area can
Complicate working in and around these spaces, as well as make rescue operations
Difficult during emergency situations . It is necessary then, that one identifies all
Hazards present in these confined spaces.
 HAZARDS IN CONFINED SPACE
1. Temperature extremes
Extremely hot (as when the space has been
steamed) or cold temperature inside a space
presents problems to workers.
2. Engulfment hazards
This is present when loose, granular materials ( e.g.
Grain, sand, coal) are stored inside the space (e.g.
Bins and hoppers). These materials can crust or
bridge over a bin and break loose under the weight
of the worker, resulting in the worker being
engulfed and suffocated to death.
HAZARDS IN CONFINED SPACE

3. Noise
Because of the design and acoustic properties of the
space, noise has a tendency to be amplified. Aside
from posing hearing hazards, too much noise may
also cause a warning shout to go unheard.
4. Slick / wet surface
Wet surface increase the probability of causing slips
and falls, whose effects range from minor injuries to
permanent disability, even death. Also, having wet
surfaces increase the danger (both in terms of
likelihood and effect) of electrocution whenever
electrical equipment are used for the task.
HAZARDS IN CONFINED SPACE

5. Falling objects
This is especially true for workers who work in
spaces that have topside openings for
entry/exit, and/or have work being done
above them.
 HAZARDOUS ATMOSPERE
Hazardous atmospheres are those that may
expose workers to the risk of death,
incapacitation, impairment of self-rescue, injury
or acute illness.
1.Oxygen-deficient atmosphere
2.Combustible / flammable atmosphere
3.Toxic atmosphere
HAZARDOUS ATMOSPERE
1. Oxygen-deficient atmosphere
Oxygen Scale
23.5% Oxygen –enriched environment
21.0% Ambient air
19.5% Minimum requirement for entry in
confined spaces
16% Impaired judgment and Breathing
14% Faulty judgment and rapid fatigue
6% Difficulty in breathing
Death in minutes
Cont. 1. Oxygen-deficient atmosphere

Common reasons for the decrease

of oxygen level in confined spaces:
Consumption of oxygen
 Welding, cutting, brazing and other similar tasks
( combustion)
 Rusting
 Bacterial action (fermentation)
 Presence of living organism, e.g. Moss, etc.
(respiration)
 Presence of decaying organism (decomposition)
Cont..1. Oxygen-deficient atmosphere
Cont. Common reason.......

 Displacement of oxygen

 Gases have varying weights, and

displace one another, resulting in the
heavier gases settling at the bottom of
the space, and the lighter ones on top.
HAZARDOUS ATMOSPERE
2. Combustible/Flammable
atmosphere
The Fire Triangle
Oxygen
Fuel
Source of Ignition
 An atmosphere become flammable when it
contains a proper mixture of oxygen and fuel
(flammable gases, vapors, dust). The introduction
of an ignition source (e.g. Sparking or electrical
tool) into this kind of atmosphere will result to an
explosion
Cont. 2. Combustible/Flammable atmosphere

NEVER USE PURE OXYGEN

TO VENTILATE A CONFINED
SPACE.
Oxygen-enriched environments
will cause flammable materials
to burn violently when ignited
HAZARDOUS ATMOSPERE

3. Toxic Atmosphere
Toxic substances in confined spaces usually
come from:
 Product Stored in the space
Some products stored in confined spaces are
absorbed into the walls, or give off toxic gases
when removed, or when cleaning out the
residue of the stored product.
Common example is when sludge is removed
from a tank. The decomposed material gives
off hydrogen sulphide gas.
Cont. 3. Toxic Atmosphere
 Type of work done in the space
• Toxic atmospheres are generated by
chemicals, substances, and processes used
during the confined spaced work.
• As in tank cleaning, the solvent used for
this type of work can be very toxic in confined
spaced.
 Areas surrounding the space
• Toxic materials produced in areas surrounding
the confined space can enter and accumulate in
the confined space.
 WILD CARD

W
A
L
K
G I
N

Jay Walking
Maslow
 ATMOSPHERIC TESTING
 What to Test
1. Test for oxygen first
 It is recommended that oxygen levels be tested
first, to know whether one has sufficient
breathing air when entering the confined space.
 When oxygen levels are below 19.5%, it signifies
that the confined space has to be well-ventilated
prior to entry (and consequently re-tested after
ventilation), or the worker has to have a self-
contained breathing apparatus (SCBA)
 When oxygen levels fall within normal level,
or exceed normal level ( in an oxygen-
enriched environment), although this signifies
that the worker will probably have enough
oxygen, it should be noted that the presence
of enough oxygen is also one of the key
factors to a combustible/flammable
environment. Thus, there is a need to.......
 2. Test for Combustible gases
 This is to ensure that although oxygen is
present, there is no danger of explosion
(either there is no combustible gas present,
or combustible gases are present but at levels
are below).
3. Test for toxic gases
 After detecting oxygen and combustible gas
levels in the confined space, toxic gas levels
should also be identified.
 How to test:
 It is important to keep in mind that some
gases and vapors are heavier than air, while
some are lighter than air. Applying the Law of
Gravity, heavier gasses will tend to settle at
the bottom of the confined space, while the
lighter ones will be displaced to the top of the
confined space
 It is then key that when doing atmospheric
testing, one should do test all areas (stratified
air sampling) – starting from top, then the
middle, then the bottom of a confined space.
• METHANE
(lighter than air)

CARBON MONOXIDE
(slightly lighter than
air)

HYDROGEN
SULFHIDE
(heavier than air)
 IT IS RECOMMENDED THAT IN
DOING STRATIFIED AIR
SAMPLING,
One should apply the 2 by 2
principle*, wherein one should test
for a duration of at least 2 seconds
at 2 feet intervals.
* This is dependent on the gas monitoring equipment used. It is
best to read the user’s manual of your gas monitor prior to use
 GAS MONITORING
 While it is very important to detect the types
and levels of gases present inside confined
spaces prior to entry, it is as important that
one continuously monitors gas levels in the
entire duration of the confined space activity
 One must always remember that whatever
activity done inside the confined space can
alter the mixture of air inside.
 Any or a combination of the following can
happen:
Consume oxygen (and decrease oxygen level)
Displace Oxygen
Generate a combustible environment and
cause an explosion (an ignition source
introduced into a combustible environment)
Release toxic gases
One can only ensure that he is in a “SAFE”
environment if he continuously monitors his
work environment.
NEVER TRUST YOUR SENSES TO
DETERMINE IF THE AIR INSIDE A
CONFINED SPACE IS SAFE!
 Many gases and vapors cannot be seen or smelled.
Some can be initially smelled, but can desensitize
olfactory faculties at prolonged exposure.
 More importantly, oxygen levels cannot be
determined by a person, unless one experiences its
effects
 TYPES OF GAS MONITORS

1. Fixed Systems
Remote Sensors
Audible/Visual Alarms
Control Panels
Power Supplies
2. Portable Gas Monitors

 Single Gas Monitors

Multiple Gas Monitors

 Points to consider when selecting
Gas Monitoring
 Size  Ease of calibration
 Durability  Training
 Cost  Intrinsic safety
 Ease of use  Sample draw capability
 Ease of maintenance

Gas Detection with a Properly

Calibrated Instrument is the
ONLY SURE WAY OF KNOWING
IF DANGEROUS GASES ARE PRESENT