INDUSTRIAL HYGIENE
Fundamentals of industrial hygiene
Updated December 2010
- Information provided subject to the 'Conditions for Sharing Materials and Advice' -
Objective

To learn about industrial hygiene

To define the subject and scope of industrial hygiene

To understand about occupational exposure limits (OEL)

To learn what occupational diseases are and how to
prevent them.

To know what engineering controls can be implemented
2
Industrial hygiene

Definition Industrial Hygiene: (Fundamentals of IH, 4th
edition)
“Industrial hygiene is that science and art devoted to the
anticipation, recognition, evaluation and control of those
environmental factors or stresses arising in or from the
workplace that may cause sickness, impaired health and
well-being, or significant discomfort among workers or
among citizens of the community”
(AIHA 1994-1995 Membership Directory)
3
Industrial Hygiene

Industrial Hygiene is the art and science of the
anticipation, recognition, evaluation, and control of
environmental health hazards arising in or from the
workplace.

Safety = prevention of accidents / incidents
IH = prevention of occupational illnesses

4
Fundamentals of Industrial Hygiene
Respect hierarchy
of controls
Evaluation
Control
Theoretical assessment of
exposure
Measurement strategy
Monitoring
Evaluation results
Report
Basics
IH
Identification
Identification of risks
5
Fundamentals of Industrial Hygiene
Chemical agents
• gases & vapors
• dust = API & IPI
Physical agents
• noise & vibration
• IR & NIR
• climate
Biological agents
(Ergonomics)
• repetition
• posture
• workforce
• bio hazards
• fungi
• allergens
• toxins
6
Chemical Hazards

Dusts

Mists

Fumes

Vapors

Gases
7
Physical Hazards

Noise

Vibrations

Radiation
– Ionizing radiation : Alpha-Beta-Gamma
– Non-ionizing radiation : UV-light, visible light,
infrared, radio waves, microwaves
8
Biological Hazards

Viruses

Fungi or Molds

Bacteria

Plants

Insects

Animals
9
Occupational diseases & IH

Exposure to chemical, physical or biological hazards can
cause occupational diseases.

Occupational diseases are acute or chronic (gradual or
delayed) reactions and are very diverse.

To avoid occupational diseases the exposure should be
prohibited, regulated, restricted, limited or controlled by
industrial hygiene practices & IH-programs.
10
Occupational health hazards



Immediate or acute reactions, like shortness of breath
or nausea, can be caused by a one-time event, (e.g., a
chemical spill) (usually no permanent reactions).
Gradual reactions, like asthma or dermatitis (skin
rashes), can get worse and persist when there is
exposure over longer periods (reactions tend to last for a
longer time).
Delayed reactions or diseases that take a long time
to develop, like lung cancer or loss of hearing, can be
caused by long-term exposure. These reactions can be
noticed long after the job is over.
11
Occupational diseases
Occupational diseases can be very diverse;









Acute poisoning
Occupational cancer
Chronic poison
Interstitial lung disease
Skin disease
Hearing loss
Muscular disorders
Lower-back morbidity and trauma of the spine
…
12
CHEMICAL HAZARDS
Hazardous substances

Hazardous substances are substances that can
have a harmful effect on health

Examples:
– Chemicals - organic solvents, acids,
pharmaceutical ingredients…
– Dust - metal dust, wood dust, flour…
– Fumes - welding, soldering…
– Fibers - asbestos
14
Hazardous substances can enter the body
inhalation
dermal
ingestion
15
Type of Health Effects
Acute effects –
immediate reaction
Chronic effects –
develop over years
16
Toxicity or poisoning
Response
All substances are toxic, there is not one that is not toxic.
The doses is the difference between a poison and a medicine.
Paracelsus (1493-1541)
Doses
= the intrinsic possibility of a chemical substance to
cause irreversible effects into a biological system
17
Potency of Hazardous Substances
Snake poison – xx can kill
Alcohol
xx gives effect
Xx leads to liver disease
We need xx mg/m3 to
live
18
Describing the hazard
We need to know how much of a hazardous substance a worker
can breathe without harm
This is given by the
Occupational Exposure Limit
OEL
19
Occupational Exposure Limits
The OEL is the concentration in the
air to which nearly all workers may
be repeatedly exposed day after day
without adverse health effects to
themselves or their children.
Termed Threshold Limit Value TLV by
ACGIH
(ACGIH is an American organisation for industrial hygiene)
20
Variation of exposure with time
Exposure patterns vary
Shift durations vary
To compare exposures for different situations,
we need a reference period
21
OEL reference periods
1.
8 hour reference period –ACGIH descriptor TLV-TWA – The 8
hour TWA exposure to which it is believed that nearly all
workers may be repeatedly exposed, day after day, for a
working lifetime, without adverse effect
2.
15 minute reference period – called Short Term Exposure
Limit (STEL)- The 15 minute TWA exposure that should not
be exceeded at any time during a work day, even if the 8 hour
TWA is within the TLV-TWA. Exposures (re. 15 mins) above
the TLV-TWA but below the TLV-STEL should not occur more
than 4 times a day, with 60 minutes at least between
successive exposures
3.
Ceiling (TLV-C) – the concentration that should not be
exceeded during any part of the working exposure
22
Who assigns Occupational Exposure Limits?
Who assigns OELs?
For common hazardous substances
1.
2.
Your national health and safety authority
ACGIH (called Threshold Limit Value, TLV)
For pharmaceutical ingredients
1.
J&J corporate toxicologists
23
ACGIH TLV’s
Order from www.acgih.org
The OEL set by your health and
safety authority and ACGIH
might be different
USE THE LOWER OEL
24
Examples of OEL’s set by ACGIH (values 2007)
Hazardous substance
Threshold Limit Value
TLV
8 hour
15 minute
Isopropyl alcohol
200ppm
400ppm
Benzene
0.5ppm
2.5ppm
Ammonia
25ppm
35ppm
-
C 0.1ppm
10 mg/m3
-
Acrolein
Particles not otherwise
specified
Cobalt
0.02 mg/m3
An instantaneous
-ceiling value that should
not be exceeded
Source: ACGIH 2007
25
Concentration Units
As mass in unit volume
1 mg /m3 is 1 mg in a cubic meter
1m
1m
1 μg /m3 is 1 μg in a cubic meter
1000 μg /m3 = 1 mg/m3
As the proportion of molecules
1m
1 ppm is one part (molecule) in a million
1ppb is one part in a billion
1000 ppb = 1 ppm
26
Setting an OEL – what to consider

Sources of information
– Animal studies
– Pharmaceutical trials
These indicate the lowest active dose, or the dose where
there is no observed adverse effect

Things that influence the effect on the body
–
–
–
–
–
Amount you breath in (10 m3 per day)
Body weight
How long the chemical stays in the body
Amount absorbed by body
Any hazardous substances formed in the body
27
Setting an OEL – how it is calculated
LAD (mg/kg/day) * BW
OEL = ---------------------------------------------------
V*T*SF*a
LAD
BW
V
T
SF
a%
lowest active dose
body weight (50 kg)
volume inhaled air (10 m3)
time, in days, to reach steady state in plasma
safety factor
absorption (assumed = 100%)
28
Typical Notes given with OEL’s




If carcinogenic, mutagenic or reproductive toxin
Skin: Substances which have the capacity to penetrate
intact skin
Sensitization: where skin or respiratory sensitization
could occur (that is, where intense response occurs to
low concentrations after a person has become
sensitised)
BEI: if a biological exposure index has been
recommended for the substance
29
Acceptable Surface Limits

A surface limit is sometimes set. It is helpful :
– if there might be significant exposure through the skin
– if potent substances might be re-suspended and inhaled
– to indicate contamination of surfaces
30
Acceptable Surface Limits
Acceptable Surface Limit
OEL




The ASL is the acceptable mass on
a specified surface area
(typically 10 x 10 cm, the area of
palms of hand)
Often set at 10 times the OEL for an
area of 100cm2
Not as frequently used as OEL
Not set by ACGIH for any substance
31
What to do with the OEL and ASL…

Compare the results from your exposure monitoring
surveys with the OEL to check if the exposure is OK

If you use Respiratory Protection Equipment, compare
the calculated exposure inside the mask with the OEL to
check if the effective exposure is OK

Compare the measured surface concentration with the
ASL to check that surface contamination levels are OK
32
Evaluate exposure by comparing measured TWA exposure
with OEL
Exposure
exceeds OEL
140%
130%
120%
Exposure as % of OEL
110%
100%
TWA as % of OEL
90%
80%
70%
60%
50%
40%
30%
20%
Exposure well
below OEL
10%
0%
33
Cumulative effect
Exposure to different substances or mixtures = rule of cumulative effect
= S Cn / GWn < 1
C1/GW1 + C2/GW2 + C3/GW3 + …. < 1
C1 … n = measured concentration of the substance in the air
GW1 … n = OEL of the measured substance
34
Odor

Odor = no reliable detection system !!

Some substances have no odor: CO, nitrogen, …!

Substances with the odor level above the OEL !

For some substances at high air concentrations the
odor disappears : Upper odor level H2S: 200 ppm

The effect of “odor habituation” !
35
Risk assessment
36
Risk assessment

The purpose of a risk assessment is to determine the risk
posed by a chemical or a chemical product. The
assessment of the risks of a chemical as such or in a
product, consists of four steps:
1.
2.
3.
4.
hazard identification
dose-response assessment
exposure assessment
risk characterization
37
Hazardous substances - identification
Processes / activities :


CHA/PHA/PHR (Process Hazard Analysis / Review)
= theoretical evaluation of the
exposure
38
Hazardous substances - identification
Raw materials :


chemical & toxicological properties
user information
39
Evaluation of risks
Monitoring workplace:
= evaluation exposure at workplace
• Stationary / personal
• Portable / fixed
• Short term / 8 hours
Bio monitoring:
= effects on individual employee
• blood, urine
• long function
• clinical evaluation
40
Hazardous substances - evaluation

Different measuring principles - gases & vapors:
Long term
Leak detection
Short term
Bio monitoring
Stationary monitoring
41
Hazardous substances - evaluation

Different measuring principles - dust & solids :
Long term
Bio monitoring
Short term
42
Hazardous substances - identification
Installations : control measures
 Engineering controls
– Closed transfer
– Isolators
– Compartments
– Local & overall ventilation
 Administrative controls
– Procedures
– Safe behavior analyses
 Personal protective equipment
43
Engineering control – prevention hierarchy
High integrity transfer
Isolator
technology
Closed Transfer
Direct Laminar Flow
Laminar Flow
Local ventilation
44
Hierarchy of Controls

Elimination

Substitution

Local / General Ventilation

Contained installations

Administrative Controls

Personal Protective Equipment
45
Hazardous substances - control

Elimination : removing asbestos

Substitution : chloroform, benzene, 1,2-DCE

Encapsulation : isolators

Overall & local ventilation

Procedures & instructions (work instructions)

Organizational measures (reduce exposure)

Personal protective equipment
46
BIOLOGICAL HAZARDS
Biological Hazards

'biological agents` shall mean micro-organisms, including
those which have been genetically modified, cell cultures
and human endoparasites, which may be able to provoke
any infection, allergy or toxicity.

Types of biological hazards :
– Viruses (e.g. hepatitis C, yellow fever)
– Fungi or Molds
– Bacteria (e.g. legionella, salmonella )
– Plants
– Insects
– Animals
48
Biological hazards

Indicative list of activities with possible exposure to
biological hazards :
– food production,
– activities where there is contact with animals and/or
products of animal origin,
– health care, including isolation and post mortem units,
– clinical, veterinary and diagnostic laboratories, excluding
diagnostic microbiological laboratories,
– refuse disposal plants,
– sewage purification installations.
49
Biological hazards
Biological agents are classified into risk groups, according to
their level of risk of infection:



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group 1 = unlikely to cause human disease;
group 2 = can cause human disease and might be a hazard to
workers; it is unlikely to spread to the community; there is usually
effective prophylaxis or treatment available;
group 3 = can cause severe human disease and present a serious
hazard to workers; it may present a risk of spreading to the
community, but there is usually effective prophylaxis or treatment
available;
group 4 = causes severe human disease and is a serious hazard to
workers; it may present a high risk of spreading to the community;
there is usually no effective prophylaxis or treatment available.
50
Risk prevention

If possible, a harmful biological agent, is to be replaced
with a biological agent which, under its conditions of use,
is not dangerous or is less dangerous to workers' health,
as the case may be, in the present state of knowledge.

Exposure must be prevented.

Prevention measures and requirements are different with
respect to the classification of the biological hazard (e.g.
Construction of the workplace, registrations of exposures,
notification of the Government, training programs,
collective protection, …)
51
Risk reduction

The risk of exposure must be reduced to protect the H&S of
the workers, in particular by the following measures :
– an as low as possible number of workers exposed;
– work processes and engineering control measures to avoid or
minimize the release of biological agents;
– collective protection measures and/or, in addition, individual
protection measures;
– hygiene measures to prevent or reduce the accidental transfer
or release of a biological agent;
– use of the biohazard sign;
– plans to deal with accidents;
– testing, where technically possible, for the presence, outside
the primary physical confinement;
– means for safe collection, storage and disposal of waste;
– arrangements for the safe handling and transport.
52
Hygiene & individual protection






No eating or drinking in working areas where there is a risk of
contamination by biological agents;
Use of appropriate protective clothing or other special clothing;
Appropriate and adequate washing and toilet facilities, which
may include eye washes and/or skin antiseptics;
Protective equipment properly stored in a well-defined place,
checked and cleaned, and replaced if needed;
Working clothes and protective equipment, must be removed
on leaving the work-area and kept separately from other
clothing.
Working clothing and protective equipment must be
decontaminated and cleaned or, if necessary, destroyed.
53
PHYSICAL HAZARDS
NOISE
Noise

Noise is defined as unwanted sound
or noise pollution.

Noise is measured in decibels (dB).
An 'A-weighting' sometimes written
as 'dB(A)', is used to measure
average noise levels, and a 'Cweighting' or 'dB(C)', to measure
peak, impact or explosive noises.
Remember every 3 dB doubles the
noise, so what might seem like small
differences in the numbers can be
quite significant.


56
Noise

To evaluate the noise hazards the physical parameter
used as risk predictors are defined as follows: daily noise
exposure level (LEX,8h) (dB(A) re. 20 μPa) being the
time-weighted average of the noise exposure levels for a
nominal 8-hour working day.
57
Effects of noise

Hearing impairment and hearing disorders

Noise and pregnant workers

Work related stress

Influence on work tasks

Disturbance of speech communication

Noise as a cause of accidents

Other health effects
58
Hearing impairment and hearing disorders
= Most important effect of occupational noise

Excessive exposures to noise are probably the most common
cause of hearing loss due to damage of the inner ear. In general,
prolonged exposure to sound levels > 85 dB(A) is potentially
hazardous although the important factor is the total amount of
exposure given by the level and length of exposure time.

Risk of instant, irreversible damage begins at +/- 130–140 dB(C)
peak level. (explosions, firearm reports, or electric arcs).
59
Noise & health surveillance
Health surveillance for hearing damage usually means:
 regular hearing checks in controlled conditions;
 telling employees about the results of their hearing
checks;
 keeping health records;
 ensuring employees are examined by a doctor where
hearing damage is identified.
60
Risk prevention
Actions to prevent risks are :

assessment of the risks;

prevention of exposure, including the use of personal
hearing protection;

limitation of exposure in accordance with exposure
and action levels;

health surveillance;

information, consultation, and training to, with, and of
workers.
61
Risk assessment …
Assessment of risks arising from exposure to
noise should consider :





the level, type, and duration of exposure, including any
exposure to impulse noise;
the exposure limit values and action values;
effects of noise on the H&S of workers in ‘risk groups’;
effects on workers' H&S resulting from interactions
between noise and work-related ototoxic substances, and
between noise and vibrations;
any indirect effects on workers’ H&S resulting from
interactions between noise and warning signals or other
sounds;
62
… Risk assessment

information on noise emission provided by manufacturers
of work equipment in line with the relevant directives;

the existence of alternative work equipment designed to
reduce the noise emission;

the extension of exposure to noise beyond normal
working hours under the employer’s responsibility;

information obtained from health surveillance;

the availability of hearing protectors with adequate
attenuation characteristics.
63
Risk reduction in practice …
The reduction in risks from exposure to noise should take
into account:

other working methods that need less exposure to noise;

the choice of suitable work equipment, taking account of
the work to be done, emitting the least possible noise;

the design and layout of workplaces and work stations;

adequate information and training to instruct workers to
use work equipment correctly in order to reduce their
exposure to noise to a minimum;
64
… Risk reduction in practice

noise reduction by technical means:
– reducing airborne noise by means such as shields,
enclosures, and sound-absorbent coverings;
– reducing structure-borne noise by means such as damping
or isolation;

appropriate maintenance programs for work equipment,
the workplace and workplace systems;

organization of work to reduce noise, by:
– limitation of the duration and intensity of the exposure;
– appropriate work schedules with adequate rest periods.
65
Organizational & administrative noise control
Reduction of noise risks by organizational noise-control
measures should consider:
 noise emissions as an evaluation factor in a procurement
policy;
 working methods which generate less noise;
 organization of work to reduce noise.
The organization of work could limit the duration and
intensity of exposure by:
 keeping the number of exposed workers to a minimum;
 task rotation;
 scheduling noisy activities for when fewer workers are
exposed;
 appropriate work schedules with adequate rest periods.
66
Hearing protection ?

If the risks arising from exposure to noise cannot be
prevented by other means;

When technical noise control is ineffective, infeasible or
prohibitively expensive;

Individual hearing protectors should be selected to
eliminate the risk to hearing, or to reduce the risk to a
minimum, or at least to make sure the exposure limit
values are not exceeded;

Ensure the wearing of hearing protectors;

Check the effectiveness of the measures taken.
67
Hearing protection
Some types of hearing protection devices :

Earplugs : Vinyl, silicone, spun fiberglass, cotton/wax
combinations, and closed-cell foam products that are inserted
or semi-inserted in the ear canal to form a noise blocking seal.
Comparatively, the attenuation is better below 500 Hz and
above 2.000 Hz.

Earmuffs : Ear cups, usually of rigid plastic material with an
absorptive liner, that completely enclose the outer ear and seal
around it with foam- or fluid-filled cushions. Comparatively, the
attenuation is better at intermediate frequencies.

Earmuffs With incorporated active noise cancellation : a
new technology that especially for the lower frequency range
offers an active noise-level-dependent attenuation, as well as a
passive protection.
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Information and training
Workers exposed to noise should receive information and
training on the risks of that exposure, in particular:

the nature of such risks;

the measures taken in order to eliminate or minimize the risks;

the exposure limit and exposure action levels;

the results of the assessment and measurement of the noise
and an explanation of their significance and potential risks;

the characteristics and properties of the hearing protectors;

the correct use of hearing protectors;

why and how to detect and report signs of hearing damage;

the circumstances in which health surveillance is applicable;

safe working practices to minimize exposure to noise.
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VIBRATIONS
Vibrations

Vibration is mechanical oscillation about a reference
position.

Vibration is an everyday phenomenon, we meet it in our
homes, during transport and at work.

Vibration is often a destructive and annoying side effect
of a useful process, but is sometimes generated
intentionally to perform a task.

For occupational health the exposures to hand-arm
vibrations and whole-body vibrations are concerns.
71
Hand-arm vibrations

hand-arm vibration : the mechanical vibration that, when
transmitted to the human hand-arm system, entails risks
to the health and safety of workers, in particular vascular,
bone or joint, neurological or muscular disorders.

The assessment of the exposure is based on the
calculation of the daily exposure value normalized to an
8-hour reference period, expressed as the square root of
the sum of the squares (rms) (total value) of the
frequency-weighted acceleration values, determined on
the orthogonal axes ahwx, ahwy, ahwz.
72
Whole-body vibrations

Whole-body vibration : the mechanical vibration that,
when transmitted to the whole body, entails risks to the
health and safety of workers, in particular lower-back
morbidity and trauma of the spine

The assessment of the exposure to vibration is based on
the calculation of daily exposure expressed as equivalent
continuous acceleration over an 8-hour period, calculated
as the highest (rms) value, or the highest vibration dose
value (VDV) of the frequency-weighted accelerations,
determined on three orthogonal axes (1,4awx, 1,4awy,
awz).
73
OEL & action levels
Vibrations
Hand-arm
Whole body
OEL
5m/s²
1,15m/s²
Action levels
2,5m/s²
0,5m/s²
74
Reduction program for exposure to vibrations
technical and/or organizational measures :









other working methods that require less exposure;
choice of appropriate work equipment of appropriate
ergonomic design producing the least possible vibration;
the provision of auxiliary equipment that reduces the risk
of injuries caused by vibration;
appropriate maintenance programs for work equipment,
the workplace and workplace systems;
the design and layout of workplaces and work stations;
adequate information and training to instruct workers;
limitation of the duration and intensity of the exposure;
appropriate work schedules with adequate rest periods;
provision of clothing to protect from cold and damp.
75
RADIATION
Radiation

Ionizing radiation (high energy) : AlphaBeta-Gamma

Non-ionizing radiation (low energy) : UVlight, visible light, infrared, radio waves,
microwaves
77
Radiation; ionizing & non-ionizing
78
Ionizing radiation (high energy)




Ionizing radiation is transmitted by radioactive materials
and certain equipment
It can permeate through many materials
There are 3 types of ionizing radiation; alpha, beta &
gamma radiation
Ionizing radiation can have various effects on health;
– Radiation sickness occurs after exposure to a very high
dose of radiation. It normally leads to death.
– Exposure to a moderate dose can lead to radiation tumors.
– Other effects are changes in the hereditary material (DNA)
like infertility, malformation of the unborn child and cancer.
79
Non-ionizing radiation (low energy)


Is electromagnetic radiation with a lower frequency.
There are different types;
–
–
–
–
–


UV : eg. Welding arcs, lasers, …
Visible light : lamps, TL-tubes, welding arcs, lasers, …
Infrared : heat lamps, electrical heaters, welding process, …
Radio waves : heating, signal transfer, plastic sealing, …
Microwaves : electromagnetic waves
High exposure levels can heat up the body tissue.
Prolonged exposure to low levels could cause health
damage, depending on the wavelength, the energy content
and the depth of the penetration, like inflammations of the
eye, skin burns, tumors or melanomas and reduced fertility.
80
Control measures for radiation

No eating, drinking or smoking at the workplace.

Implement consequent personal hygiene.

Leave the packaging of radioactive material intact.

Do not dismantle radioactive sources.

Use specific personal protective equipment.

Place warning signs.

Cordon off the areas around a radioactive source.
81