1. OVERVIEW OF INDUSTRIAL
HYGIENE
PRINCIPLES OF
EVALUATING WORKER
EXPOSURE

2. DEFINITION
Industrial Hygiene (IH) is that science
devoted to the anticipation, recognition,
measurement, evaluation, and control of
adverse occupational stresses or agents
which could cause sickness and impaired
health among workers and the
community. The basic goal of IH (i.e.
occupational hygiene) is to promote a
safe and healthful work environment.

3. OCCUPATIONAL HYGIENE
The science and art of anticipating,
recognizing, evaluating, and controlling
health hazards in the workplace. The
purpose of this introduction is to provide an
understanding of the general principles of
evaluating worker exposures in the
industrial environment.

4. IH FOCUS
1. Hazardous agents in workplace
2. Health effects associated with
excessive exposures
3. Occupational Exposure Limits (OELs)
for each agent
4. Workforce organization and staffing
5. Significant sources of exposure; tasks
and work procedures involved
6. Control measures

5. IH ELEMENTS
 Anticipation
 Recognition
 Evaluation
 Control

6. ANTICIPATION
Expectation of potential health hazards is
generally more difficult for the entry-level,
inexperienced occupational hygienist since skills in
anticipation generally increase with experience.
Ability to recognize potential health hazards as
well as knowledge of scientific developments, new
technologies, and regulatory requirements, etc.

7. RECOGNITION
Requires knowledge and understanding of
workplace environmental stresses and effects on
health of the worker related to processes and
control measures; inventory of chemical,
biological, and physical hazards; potential
chemical hazards are determined by toxicity and
also conditions of use. Involves collection of
available information along with the application of
IH principles.

8. RECOGNITION
Detailed information to be obtained
regarding types of hazardous materials
used, type of job operation, worker
exposures and patterns, levels of air
contaminants, exposure duration, control
measures, etc. Consult product information.
Develop workplace characterization which
results in defining “exposure groups” for
same tasks/similar manner.

9. TOXICITY VS. HAZARD
 Toxicity is the capacity of a material to
produce injury or harm to living tissue
when the chemical has reached a
sufficient concentration at a certain site
in the human body.
 Hazard is the probability that this
concentration will occur within the body;
affected by many factor/elements
generally related to conditions of use.

10. EVALUATION
Involves observation as well as monitoring
and use of analytical methods required to
detect the extent of exposure; decision-
making process resulting in an opinion on the
degree of health hazards and/or stressors
that exist; determine significance (e.g.
subjective/objective judgment); extent of
potential health hazards based on
comparisons of environmental measurements
with current governmental regulations and
recommended technical guidelines.

11. EFFECTIVE EVALUATION
 Utilize a multi-disciplinary approach including
knowledge-based technical information.
Contributions include: occupational hygiene,
chemistry, engineering, health physics, medicine,
epidemiology, toxicology, and nursing disciplines
as well as management and manufacturing
expertise.
 Integrate knowledge and develop control
strategies for potential risk limitation.
 Consider team-based efforts of personnel.

12. EVALUATION
 Exposure assessment: initial qualitative method
for prioritization; then, semi-quantitative (i.e.
mathematical modeling) or quantitative (i.e.
monitoring) methodologies.
 Air monitoring can be involved for quantitative
assessment; breathing zone exposures preferred.
 On-going process: feedback from multiple
sources of information; refine exposure estimates;
evaluate control effectiveness; priorities change!

13. EXPOSURE ASSESSMENT
 Control exposures
 Compliance determinations
 Program management (i.e. respiratory;
hearing/noise; medical surveillance, etc.)
 Epidemiologic studies
 Health complaint investigations
 Risk assessment
 Proposed change evaluations to process

14. CONTROL
Involves the reduction of environmental
stresses to levels that the worker can
tolerate without impairment of health or
productivity; various general control
methods employed for accomplishments in
an efficient and effective manner.

15. CONTROL
Defined as the adjustment or regulation of
an operation to meet a standard or
guideline, the reduction or prevention of
contaminant release, and the ability to
contain a stressor/hazard.

16. CONTROL METHODS
 Engineering – remove the hazard; should
be primarily considered.
 Administrative – reduce exposures through
scheduling/job rotation; housekeeping;
employee training; not generally favored.
 Personal Protective Equipment (PPE) – use
should be secondary to design and
implementation of engineering controls.

17. ENGINEERING CONTROLS
• Substitution
• Change in process
• Source modification
• Isolation
• Enclosure
• Wet methods
• Ventilation

18. ADMINISTRATIVE CONTROLS
EXAMPLES:
- Arranging work schedules and the
related frequence/duration to limit
employee exposures to health hazards.
- Transferring employees at PELs to an
environment where additional exposure
is not anticipated.
- Housekeeping; preventive maintenance.

19. ADMINISTRATIVE CONTROLS
Administrative controls must be designed
only by knowledgeable health and safety
professionals, and used cautiously.
Not as satisfactory as engineering controls
and have been criticized as a means of
spreading exposures instead of reducing or
eliminating personal exposures.

20. PPE
PPE may be used to protect the worker
when it is not feasible to render the working
environment completely safe. Examples:
eye/foot/head protection, gloves,
respirators.
Considered a secondary control method to
engineering and administrative controls and
should be used as a last resort.

21. EFFECTIVE IH PROGRAM
Applies knowledge to the anticipation and
recognition of health hazards arising out of
work operations and processes, evaluation
and measurement of the magnitude of the
hazard based on past experience and
study, and control of the occupational
hazards.

22. POTENTIAL HAZARDS
 Chemical
 Physical
 Biological
 Ergonomic

23. CHEMICAL HAZARDS
 Hydrocarbons
 Solvents
 Oil Mist
 Dust (Total and Respirable)
 Crystalline Silica
 Formaldehyde
 Carbon Monoxide
 Airborne Fibers

24. PHYSICAL HAZARDS
 Noise
 Radiation
- Ionizing
- Non-ionizing
 Lighting
 Heat/Cold Stress
 Pressure Extremes

25. BIOLOGICAL HAZARDS
 Bioaerosols
 Surface/Bulk Contamination
 Tuberculosis
 Bloodborne Pathogens
 Indoor Air Quality Issues

26. ERGONOMIC HAZARDS
 Musculoskeletal Disorders
 Cumulative Trauma Disorders
 Carpal Tunnel Syndrome
 Material Handling/Lifting
 Workplace Design Considerations

27. OTHER HAZARDS
 Confined Spaces
 Waste Management
 Lab Health and Safety
 Emergency Planning
 Etc. . .

28. EXPOSURE ASSESSMENT
Determination or estimation of the magnitude,
frequency, duration, and route of exposure.
 Determine purpose and scope of survey
 Become familiar with process operations
 Perform the preliminary, qualitative survey
 Conduct workplace monitoring as a
quantitative evaluation
 Interpret the sampling results.

29. TYPES OF EVALUATIONS
 Comprehensive exposure assessment to
identify and quantify health hazards
 Assess compliance with regulatory
standards and/or technical guidelines
 Review exposures based on complaints +
 Exposure assessment for medical and
epidemiological studies +
 Determine effectiveness of engineering and/
or administrative controls +

30. COMPREHENSIVE EXPOSURE
ASSESSMENT
Primary objective is to determine the
acceptability of exposures to health hazards
for all workers in designated work areas or
for specific operations.
Based on identification and
quantification/estimation of exposures to
workplace stressors, then use of walk-through
survey procedures for hazard identification,
and subsequently, evaluation techniques to
estimate employee exposure levels are
employed.

31. COMPLIANCE SURVEY
Exposure to stressors are quantified and
evaluated by comparison to published health
standards, Permissible Exposure Limits
(PELs) or technical recommended guidelines
such as American Conference of
Governmental Industrial Hygienists (ACGIH)
Threshold Limit Values (TLVs).
Determine compliance vs. non-compliance.

32. PROCESS OPERATIONS
 Physical facility layout
 Process description and steps
 Inventory of process stressors/hazards
 Worker job classifications
 Worker health status
 Control measures in place
 Results from past evaluations
 Other associated process hazards

33. PROCESS METHODOLOGY
Information obtained through interviews,
personal/visual observations, technical
process information, and record reviews.
A walk-through survey is an important
methodology to understand, verify, and/or
modify documentation; look for potential
sources of health hazards and chemical air
contaminants and physical agents.

34. INVENTORY
 Hazard/Stressor listing for identification
 Chemical and physical agents
 Toxicological information; reference sources
 Occupational Exposure Limits (OELs)
e.g. OSHA PELs, ACGIH TLVs,
NIOSH RELs, AIHA WEELs,
ANSI, NIOSH Pocket Guide

35. JOB CLASSIFICATIONS/
WORK HEALTH STATUS
Formal job descriptions, and personnel
interviews with employees/supervisors.
Worker health status – medical surveillance
for health hazard recognition and workplace
logs of incidents/injuries/illnesses for
assistance with stressor identification.

36. PAST EVALUATIONS/
IDENTIFY POTENTIAL HAZARDS
Review of past occupational hygiene or
related evaluations. Determine: time
elapsed; process changes, identification of
significant problems, and/or other indicators.
Personnel interviews and site review. Get
workers involved in the familiarization step
of a survey to assist with acceptance.

37. PRELIMINARY ASSESSMENT -
QUALITATIVE
Familiarity with process/operation to
qualitatively evaluate magnitude of
stressors without benefit of instrumentation.
Visual observations; use of senses (i.e.
smell); inspection of control measures
implemented and effectiveness; and, PPE.

38. WORKPLACE MONITORING -
QUANTITATIVE EVALUATION
Document exposure levels either by
measurement or use of semi-quantitative
methods. Strategy developed depends on
the reason for evaluation. Purpose is
FIRST!
Sampling objectives: EITHER engineering
testing, surveillance, or control; OR
compliance, health research, or
epidemiological purposes.

39. STRESSOR IDENTIFICATION/
CONCENTRATION ESTIMATION
Hazard information by familiarization and
then prioritization (probability/consequence
of overexposure) based on significance for
monitoring.
Probable range of contaminant
concentrations to assist with sampling
strategy development and facilitate
selection of monitoring methods and/or
specific equipment for assessment.

40. SAMPLING AND ANALYTICAL
METHOD SELECTION
Use of accurate, sensitive, specific, and
reproducible analytical methods and proper
calibrated sampling equipment. Knowledge
of interferences and detection limits.
Principles – validated methods (OSHA,
NIOSH).
Specificity, selectivity, and other
considerations for direct-reading instruments.
Limitations - combine workplace
observations with measurements for result
interpretation.

41. EQUIPMENT DECISIONS
 Type of analysis or information required
 Efficiency of the instrument
 Reliability of the instrument under various
field use conditions
 Exposure assessment for medical and
epidemiological studies
 Portability and ease of instrument use
 Personal choice of IH based on past
experience and other factors

42. EQUIPMENT SELECTION
 Calibration – necessary to insure data
representative of field exposures; results
based on accuracy of instruments (i.e.
direct-reading) and/or sampling and
analytical methods; pre- and post-calibration
to determine air sample volume;
temperature/pressure adjustments
 IH use of proper PPE during field
assessments

43. SAMPLING STRATEGY
Overall plan or framework for sampling that
may include the type and number of
samples to be collected; the methods to be
used, and their accuracy, and the objectives
for monitoring.
Decision made with confidence and
minimum cost and effort.
Complicated by numerous variables.

44. SAMPLNG STRATEGY
 WHAT and WHY?
 Where to sample?
 When to sample?
 How long to sample?
 Whom to sample?
 How many samples to collect?
 How should the samples be obtained?

45. WHERE???
 Personal or area
 Breathing zone
 Location(s) are dictated by Need
 Source of contaminants by Area

46. WHEN???
 Determined by information required
 Type of operation assessed
 Multiple shifts
 Geographic/climatologic conditions

47. HOW LONG???
 Minimum time is usually determined by the
time interval necessary to obtain a sufficient
amount of the contaminant on the sample
media for laboratory analysis.
 Sensitivity of analytical procedure
 Dependent on contamination concentration
 Full work shift for compliance
 Work tasks; partial periods; multiple
samples to measure entire work shift

48. WHOM???
 Depends on purpose of monitoring.
 For compliance, then sample maximum risk
employees with highest exposures.
 Random sample of employee by exposure
group for a comprehensive assessment

49. HOW MANY???
 Dependent on the purpose of workplace
monitoring.
 For comprehensive assessment, a minimum
of six samples for each exposure group may
be needed for a decision of acceptability.
 With time and budget constraints, semi-
quantitative methods may be used. No set
rule!
 Use personal experience to collect optimal
sample number given budgetary
constraints.

50. HOW???
 Instrument choice depends on:
- Portability and ease of use
- Efficiency and analytical method
- Reliability under various conditions of
field use
- Type of analysis or information required
 The choice of instrumentation and testing
and analytical procedures is ultimately
dependent on the capabilities of the
analytical laboratory.

51. SAMPLE COLLECTION
 Follow strategy so as not to bias results or
compromise the integrity of the conclusions.
 Adjustments or modifications as needed
 Phased sampling strategy as an option
 Understand procedures; equipment/supplies
 Understand impact on the work environment
 Recordkeeping – extensive notes and INFO

52. SAMPLING AND ANALYTICAL
PROCEDURES
Selection of measurement method depends
on sampling strategy requirements and
purpose of workplace monitoring based on:
– duration of sampling [TWA vs. STEL],
– sensitivity of the method/detection limit,
– freedom from interferences/result bias,
– time to reporting of results,
– accuracy.

53. INTERPRETATION OF
SAMPLING RESULTS
 Concentrations
 Calculations based on time periods
 Test statistics
 Professional judgment – acute/chronic
 Information for data interpretation
- Precise nature of material/agent
- Intensity/magnitude of exposure
- Reliable knowledge of
frequency/duration

54. COMPARISONS
 TWAs vs. STELS
 Best sampling strategy for full shift
integrated personal sampling; short-term
tasks add more variability [peak/ceiling -
instantaneous]; general area samples are
not specifically recommended.
 OELs – direct result comparison with OSHA
PELs, ACGIH TLVs, NIOSH RELs, AIHA
WEELs, etc.