The document discusses the three main elements of industrial hygiene: recognition, evaluation, and control of occupational health hazards. It describes the process of recognizing hazards through workplace inspections and data collection, evaluating exposures through measurements and comparisons to standards, and controlling hazards through engineering controls, substitutions, administrative controls, work practice controls, and personal protective equipment if other options are not possible. Recognition of hazards is the first step to properly evaluating and controlling them to protect worker health.

1. Industrial hygiene
Dr. N. Yuvaraj
Assistant Professor
Achariya Arts and Science College
Villianur , Puducherry

2. The 3 definite elements in industrial hygiene are the
1. Recognition,
2. Evaluation and
3. Control of occupational health hazards.
The recognition of health hazards has primacy, since it must take
place before proper evaluation or (if needed) control can take
place.
Upon recognition of a health hazard, the industrial hygienist
should be able to identify measures necessary for proper
evaluation.

3. Upon completion of the evaluation, the industrial hygienist then
is in a position – in consultation with other members of the
occupational health safety team – to recommend controls
needed to reduce exposures to tolerable limits.
Recognition of health hazards in the workplace
is the first step in the process leading to evaluation and control
and entails the identification of materials and processes that
have the potential for causing harm to workers.

4. Sources of information about health hazards include
Clinical data about health problems in exposed populations;
Information in scientific journals and
Reports of government agencies;
Direct reports from workers,
Union representatives,
Supervisors, or employers.

5. Inspection of the workplace is the best source of directly
relevant data about health hazards.
There is no substitute for observation of work practices, use of
chemical and physical agents, and apparent effectiveness of
control measures.
The physician should be able to recognize major and obvious
health hazards and distinguish those that require formal
evaluation by the industrial hygienist.

6. The “walk through survey” in the company of the occupational
health physician is the first and most important technique
for recognition of occupational health hazards.
The survey should begin with a proper introduction to plant
management and discussion of the purpose of the survey and
inquiry about any relevant recent complains.

7. Following the process flow through the plant is productive.
The survey might thus begin at the loading dock, where
materials entering the plant can be examined.
Warning labels, descriptive language about the chemical
composition of materials, and the packing of the incoming
materials should be noted.

8. Questions should then be asked regarding the handling of
unknown materials or materials about which insufficient
information is available.
The incoming materials should then be followed into the
process flow stream, and each of the process of interest in
the plant should be observed in action.
Of interest throughout the survey will be the methods used
for material handling, particularly at the places where they
are transferred from manufacturers’ containers into vessels
for use within the plant.

9. Observations to be made.
At each point in the process, the industrial hygienist should
observe handling procedures as well as any protective measures
that are employed.
Use of respiratory protection and protective clothing should be
recorded, as well as other common sense observations such as
the apparent effectiveness of engineering controls – as
indicated by absence of characteristic odors, visible dust
accumulations, and loud noise.

10. The survey should continue through to the final product produced
by the plant and its packing.
The industrial hygienist should also follow the pathway of any
waste materials and determine their disposal sites.
The number of employees at each step should be noted, as well as
any relevant data on gender, ethnicity, or age that might affect
employees’ sensitivity to chemicals in the workplace.
It is also important to look for obvious stigmas such as drying of
skin, as might expected where exposure to solvents occurs.

11. Important part of the industrial hygienist’s role in recognition
of health hazards in the workplace will be data review.
Such data may include reports from physicians on clinical
findings that may be related to exposures in the workplace as
well as a review of company records on materials coming into the
workplace that may present significant hazards.

12. A common-sense duty of the employer is to inform workers of
the nature and hazards of materials to which they may be
exposed.
In some cases, the industrial hygienist must assess the potential
for harm of chemicals for which no reliable human toxicological
data are available
This need arises most often in research and development
settings but also wherever chemical intermediates are produced.

13. An important consideration is that the worker must be protected
at all cost.
If uncertainty exists, it should be resolved in favor of highest
standard of concern.
Upon competition of the walk-through survey, the industrial
hygienist will ordinary have a closing conference with the plant
management, at which time obvious concerns can be discussed
and follow-up measures agreed upon.

14. 2).Evaluation of health hazards
Evaluation of health hazards within the plant will include
measurements of exposures, comparison of those exposures to
existing standards, and recommendations of controls, if
needed.
Exposure measurements.
They are intended to be determinations of doses delivered to
the individual.

15. The mere existence of chemicals in the workplace – or even in the
workplace atmosphere – does not necessary imply that the
chemicals are being delivered to a sensitive organ system.
The effective dose will depend upon such things as particle sizes
of dusts in the air, the use of protective devices (respirators,
protective clothing), and the existence of other contaminants in
the workplace.
The task of determining the dose delivered to the worker may be
complicated by the existence of multiple pathways of absorption
and metabolism.

16. Such contaminants as lead are absorbed readily both through
inhalation and ingestion, and both routes of intake must be
considered in evaluation of the potential for harm.
Similarly, many solvents are readily absorbed through the skin,
and mere determination of airborne levels is not sufficient to
determine the complete range of potential exposures.

17. Inhalation of airborne contaminants is the major route of
entry for systemic intoxicants.
Thus, evaluation and control of airborne contaminants is an
important part of any occupational health program.
Sampling and analysis of airborne contaminants is the
definite function of the industrial hygienist.
The methods for sampling and analysis of airborne
contaminants have been already discussed.

18. Evaluation of physical agents requires specialized equipment
that is often not routinely available (except for sound level
meters).
Evaluation of ionizing or non-ionizing radiation requires
specialized training.

19. 3).Control of health hazards
Upon completion of evaluation, the industrial hygienist should
recommend appropriate controls, if needed.
Recommendations should take into account not only the
conditions found during the survey but also those that may be
expected to prevail in the future.
Controls should be adequate to prevent unnecessary exposure
during accidents and emergencies as well as during normal
conditions.

20. Engineering controls
Engineering controls to toxic exposures consist mainly of:
- enclosure – building structures around the sources of
emissions
- isolation – placing hazardous process components in areas
with limited human contact and
- VENTILATION

21. Local exhaust ventilation confirms to the principle that control
should be implemented as near to the source as practically
possible.
Thus, application of a local exhaust inlet on a specific tool (such
as grinder) would be more desirable than performing the grinding
operation in a ventilated hood, which in turn would be more
desirable than installing general ventilation in the room where
the grinding is performed.

22. In a situation where a very toxic substance is being manipulated
in such a way that the exposure is possible, all 3 ventilation
systems might be reasonable to use.
Thus, the operator would be protected by the ventilation of the
specific tool, nearby workers (as well as the operator) would be
protected by the hood and the reminder of the building would be
protected by the general ventilation system.

23. Design of ventilation systems for contamination control should
ordinarily not to be left to engineers without specific
background or experience.
Similarly, an industrial hygienist without engineering training
and experience in the process to be controlled may produce an
unsatisfactory design.

24. Substitution
All possibilities for substitution of a nontoxic for a toxic
material or agent should be explored.
If a toxic material can be dispersed with a less harmful, that
should be done.
Substitution can be done, of course, if a useful substitute is
available – one that is suitable for existing processes or for
which the process can be relatively easily adapted.

25. Controls on human behavior
these can be subdivided into the general categories of
administrative c ontrols and work practice controls.
Administrative controls – includes such things as
establishment of prohibited areas, areas where smoking and
eating are either prohibited or allowed, and safe pathways
through the work environment.

26. Administrative controls will also include work scheduling in such
a way that dangerous operations are carried out when fewest
workers are present.
Less desirable is the practice of scheduling individual workers
to perform tasks for short periods, where excessive exposures
would be incurred.

27. This practice was at one time common in nuclear power
industry, where temporary employees (“jumpers”) were
employed and paid by the day, although their actual work
period may have been as short as 15 minutes.
Such practices, where exposure to carcinogenic or
genotoxic agent is spread across a larger population
group although individual exposures are lower, is entirely
unacceptable.

28. Work practices control
– implies control over the behavior of individual workers on the
job.
Such details as handling of contaminated tools are included.
Education (on the hazards to be avoided) and training (on the
desired practices) are required.
Controls on work practices are particularly important where
engineering controls are either not adequate or not possible and
where there is significant potential for generation of airborne
contaminants outside of controlled places.

29. Personal protection
Personal protective equipment use, though often essential, is
less desirable than other approaches because of the
difficulty in ensuring that it is both used and effective.
Examples on construction sites are “hard hats” and “safety
shoes”.

30. In laboratory environments, the use of protective eyewear is
common, as is the use of protective garments, such as
laboratory coats.
However, there are significant complexities in both design
and function of the protective devices used to reduce
exposures.