2-15. SAMPLING TECHNIQUES
a. The collection and analysis of representative samples of the air in the work
place is an important means of determining the nature and extent of occupational
hazards or exposures associated with an operation or process. In addition, the
effectiveness, or the inadequacy, or exiting control measures may be demonstrated by
appropriate sampling. In this regard, the preventive medicine specialist will frequently
be called upon to assist in the collection of samples of potentially contaminated air in a
variety of work places on Army installations. Very often this sampling will be conducted
for the purpose of determining compliance with Department of the Army and OSHA
environmental standards. There are a number of important factors that must be
considered during the collection of samples if reliable results are to be obtained.
Disregarding any of these factors can seriously limit the accuracy of the data collected
and can lead to invalid conclusions.
b. Before the sampling technique or method can be selected, some basic
questions must be answered:
Where should sampling be done?
Whom (which workers) should be sampled?
How long should each sampling period be?
How many samples will be necessary?
When should sampling take place?
c. The sampling location will be dictated by the kind of information needed or
the type of evaluation desired. It may be one, or a combination, of the following.
(1) General room (area or background) air sample. The general room air
sample provides an indication of the total concentration of a contaminant in the overall
work area. Such sampling gives qualitative data on what contaminants are present in
the work area and to some extent indicates if control measures are effective.
(2) Breathing zone/personal sample. The breathing zone personal sample
more definitely determines the worker's exposure to a contaminant. From breathing
zone samples, a daily time-weighed average can be determined. Frequently breathing
zone samples are used in conjunction with biological samples such as urine and blood
to assess the total effect the exposure has on the worker.
(3) Operation/process area sample. This third type of sampling is done at
the operation or process area itself and will provide both qualitative and quantitative
information about the influence of the operation or process on those exposed to it and
the need for local control of the contaminant. It also allows the identification of the step