Clayton Group Services, Inc.

Industrial Hygiene: Quality Assurance In Air Sampling and Analysis

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Courtesy of Clayton Group Services, Inc.

Industrial hygiene is the recognition, evaluation, and control of chemical, physical, biological, and ergonomic stresses in the workplace. Of the stresses listed, chemical stresses in the form of air contaminants are the most common. Air contaminants, their PELs and TLVs, and how to sample for them, is Industrial Hygiene 101 for most industrial hygienists. However, as simple as sampling and analysis may seem at first glance, every industrial hygienist or industrial hygiene chemist has at one time or another ended up with a sampling situation without the right media, a sample that couldn't be analyzed, a lab result that was uninterpretable, or data that didn't answer the question asked.

What could have been done differently to change these situations? It is likely that adherence to a well-defined quality assurance program would have helped.

What is Quality Assurance?

Quality assurance is not just control charts and data. Quality assurance is the sum of all those activities in which the industrial hygiene department or laboratory is engaged to ensure that information generated is correct. Quality assurance is a system to reduce measurement errors to agreed upon limits and to provide a means of ensuring that the measurements generated have a high probability of being of acceptable quality.

Two concepts are involved in quality assurance. Quality control is the mechanism established to control errors, while quality assessment is the mechanism to verify that the system is operating within acceptable limits.

Why is Quality Assurance Important in Air Sampling and Analysis?

To quote George Clayton, a well-known pioneer in industrial hygiene, as he lectured some industrial hygienists early in their careers:

'I needn't tell you the probability of error in a single sampling result
considering the number of steps in sampling and analysis.'

The steps in sampling and analysis, shown in Table 1, confirm Mr. Clayton's statement. They are extensive.

The potential for error is present in all manual operations: sampling technique, pump calibrations, sample storage, shipment, aliquoting, dilution, concentration, separation, analytical calibration, and instrument operation. In addition, gross errors resulting from loss of sample identification, error in calculation, error in sampling strategy, or use of inappropriate methods are possible. Because of the many sources of error in sampling and analysis, a system to reduce errors to acceptable levels is essential so true estimates of probable air contaminant levels can be obtained.

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