Data Validation and Interpretation

When an employee is sampled and the results analyzed, the measured exposure will rarely be the same as the true exposure. This variation is due to sampling and analytical errors (SAE's). The total error depends on the combined effects of the contributing errors inherent in sampling, analysis, and pump flow.

• OSHA Technical Manual (OTM). OSHA Directive TED 01-00-015 [TED 1-0.15A], (January 20, 1999). The following section, which were updated February 11, 2014, describes the process of determining errors with a given degree of confidence by using statistical methods:
  • Personal Sampling for Air Contaminants

Consider the following questions when analyzing results:

• Do the results make sense?
• Based on knowledge of the sampling site, are the laboratory results consistent with what you expect?
• And are they consistent between samples?
• Are the results consistent with previous sampling results?
• If an error in analytical procedures or results is suspected, contact the laboratory quality assurance section for assistance and resolution.
• Were the samples collected using the correct sampling method and were the method specifications followed?
• Was the correct sampling media used?
• Were the sample flow rates and total volumes within specifications?
• Were samples properly preserved and shipped?
• Was there a possibility of contamination? Were blanks submitted for analysis?
• Were there any unusual circumstances surrounding the sample collection which may influence the validity?