Parameters that bias the measurement of airborne concentration within a respirator
This paper describes the theoretical basis upon which a test system has been set up to evaluate the sampling error associated with in-facepiece sampling on half-mask respirators. The in-facepiece sampling technique evaluated in this study is the one currently used in the US to conduct quantitative facepiece fit testing. An experimental design was developed to study the sampling bias associated with in-facepiece sampling when selected parameters of the man/respirator system were varied. The results indicated that significant errors can be made in estimating concentration within a respirator when the current in-facepiece sampling technique is employed. Sampling bias was determined when in-facepiece samples were collected only during the inhalation phase of the respiratory cycles. They were found to range from greater than -99% to greater than +98%. The mean sampling bias was -17 +/- 38%. When measured in-facepiece concentrations were used to calculate a fit factor the resulting range was 44 to 4728 even though the actual fit factory was only 87. Based upon the data presented, it was hypothesized that faceseal leakage was streamlining within the respirator cavity. As a result, quantitative facepiece fit data on half-mask respirators may be biased by the large measurement error.
- Research Organization:
- National Institute for Occupational Safety and Health, Morgantown, WV
- OSTI ID:
- 5813301
- Journal Information:
- Am. Ind. Hyg. Assoc. J.; (United States), Journal Name: Am. Ind. Hyg. Assoc. J.; (United States) Journal Issue: 2 Vol. 47:2; ISSN AIHAA
- Country of Publication:
- United States
- Language:
- English
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