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Parameters that bias the measurement of airborne concentration within a respirator.
Myers WR; Allender J; Plummer R; Stobbe T
Am Ind Hyg Assoc J 1986 Feb; 47(2):106-114
A test system to evaluate sampling error associated with in facepiece sampling of half mask respirators was described. Sample mixing within the facepiece cavity was assessed in a screening experiment utilizing a fixed effect 3k factorial design and an in facepiece sampling technique used to conduct quantitative facepiece fit testing. The factors for analysis included sampling probe location, sampling probe depth, leak site on the faceseal perimeter, breathing distribution patterns, and measurement sample rate. The equations used to predict the actual concentration of sample within the facepiece cavity were described in detail. The sample tested was acetone (67641), and the predicted and measured concentrations in the facepiece cavity were compared according the the equations presented and a test apparatus consisting of an acetone generation and storage reservoir, a respirator test setup, and sample collection and analysis system. Sampling bias determined when in facepiece samples were collected during inhalation ranged from greater than -99 percent to more than +98 percent with a mean sampling bias of -17 percent. The range of fit factors for measured in facepiece concentrations was 44 to 4728. The actual fit factor was 87. The authors conclude that faceseal leakage is not mixing uniformly within the facepiece cavity, resulting in significant errors in estimates of within respirator sample concentrations.
NIOSH-Author; Personal-protective-equipment; Air-sampling; Air-contamination; Respiratory-protective-equipment; Sampling-methods; Air-sampling-techniques
Issue of Publication
American Industrial Hygiene Association Journal
Page last reviewed: June 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division