Day-to-Day and Movement-Dependent Variations of Quantitative Fit Tests for an Individual Wearing A Respirator

호흡기 보호구 착용시 움직임과 매일 착용에 따른 Fit Factors의 변화

The fit of a respirator to the face of an individual can be determined by a qualitative fit test (QLFT) or a quantitative fit test (QNFT). The pass/fail decision from a QLFT or QNFT for the same respirator on the same individual may vary from one wearing to the next, because the human facial features are complex and the respirator may not fit to the face in the same way every time it is worn. This study reports how the fit factors (FF) resulting from a QNFT on an individual vary from day to day and depend on the movements in the six fit test exercises. The reported FFs provide an objective and numerical basis (FF) which does not depend on the subject's voluntary or involuntary response. Four half-mask (H1-H4) and four full-facepiece respirators (F1-F4) were fit tested on one wearer 10 times a day for 5 days with a PortaCount (model 8010, TSI). The FFs obtained for each set of 10 fit tests on a specific day and 50 fit tests on five days involving one of the six exercise regimes have been recorded as log-normal distributions. All of the geometric standard deviations (GSD) of the overall FFs varied widely among every wearing and day except for H1 and F3, and the variability of the half-mask respirators was larger than that of the full-facepiece respirators. Among the six exercise regimes, reading or talking (RT) had markedly the lowest exercise FFs on the tested individual. Generally, there were significant differences between the first normal breathing (NB1) FFs and the remaining exercise FFs.