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KMID : 0381319950340040133
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Korean Journal of Occupational Health
1995 Volume.34 No. 4 p.133 ~ p.143
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Quantitative Respirator Fit Testing of Half Mask Respirators
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Abstract
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This study was designed to quantitatively examine the degree of fitness between the facepiece of half mask respirators and its user´s face. Total 40 subjects(20 males and 20 females) were volunteered to participate the experiment. Three domestic brands and three U.S.A. brands of imported half masks were selected for the study and the fit factors(FF) were obtained using a condensation nuclei counter, the Ports Count Plus(TSI, USA Model 8020).
The obtained FF were analyzed by gender, manufacturer, origin, facial size, exercise, size of mask´s deadspace, and number of filters. In addition, subjective feelings about each respirator worn were also surveyed.
The results were as follows:
1. Facial dimensions of male subjects including face width, face length, nose length, nose height, lower face length, and lip width were statistically larger than those of female subjects. FFs obtained from subjects with larger face width, lip width, and face length were statistically higher than those of from subjects with smaller dimensions.
2. FFs obtained were 25591.10 from imported masks d 38.86 from domestic ones, and was significantly different. Larger FFs were obtained from male subjects in domestic masks while female subjects had larger FFs in imported ones.
3. FFs obtained while performing different exercises were statistically significantly different for both masks. For domestic masks, the largest FF of 125.21 was obtained from reading while the smallest FF of 27.94 was found when the face was moving side to side. In constrast, the largest FF of 171099.41 was observed with normal breathing while the smallest FF of 982.40 was measured with reading for imported ones.
4. For domestic brands, masks with larger mask deadspace and made of soft material had statistically very significantly larger FFs.
5. FFs obtained from a domestic brand mask with single and twin filter were 202.35 and 17.46, respectively and were statistically significantly different.
6. No statistically significant difference of FFs between fixed and free types of head band was found.
In conclusion, this study suggests that masks with different sizes should be supplied to workers so that they have an opportunity to select the most comfortable and well fit respirator to enhance fit factors. Since such dimensions as face width, face length, and lip width were identified as main variables affecting fit factors, these variables should be considered in the manufacture of half mask respirators. It is also recommended that the face piece be made from soft and light in weigh material and the weight of filters be kept as light as possible. Additionally, fit testing should be incorporated into the current test battery of respirator performance certification test. Further studies of protection factors in the actual workplaces should be conducted in the near future.
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