Facial Hair and Respirator Fit

Abstract No:


Abstract Type:

Professional Poster 


E Floyd1


1University of Oklahoma, Oklahoma city, OK


Dr. Evan Floyd, PhD  
University of Oklahoma


This scientific study explored the effect of facial hair on respirator fit using a single half mask elastomeric respirator. An attempt was made to quantitatively describe the effect of length, areal density (# hairs/ cm2) and coarseness (hair diameter) on respirator fit by controlling length and measuring density and coarseness.

Situation / Problem:

What is the effect of facial hair on respirator fit for a single model half mask elastomeric respirator. Improvements over other studies were: control of beard length by using a beard trimmer instead of days of growth, measurement of hair areal density and diameter instead of qualitative grading.


20 bearded subjects were recruited across an age range of 18-65. Each subject was trained in respirator use according to the OSHA guidelines and performed a preliminary fit test to determine the correct size respirator as best as possible with a full beard. Subjects were fit tested in three independent fit tests at each of five beard lengths. Beard lengths were obtained with a beard trimmer and finally shaved with a razor. A hair sample was collected between 1/8 inch and stubble for diameter determination by light microscope. After the stubble condition was achieved areal density was measured under the chin and on the cheek even with the corner of mouth. Fit Factor (FF) values were converted to penetration values and the effect of hair length, density and coarseness were evaluated using a mixed linear model in SAS.

Results / Conclusions:

Facial hair was negatively correlated with FF, especially beyond 1/8 inch length. However, all subjects achieved passing FF scores for clean shave and stubble conditions with no statistical difference between the two conditions. 98% of all fit tests were passed at 1/8 inch length, and 58% of fit tests passed at 1/2 inch length. Beard coarseness (hair diameter) was not a significant parameter in our model, though we think it should be measured in future studies as it may prove significant with larger sample sizes. Areal density (# hairs/ cm2) was weakly negatively correlated with FF (R =0.264), meaning that as more hairs were present per cm2, the respirator tended to leak more. By far, the most important beard parameter was length. In conclusion, facial hair does reduce respirator fit quality, however many half-mask elastomeric respirators provide FF scores well above the required 100. In this study 98% of fit tests were passed at 1/8 inch beard length and 7 out of 19 subjects never failed a single fit test through 1/2 inch. Is it time for OSHA to consider relaxing the clean shaven rule to allow a modest amount of facial hair with demonstrated respirator fit?

Primary Topic:

Respiratory Protection

Secondary Topics:

Personal Protective Clothing & Equipment
Social Concerns

Acknowledgements and References

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