HSE Inspectors routinely come across workers with various degrees of stubble growth using respiratory protective masks, despite guidance to the contrary. This research studied the effect of 0-7 days stubble growth on the protection given by FFP3 filtering facepieces and half masks.
Fifteen male volunteers took part, each testing four masks. For most, three different design FFP3 and one half mask were tested, selected from seven models of FFP3 and 2 half masks. Fit tests were carried out immediately after shaving and repeated six times during the following week, without further shaving.
Results showed that the effect on protection was quite specific to the mask/wearer combination. Protection could be significantly reduced where stubble was present, beginning within 24 hours from shaving, and generally worsening as facial hair grew. Statistical analysis predicted this could reach an unacceptable level for all of the masks tested.
While some individual wearers did grow some stubble without significantly reducing protection with some masks, this was unpredictable and it would not be practical to conduct the necessary testing to confirm this for every individual wearer.
The current guidance advising being clean-shaven in the area of the mask seal is justified.
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