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 designs of FFP3 and one-half mask were tested, selected from seven models of FFP3 and two half masks. Fit tests were carried out immediately after shaving and repeated six times 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. The statistical analysis predicted this could reach an unacceptable level for all the masks tested.