The Relationship between Physical Attributes of Beard and Respirator Leak Rates

Abstract. The purpose of this study was to assess the effect of variousphysical attributes of beard on respirator leak rates in two ethnicgroups. Five study volunteers each of Middle Eastern and Anglo-Saxon ethnicity were selected for this study. They were asked not toshave for a period of two weeks and subjected to a daily leak ratemeasurement using a Control Negative Pressure (CNP) fit tester. Atthe end of the study the beard hair was collected and hair length anddiameter were measured to study the association between hair characteristicsand respirator leak rates.A significantly higher length and diameter was observed in theAnglo-Saxon group. However, the leak rate was not significantlydifferent between these ethnic groups. Independently, both hair lengthand diameter were not significantly correlated to leak rate but an interactionterm generated to explain the aspect ratio was inversely correlatedwith leak rate on day (r = 0.64, p-value = 0.048).The daily respirator leak rates increased exponentially over atwelve-day period with a significant change occurring between day 4and day 5. A second order regression equation was plotted toaccurately predict the respirator leak rate with the age of beard. Weconclude that beard hair attributes can be used to predict respiratorleak rate.