Sealing Properties of Close-Fitting Masks Worn Over Facial Hair

Recent studies of quick-don aviator masks have challenged the traditional view that beards promote unacceptable leaks in close-fitting masks, suggesting instead that adequate respiratory protection remains. This new review aims to establish an updated position based on all available studies of close-fitting masks in bearded users.

Systematic searches identified eligible studies that evaluated the seal of close-fitting masks, intended to achieve optimal respiratory protection, in the presence of facial hair. Study quality was graded against five criteria: 1) study design (controls); 2) mask testing schedule; 3) bearded cohort size; 4) leak measurement method; and 5) representative testing (increased ventilatory demand, movements, and speech). Consideration was given to data meta-analysis.

Of 21 discrete studies, 5 are rated high quality, 8 medium, and 8 low quality. Overwhelmingly, they indicate that facial hair can seriously degrade the performance of close-fitting masks, with relevant factors including beard age, hair length, and density. Early hair growth (days, possibly hours) can compromise seals at ambient gas supply pressure, with positive (safety) pressure supplies vulnerable to established beards, particularly at lower flow rates and increased ventilatory demands. Mask protection factors may degrade with facial hair by two or more orders of magnitude.

Safety-critical close-fitting masks require a skin-tight seal. Mask seal integrity with facial hair is highly variable between individuals, between masks, and from one wear to the next. Quick-don close-fitting oxygen masks, required in aviation emergencies, will not function reliably unless the user is clean-shaven where the mask seal contacts the skin. Connolly D, Sheppard-Hickey R, Powell D, Lupa H. Sealing properties of close-fitting masks worn over facial hair. Aerosp Med Hum Perform. 2025; 96(12):1069-1078.