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Surgical mask medical face mask personal protective equipment

Surgical mask medical face mask personal protective equipment

surgical mask, also known as a medical face mask, is a personal protective equipment worn by health professionals during medical procedures. It prevents airborne transmission of infections between patients and/or treating personnel by blocking the transmisson of pathgens (primarily bacteria and viruses) shed in respiratory droplets and aerosols into and from the wearer's mouth and nose.

Surgical masks are made of a nonwoven fabric created using a melt blowing process. They came into use in the 1960s and largely replaced cloth facemasks in developed countries. The dark blue (or green) side of the mask (the fluid-repellant layer) is to be worn outward, with the white (absorbent) layer on the inside. With respect to some infections like influenza surgical masks could be as effective (or ineffective) as respirators, such as N95 or FFP masks; though the latter provide better protection in laboratory experiments due to their material, shape and tight seal.

Physical form

The design of the surgical masks depends on the mode; usually, the masks are three-ply (three layers). This three-ply material is made up of a melt-blown polymer, most commonly polypropylene, placed between non-woven fabric.The melt-blown material acts as the filter that stops microbes from entering or exiting the mask.Pleats are commonly used to allow the user to expand the mask such that it covers the area from the nose to the chin. The masks are secured to the head with ear loops, head ties, or elastic straps.

Physical properties and quality

Performance of surgical masks is evaluated based on such parameters as filtration (mask capture of exhaled aerosols), exposure (transfer of aerosols from outside), mask airflow resistance (pressure difference during breathing, ΔP, also known as breathability), liquid penetration resistance, air and water vapor permeability, water repellency (for outer and inner surfaces).

Filtration and exposure is typically measured in bacterial filtration efficiency (BFE) using particles of size 3.0 μm. Particulate filtration efficiency (PFE) using particles of size 0.3 μm is only measured in China.

Physical properties of surgical masks
Parameter Typical unit
Pressure differential, ∆P cm of H2O / cm2
Filtration and exposure %
Liquid penetration resistance mbar
Air permeability ml/s⋅cm2 at 100 Pa
Water vapor permeability g/24 hr⋅cm2
Water repellency grade

 

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