Medical masks are certified according to international or national standards (EN14683 or ASTM F2100) to ensure they offer predictable product performance when used by healthcare workers, according to risk and type of procedure performed in a healthcare setting.
In a 3-ply medical mask, the outer and inner layers are made of non-woven material, and the most important middle layer is a filter. The filtration efficiency of the middle layer is what defines the quality of a face mask. Designed for single use, a medical mask’s initial filtration (at least 95% droplet filtration), breath ability and, if required, fluid resistance are attributed to the type and layers of non-woven materials.
According to European standard EN14683, medical face masks can be categorized into four types; Type I, Type IR, Type II, and Type IIR. This classification is based on bacterial filtration efficiency (BFE), differential pressure (Delta P), microbial cleanliness, and splash resistance.
The WHO recommended that;
(1) healthcare workers,
(2) anyone with symptoms suggestive of COVID-19, including mildly ill people,
(3) people caring for suspect or confirmed cases of COVID-19 outside of health facilities,
(4) people aged 60 or over, and
(5) people with underlying health conditions should wear medical grade face masks.
In August 2020, the WHO announced that
healthcare workers should use fluid-resistant masks of EN14683 Type IIR with BFE >98%
and non-fluid resistant masks of EN14683 Type II with BFE >98%.
Patients should use masks of EN14683 Type I with BFE >95% or higher.