New research presented at this year’s European Congress of Clinical
Microbiology & Infectious Diseases (ECCMID), held online this year
(9-12 July), shows that wearing a surgical face mask can provide a
similar degree of protection against aerosols as wearing a respirator.
Face shields, however, provide little or no protection.To get more news
about
Quality Medical Mask, you can visit tnkme.com official website.
The
efficacy of personal protective equipment (PPE), including face masks,
has been the focus of scientific and public interest since emergence of
the SARS-CoV-2, a virus which is mainly transmitted through droplets and
aerosols in poorly ventilated settings. It is crucial to provide
healthcare workers with high-quality face masks or respirators to
protect both themselves and their patients. However, at start of the
pandemic, some experts, particularly in Europe, said that while surgical
face masks protect others, they provide no significant protection for
the wearer. Moreover, many newly produced masks seem to be of poor
quality.
The study, by Dr. Christian Sterr and colleagues at
Philipps University Marburg, Marburg, Germany, compared 32 types of mask
intended for use in hospitals, including cloth and surgical (medical)
masks, respirators and face shields. The surgical masks included some
with EN 14683 certification (the EU quality standard) and others that
were non-certified. Both FFP2 and KN95 respirators were tested. KN95
respirators, which meet Chinese standards, were subject to EU RAPEX
safety warnings from April 2020.
The first experiment measured the
filtration efficacy of the mask material. Each mask was fixed to an
air-collecting tube inside an airtight tank. An aerosol of the chemical
di-ethyl-hexyl-sebacat (DEHS) was pumped into the tank and the aerosol
particles in the collecting tube counted by a particle counter.
The
average filtration efficacy was lowest for the cloth masks (28%),
followed by the non-certified surgical masks (63%) and the certified
surgical masks (70%). The KN95 respirator material filtered out 94% of
particles and the FFP2 mask material, 98%.
The second experiment
measured the air pressure on either side of the mask. Surgical face
masks produced the lowest drop in pressure and so would provide the
least resistance to breathing—type II surgical masks produced a pressure
drop of 12.9 Pa/cm2, while non-certified surgical masks produced a
pressure drop of 16.2 Pa/cm2.Respirators produced pressure drops that
were two to three times higher (26.8 Pa/cm2 for FFP2 and 32.3 Pa/cm2 for
KN95). The results for the cloth masks ranged between 6.9 and 149.3
Pa/cm2.
The third experiment measured the filtration efficacy of
the masks as worn. It used a similar set-up to the first experiment but
the masks were mounted on a dummy head with an artificial trachea or
windpipe, instead of being fixed to the air-collecting tube. The
artificial head was the size of the average person in the US and had a
skin-like coating, to provide a more realistic mask fit.
The cloth
masks and the non-certified surgical masks had the worst as-worn
filtration efficacies, filtering out just 11.3% and 14.2% of the
particles, respectively. Remarkably, the type II surgical face masks had
similar as-worn filtration results (47%) to the KN95 respirators (41%)
and FFP2 respirators (65%). The face shields did not have any
significant effect.
