The
evidences of benefit of wearing face masks in curbing the spread of
coronavirus in Asian countries may not be able to convince some
Americans. I'll present a collection of reports in various credible
scientific and medical journals showing the merit of wearing face
masks. On the 6/2/2020 Scientific American issue, there was a
comprehensive article of “How to use masks during coronavirus
pandemic”.
It
is not my intent to tell the technical aspect of the scientific basis
of wearing face mask, although it is available if one is interested
in this kind of “dry” stuff. There is an article on 9/21/2011
the
Proceedings of Royal Society A
with a title of “Effectiveness of facemasks to reduce exposure
hazards for airborne infections among general populations”.
https://royalsocietypublishing.org/doi/10.1098/rsif.2011.0537
Comparison
of paper surgical masks with fabric/cloth ones
Researchers
examined the materials under a microscope and noted fabric has a more
open structure with bigger holes (see the photo). Ideally a cloth
coverings should have at least two layers, which can trap more
particles than a single layer. I personally tend to wear a cloth
covering on top of a surgical mask inside.
Droplets
evaporate and become smaller and smaller as they flow through the
air, so they are the largest when they are first coughed or sneezed
out, this is why cloth mask with relatively “large” holes (under
microscope) still can do the job well, trapping the droplets,
preventing them airborne.
Wearing
face covering can reduce the wearer's risk of catching the virus by
65%
There
was a report on Medscape
on July 10, 2020, in which Dr. Dean Blumberg, chief of pediatric
infectious disease at UC Davis Children's Hospital, said that a
“standard rectangular surgical mask . . . will decrease the risk of
infection to the person wearing the mask by about 65%.”
Dr.
Blumberg likened those who don't believe masks work to not believe in
gravity. He also said not wearing face mask is an irresponsible
behavior, “it is like double-dipping in the guacamole. You are not
being nice to others.” President Trump encouraged his supporters
not to wear face masks, it is like sending his people into the battle
field without helmets.
To
be realistic, a surgical mask may not be able to trap aerosols, that
is why we also need to avoid the crowd and practice social
distancing.
The
surgical masks can reduce influenza virus RNA and coronavirus RNA in
aerosols
A
6/2/2020 Nature
Medicine
article shows that the surgical masks can reduce influenza virus RNA
and coronavirus RNA in aerosols, thus preventing transmission of
coronavirus and influenza viruses. The study was done on the exhaled
breath and coughs of children and adults with acute respiratory
illness due to seasonal human coronaviruses (not SARS-CoV-2) and
influenza viruses.
Hamsters
with masks are protected from coronavirus infection
A
study reported on May 2020 Clinical
Infectious Disease
showing hamsters wearing masks reduced coronavirus infections by more
than half comparing with those hamsters without using masks when
exposed to coronavirus.
The
studies showing benefits of wearing face masks abound
A
systemic review and beta analysis of 172 studies found that “face
mask use could result in a large reduction in risk of infection.”
This was published on 6/27/2020 Lancet.
An article in Health
Affairs revealed
that state mask mandates may have prevented more than 230,000
coronavirus infections.