I see the anti-mask crowd has latched onto a few studies to support the "masks don't help" train of thought.
As a data scientist however, I caution that none of these studies reached that conclusion and in most cases imply the exact opposite 1/14
This study randomized which wing of a hospital used medical masks (presuming N95 type) and which used cloth masks.
Relative Risk (of contracing influenza w/in 4 weeks):
•cloth mask: 13%
•medical mask: 6.64%
pubmed.ncbi.nlm.nih.gov/25903751/
They suggest that reusing a cloth mask may increase risks, but this was not tested.
pubmed.ncbi.nlm.nih.gov/25903751/
This study had patients cough into petri dishes without a mask, with a surgical mask, and with cloth mask.
Viral load for each:
•no mask: 2.56
•surgical mask: 2.42 (94%)
•cotton mask: 1.85 (72%)
acpjournals.org/doi/10.7326/M2…
•did not test for reducing transmission or contaminant dispersal beyond the petri dish (duration airborne or surface area covered)
•cloth masks catch some (25%) of the viral load when coughing
acpjournals.org/doi/10.7326/M2…
Studied which fabrics (if any) make the best homemade mask for protecting its wearer by measuring its ability to prevent very small particles (such as aerosalized COVID-19) from reaching the exterior of the mask.
academic.oup.com/annweh/article…
academic.oup.com/annweh/article…
Studied effectiveness on common surgical masks by "non-scrubbed" personnel in the operating room.
anesthesiology.pubs.asahq.org/article.aspx?a…
anesthesiology.pubs.asahq.org/article.aspx?a…
While that answer is still TBD, any efforts that reduce airborne and physical contamination should reduce the number of exposures and the viral load of each.
1-none of these articles concluded wearing a mask is not helpful
2-the first, second, and third article each proved that masks reduce both airborne and physical contamination by capturing some of the virus
1-reducing contaminated area reduces likelihood for transmission
2-cloth masks capture some of the germs (see #1)
3-cloth masks reduce velocity (see #1)
Note: this only shows that at least SOME of the virus is contained, not all of it