Are Surgical Masks better than Cloth?? Not if it’s 2-layer cotton
A recent report on a big study in Bangladesh (1) reported that masks help reduce virus spread and that surgical masks are better than cloth masks. This contradicts with another test report published by the Washington Post and the Smithsonian’s Conservation Institute and the NIST (National Institute of Standards and Technology) that 2-layer cotton masks have higher filtration than surgical masks in real-world humid conditions. (2)
What is going on?
Well, not all cloth masks are created equal. A good 2-layer cotton mask has been shown to have 60-95% filtering efficacy in dry conditions, and under humid conditions (like when we breathe), to perform EVEN BETTER than surgical masks. The cloth mask used in the Bangladeshi trial tested at only 37% filtering efficiency because it was a cloth mask of lower quality - it was a 60-40 cotton-poly blend, which the Smithsonian-NIST scientists specifically reported to be less efficient than 100% cotton masks. Therefore, it is no surprise that the Bangladeshi report showed surgical masks to be more efficient than the cotton-poly blend cloth mask.
It is unfortunate that news reports do not understand these differences and simply report that surgical masks are better than cloth masks, as if all cloth masks were the same. Surgical masks are creating a real environmental problem for our planet and don’t perform better than 2-layer 100% cotton masks, not to mention all the chemicals in surgical masks that we are breathing in and putting on our skins when we wear and breathe in them. We should be encouraging people to switch to 100% cotton masks.
Regardless of the choice of masks, what we agree on is that while the pandemic is still going on, we should wear a comfortable good quality mask when indoors and when in proximity to others, and try to open the windows as much as possible.
(1) “Normalizing community mask-wearing: a cluster randomized trial in Bangladesh” Working Paper 28734 by various authors, published by the national Bureau of Economic Research, April 2021
(2) The Washington Post, Mar 27, 2021. “What’s in all those masks?” Tests conducted by the National Institute of Standards and Technology (NIST) and the Smithsonian's Museum Conservation Institute.