The CDC claims that the better a mask fits, the fewer aerosols and particulates escape past it. But viruses are not aerosols or particulates. In the trial person one is coughing or breathing. Person two from whom aerosols were measured wore two masks. They wore a cloth mask over a medical procedure mask.
The first person was exposed to 96.4% less aerosol from person two. But the presence of aerosol is not a surrogate for the virus.
One problem is this study only tested one type of procedure mask and one type of cloth mask. Hard to believe we don’t all have and use those specific masks. Procedure masks are fairly standard. But the market for cloth masks includes an endless variety of fabrics and forms.
Outside of the ideal conditions of a laboratory life happens. Someone who opts to wear a cloth mask on top of a procedure mask can lose all the benefits of improved filtration. All it takes is for the cloth mask to be a poor fit to the face. If the cloth mask has a poor fit, it would do nothing to improve filtration. When that is true the purpose of the double mask is defeated.
Another issue is the aerosols in the experiment are not an exact representation of viral particles. They were an approximation of a person’s respiration. How infectious a person’s respirations depends on their viral load. Therefore, a reduction in exposure does not necessarily mean the same reduction in infectiousness. Is infectiousness important?
What the study authors say about their findings
The study authors recognize these findings are not to be interpreted: “as being representative of the effectiveness of these masks when worn in real-world settings.”
Reducing the point of the study to simply a trial of the effects of double masking is a misrepresentation. It is far too narrow an interpretation. The results only speak to the effectiveness of the particular masks in the study as fitted in the study.
Every person has a unique face. Masking, double-masking, or other modified mask-wearing might all work to varying degrees. Or it might not work at all depending on the conditions. The only true conclusion from this study is that better fitting masks filter our breath better.
To that end, wearing a properly fitted N95 respirator would better than double-masking. The greatest potential utility of masks is: When people with the virus find themselves in situations where physical distancing from strangers is impossible. Masks were only ever meant to be part of a broad mitigation strategy. They were never meant to seal us off from the dangers of the world. They aren’t a cure-all.
An effective response requires understanding which measures work
If people want to wear two masks, go for it. If you want to wear three, more power to you. But masks only make up one part of a broader mitigation strategy. That strategy should include assessing risks, social distancing, testing, and vaccinating.
Policymakers should remember this. We should not rely on masks and making them even more repugnant to use. Policymakers should explore additional options. The options should include widespread rapid self-testing. This is an even more promising way to battle the pandemic.
It has been over a year now since Covid-19 first came to our shores. Americans were told to avoid buying masks, then to wear masks and now to wear two masks. Make up my freaking mind. In 2020 we come to understand the virus. At no point did we learn that masks would be anything other than an additive to better, more effective measures.
Masking: If one is good, how many is too many? The simple fact of the matter is: Doubling up on masks is doubling down on one of the least effective measures we now have. Heresy, right? You really should grasp the science before deciding who is making sense. Do your own homework.