California issued a statewide mask mandate in June 2020. Rhode Island issued its mandate back in May 2020, as did neighboring Connecticut in April 2020. What else do these states have in common? They were among leaders in COVID-19 cases, hospitalizations, and deaths long after implementing their mandates. Were they infected by nearby states? New York, New Jersey, Massachusetts, Oregon, and many counties in Nevada and Arizona also had mask mandates.
Florida did not have a statewide mask mandate. Nor did Montana, South Dakota, Wyoming, Iowa, Missouri, or Oklahoma. Other states like North Dakota, Arizona, and Indiana issued short-term mask mandates. These states fared no worse and in most cases fared far better than states with mask mandates. Why would this be, if face masks work?
Viral particles that spread in the air vary in size. A micron, or micrometer, is represented by the symbol μm. A micron is defined as one-millionth of a meter, a little more than 1/25,000th of an inch. A large droplet is defined as 5 μm or larger. You can’t see a 5-μm droplet. Many people visualize a droplet housing a virus as something you can see, like something you’d sneeze out. Certainly droplets can be sneezed out, but that’s not where real transmission happens. You can easily block those, and if they become airborne, they drop to the nearest surface in seconds.
Airborne transmission has often been attributed to infectious droplet nuclei produced by the dessication of suspended droplets, defined as 5 μm or smaller in size.
Infectious aerosols are suspensions of pathogens in particles in the air, subject to both physical and biological laws. Particle size is the most important determinant of aerosol behavior. Particles that are 5 μm or smaller in size can remain airborne indefinitely under most indoor conditions unless there is removal due to air currents or dilution by ventilation. Particles sized 6–12 μm deposit in the upper airways of the head and neck.
The studies reviewed in this paper consistently show that humans produce infectious aerosols in a wide range of particle sizes, but pathogens predominate in small particles <5 μm that are immediately respirable by exposed individuals.
The figure above shows that 87% of exhaled particles are under 1 μm, and this is why masks have not worked. A peer-reviewed study called “Optical microscopic study of surface morphology and filtering efficiency of face masks” was published in June 2020 in the National Center for Biotechnology Information and filed in the National Institutes of Health library. In this study they found that the pore size of face masks hovered about 80-500 times larger than a SARS-CoV-2 aerosol particle:
The pore size of cloth masks ranged from 80 to 500 μm. Interestingly, we found that efficiency dropped by 20% after the 4th washing and drying cycle. We observed a change in pore size and shape and a decrease in microfibers within the pores after washing. Stretching of cloth mask surface also altered the pore size and potentially decreased the filtering efficiency. As compared to cloth masks, the less frequently used surgical/paper masks had complicated networks of fibers and much smaller pores in multiple layers in comparison to cloth masks, and therefore had better filtering efficiency. This study showed that the filtering efficiency of cloth face masks were relatively lower, and washing and drying practices deteriorated the efficiency.
Below is an image of two cloth face masks before and after stretching:
What you see is that in the cloth mask A (before stretching or washing), the pore size is about 250 μm. After stretching (which happens when we put it on our face stretched ear-to-ear), the pore size is maybe 400 μm. This is why the average face mask Americans are wearing don’t work: It’s all in the math.