Over thirty years ago, I wrote my doctoral dissertation about tiny airborne particles. Since then, I have taught at the university level many courses about atmospheric chemistry, including aerosol formation and the fate of such tiny invisible particles.
We know that face masks work best for larger droplets. While we speak or cough, we spit out many droplets, mostly between 10 – 1000 micrometer. For comparison, a hair has a diameter of about 50 micrometer. Droplets when expelled from our mouth start vaporizing very quickly, within just a few seconds they shrink to sub-micron dimensions. At those small droplet sizes or naked corona virus size, face masks have a very low capture efficiency, in part due to the fact that those tiny droplets are highly mobile and travel by the least way of resistance, around your mask and through the gap between mask and face where tightness is limited.
Hence, it is important for EVERYBODY to wear a mask, even in public. This is especially important in winter, when droplets stay around longer, cold weather enhances survival rate of the COVID virus and UV radiation from the sun is limited. What’s the difference between accidentally flying bullets or airborne deadly viruses? Potentially, both kill.
I was recently in San Luis Obispo, a city where every 200 yards or so a poster indicates that mask wearing in public is required, yet not enforced!
What does it help when glorified individualism is valued above common sense and regard for others? A person can unknowingly be COVID positive and infecting other people. Just saying: “wear a mask if you want to protect yourself, but don’t tell me what to do” is unfortunately not very effective. Just yesterday, the COVID related death rate was over 4000 in the “Ununited States of America”. By the way, the lady in the picture is holding her mask safely in her hand.
Fortunately, there are others who care! When will mask wearing be enforced…?