2 ms·
This is a mathematical model, not a study of empirical data. It's worth distinguishing, because models are only as good as their assumptions. The model presume
by cheald 5y ago
This is a mathematical model, not a study of empirical data. It's worth distinguishing, because models are only as good as their assumptions.
The model presumes a "filtration constant" for masks, which only apply for pressure-sealed masks, like properly-fitted N95s. Simple face coverings don't do much to protect you against aerosols, for the same reason that they don't do much to mitigate the effects of attempting to breathe in a smoke-filled room - the airflow is just redirected through the sides and top of the mask, rather than being filtered. So, while the results may have some value for N95s, I seriously question their value for "masks" as they are currently colloquially understood.
- toomim 5y agoA filtration constant can apply to poorly-fitted masks, too. They just have a smaller constant. The filtration constant for a well-sealed N95 can be 99.99%. The filtration constant for a thin cotton "face covering" can be 20%. The point isn't that the model doesn't apply to poor masks -- it's that they have poor constants. We will do much better to include them in the model, and then mathematically predict how important it is to improve your filtration constant, than to say "those masks don't apply" and throw up our hands at quantifying the improvement that could be gained by better masks.