University of Michigan - Ann Arbor

In the opening post of a thread, Jose-Luis Jimenez criticized an image that several presenters used during a WHO webinar to explain modes of transmission. He argued that the image contained major errors that perpetuated misconceptions and identified its source as https://frontiersin.org/articles/10.3389/fpubh.2020.00163/full.

Jose-Luis Jimenez's critique of an image used at a WHO transmission webinar

"2/ First, cutpoint of falling to ground (droplets) vs. floating and being inhalable (aerosols) is ~50 um, not 5 um. 

Second, image gives impression that close proximity infection is all droplets. Aerosols only seem to infect at long range. Totally incorrect.

3/ Aerosol infect best at close proximity. See https://medscape.com/viewarticle/934837?src=uc_mscpedt&faf=1#vp_1 for further details and references. And see this corrected image.

4/ PS: when I bring up the fact that the 5 um cutoff defies the laws of physics, I often hear crickets from "the other side." Sound like if some people thought "microns, schmicrons", not important at all.

Remember that if 5 um = squirrel, 50 um = elephant. VERY different motion!

5/ This error is to an aerosol scientist what it would be to an ID physician if we confused a virus for a bacterium.  (And then, when corrected, replied "microbe, schmicrobe.")

This stuff **does matter** to understand transmission, and it is not "theoretical" or "academic.""

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