1/ Don't worry about terminology. Wear a mask. Do it!

Been reading arguments over discipline-specific semantics related to aerosols, airborne, droplets, etc., etc., for months. IMHO, these discussions in a public forum have been largely counter-productive.

2/ I am a licensed environmental engineer w/ a PhD who has done research on indoor air quality for 3 decades. Have my own terminology, what I know, what I say & write. But I am not going to force technical terms from my field onto J.Q. Public if it doesn't promote understanding.

3/ If we care about getting a message across we should avoid discipline-specific terminology that, when mixed with terminology from other disciplines, only confuses the message.

4/ Disagreements between disciplinary experts in public forums is counterproductive and confusing. I get asked a lot of questions about this terminology, or that are based on confusion because of terminology, in emails from the public and questions from the media.

5/ My experience has been the public tends to understand “tiny particles that stay in air a long time & that are so tiny they are invisible" & “large particles like spittle.” People get this. So I use these descriptions after many other iterations did not seem to stick as well.

6/ Not saying these are THE words everyone should use. But based on experience, the general public seems to get this more than droplets, droplet nuclei, aerosols, fine particles, respirable particles, & all the other things that many of us learned in grad aerosol courses.

7/ IMHO, we should save disagreements on terminology in forums other than twitter, perhaps allowing those of us in different disciplines to learn from one another, better understand one another, and maybe even start working with on another more.

8/ The rest of this is the kicker to me.

If a particle is emitted into the air, for however long it stays in the air (seconds to hours), it can be deposited in the respiratory system (somewhere between nose and deep lung [alveolar region]) of a receptor.

9/ Yes. How long it stays in air, where it deposits in our respiratory system, & how easy it is to control, all depend on the particle size. But let's not muddy the water (air?). The simple message is ......

10/ Outside of your own home, you should wear a mask indoors, period. It will protect you and others from both those very tiny particles that stay in air for a long time and large particles like spittle. Period.

11/ How darn wonderful is it that one highly inexpensive and simple “technology” can do both, and for all particle sizes in between to boot? Wear a mask. Period. Don’t worry about terminology used by a lot of experts in different disciplines. Wear a mask. Please, just do it.