HEPA Air Filtration and Covid 19

Has it been conclusively demonstrated that HEPA air filtration devices reduce the transmission of Covid 19?

“ With new attention on the role that aerosolized microdroplets could play in the spread of COVID-19, should you rush out to buy a portable air cleaner for home use?

The frustrating short answer is, “It depends.”

Moved to the Quarantine Zone. This is COVID specific so seems like the better forum for it.

Please keep the answers factual as the Op is seeking facts not opinion.

Poop! Hoping for factual responses and not opinions.

Looks like the friendly ever-conscientious moderator has your back.

Air that has come through a HEPA filter will have at most 1/3000 the COVID-19 particle count that it did before it went through the filter. HEPA filters are 99.97% efficient at filtering particles that are 0.3 um in size, and they are more efficient on particles that are larger OR SMALLER. (it turns out that very small particles are quite easy to catch because they diffuse around so much, and the hardest size to catch is the “most penetrating particle size”).

The other necessary condition for a person to be safe is that they are breathing only the air that has been filtered or is otherwise clean, such as air drawn in from the outdoors. As you can imagine, it is very complicated to figure out whether, when a sick person exhales particles, will the HEPA filter inhale that air first, or will you?

Assuming you do not have sick people outdoors near the windows, a HEPA filter and an intake fan in the window both accomplish the same thing: they give you a stream of clean air. It’s not the HEPA filter or the window that determine what the people in the room do with the air, and how they might pass it among them.

That’s not to say HEPA filters aren’t very helpful. For one thing, winter is coming, and having a big fan in an open window isn’t an option if you don’t want the pipes to freeze.

Wish the mods would consider sliding this back into GQ. Answers could be potential helpful to others in addition to myself.

Thanks, Napier

I have been required to report back to work in my office since May. Fortunately I have a private office. Unfortunately the window doesn’t open, and winter is coming regardless.

This thread prompted me to buy a HEPA air filtration unit sized for a large room for my office. (I didn’t even bother wasting my time asking my work to buy me one.) It was in the back of my mind anyway after I saw that my dentist installed them in all of their patient rooms.

While I was at it, I got additional units for my house.

Thanks for the link to the NPR news story, @am77494. I know the article was somewhat equivocal about the benefits, but it convinced me.