3 ms·
It’s worth noting that filter efficiency is a function of particulate size. A MERV13 and a HEPA filter are nearly equivalent for filtering pollen, but have dras
by bsilvereagle 5y ago
It’s worth noting that filter efficiency is a function of particulate size. A MERV13 and a HEPA filter are nearly equivalent for filtering pollen, but have drastically different performance for smoke and virus particles.
There’s a plot 1/3 of the way down the page that shows the curves:
https://frdmtoplay.com/nagivating-air-purification/ https://frdmtoplay.com/nagivating-air-purification/
- dragontamer 5y agoYeah, it's actually pretty complicated. MERV13 also needs less pressure, and a box fan is bad with pressure. If you stuck a HEPA filter on a box fan, it might only do 100cu feet of airflow. MERV13 is maybe 200. HEPA is designed for higher pressure centrifugal fans. MERV13 is likely the best balance for home made designs
- hammock 5y agoThere is a cubic design that people have been doing with HEPA filters (4 sides and a cardboard bottom) that solves the airflow issue.
- diebeforei485 5y ago"Virus particles" do not float free in the air to spread disease. It's usually mostly salt water aerosols with a few virus particles in them.
- cottager2 5y agoIs that known? I don’t think it’s been conclusively decided whether or not the virus spreads via aerosolized droplets or if it’s truly airborne.
- epgui 5y agoThey certainly can free-float, generally speaking, but SARS-CoV-2 in particular is indeed known to be mostly in droplets and aerosols. Personally, I’d caution not to over-generalize this fact.
- cma 5y agoThe smaller a droplet is, the quicker it evaporates due to increasing surface area ratio.