Erm, this isn't quite correct:
1) MERV14 will capture 75%-84% of particles in the 0.3-1μ range.
2) A filter which captures 70% of particles with an air flow of 100cfm will capture the same amount of virus as a filter which captures 100% of particles with an air flow of 70cfm. Both will clean the room just as fast. For air filters, lower filtration + higher airflow is usually a better design option. Going from 70% to 95% to 99.9% means you'll have a more expensive, power-hungry, and more noisy product over one which just has a little bit more air velocity [1].
3) The rating is for 0.3μ since that's the hardest size to capture. A filter will actually capture more particles below 0.3μ.
4) COVID19 virus particles are around 0.1-0.2μ, but that's beside the point. They're travelling on water molecules. Those are much bigger.
5) Even if there were a virus particle somehow floating around, a viral load of one virus is very unlikely to get you sick.
From an engineering standpoint, something around MERV14 is almost certainly the sweet spot for a COVID19 room air filter.
[1] High-filtrations makes sense in places like vacuums, face masks, and other places where the goal is to have clean air coming out. Vacuums shouldn't blow up dust. That's a different engineering design goal than a room air filter. If you'd like to see the impact of loading on a fan, put your hand behind one, and hear how much noise goes up. MERV14 has a much lower load than HEPA.
1) MERV14 will capture 75%-84% of particles in the 0.3-1μ range.
2) A filter which captures 70% of particles with an air flow of 100cfm will capture the same amount of virus as a filter which captures 100% of particles with an air flow of 70cfm. Both will clean the room just as fast. For air filters, lower filtration + higher airflow is usually a better design option. Going from 70% to 95% to 99.9% means you'll have a more expensive, power-hungry, and more noisy product over one which just has a little bit more air velocity [1].
3) The rating is for 0.3μ since that's the hardest size to capture. A filter will actually capture more particles below 0.3μ.
4) COVID19 virus particles are around 0.1-0.2μ, but that's beside the point. They're travelling on water molecules. Those are much bigger.
5) Even if there were a virus particle somehow floating around, a viral load of one virus is very unlikely to get you sick.
From an engineering standpoint, something around MERV14 is almost certainly the sweet spot for a COVID19 room air filter.
[1] High-filtrations makes sense in places like vacuums, face masks, and other places where the goal is to have clean air coming out. Vacuums shouldn't blow up dust. That's a different engineering design goal than a room air filter. If you'd like to see the impact of loading on a fan, put your hand behind one, and hear how much noise goes up. MERV14 has a much lower load than HEPA.