Comment by ruralfam

I agree completely re: mev-13 == optimal solution. But the word "pragmatic" hits me hard. Merv-13 when new/clean start out with pretty restrictive flow. They catch a lot of particles so restriction increases rapidly. At some point the CFM loss means the filter is much less optimal. All the studies I read used new filters, smoke-filled rooms, a day's treatment. It is obviously impractical and very, very expensive to replace a merv-13 filter every few days. There are no reusable merv-13 filters that I could find. If there is a study about merv-13 effectiveness over 30 days vs. merv-8 I would love to see it. I would love to use merv-13, but just cannot get my head around how it is a practical, affordable solution across years and years of use, and let's say a month between filter renewal. Let me know if you have good insights as I am pretty worn out researching this. Thx, RF