“Each box typically costs under $100 to make and is more effective than other, pricier options like High Efficiency Particulate Air filters....The simple contraption consists of a box fan, four MERV13 furnace filters that can be purchased online or in store, some cardboard and strips of tape.
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I’m missing something here....
According to the EPA, a HEPA filter is defined as being “theoretically able to remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns (µm).” Meanwhile, a MERV 13 filter rating is that it has a “removal efficiency of 50% for particles in the 0.3 to 1.0 micron size.”
So I guess this claim all hinges on what the word ‘effective’ means? In the meantime, the covid19 virus particles are supposedly in the 0.1 micron size in which case, one better hope that the are always attached to something larger....
