DIY air purifiers using a fan and Merv filter
HOW TO MAKE a do-it-yourself air-purifier by attaching a (replacement) HEPA filter intended for a furnace or a regular air purifier onto the front of a flat-faced box fan (or presumably other fan), for bedrooms or other places: https://smartairfilters.com/ en/blog/how-to-make-diy-air- purifier .....geeky stuff about why putting filter on the front is better than on the back , which filterscapture/etc what, etc: https://www.quora.com/Where- should-an-air-filter-be- placed-relative-to-the-fan- for-best-efficiency/answer/ Thomas-Talhelm and: https://smartairfilters.com/ en/blog/what-combination-of- air-filters-do-i-need-to- protect-against-everything "Merv" is the designation used (for furnace/HVAC filters...one brand ?) to indicate the rate the filter captures the lowest-micron sizes. " Merv 13 " is the highest rating, according to one person. They're also HEPA fi...