It’s a spreadsheet for various locations, comparing air purifiers by price, Clean Air Delivery Rate (CADR), and noise. Including useful stats like price/CADR, and CADR/dB. I’m so so so going to be using this!
@yosh I like that they include the DIY option of a 3M filter and a Lasko box fan, which outperformed many expensive options at a fraction of the price: