@xiroux@zaidin.lgbt Here's one that compares different CR Box designs to a commercial HEPA: https://www.texairfilters.com/comparing-the-performance-of-corsi-rosenthal-boxes-made-with-box-fans-and-pc-fans/ This write-up points out some pros & cons while highlighting use-cases where HEPAs are still important, like hospitals: https://blog.activepure.com/corsi-rosenthal-box-vs-air-purifiers/ Here, a CR Box is compared to a couple of commercial HEPA air cleaners with a focus on use in classrooms: https://itsairborne.com/comparing-hepa-filters-and-the-corsi-rosenthal-box-a8b6d03af905 And to find even more, you could try web searching something like: Corsi Rosenthal Box compared to HEPA.