If the only metrics you are comparing is price and purification level, then of course you won't want a Dyson. But there are other important objective metrics su

If the only metrics you are comparing is price and purification level, then of course you won't want a Dyson. But there are other important objective metrics such as size and loudness which deserve to be a part of any scientific comparison. If the box fan is bigger and 4x as noisy, it's not a valid comparison for many situations. Instead should compare fans which are similar sizes and operating at similar noise levels. I have a Dyson fan and a box fan (not air purifiers), and the Dyson fan is significantly quieter, smaller (same height but about half as wide), while having a similar power (not exactly sure which one is stronger).