The Blueair Blue Signature Medium Nordic Fog is the best air purifier I've come across so far.
In particular, it has a large, effective filter, a sensor for both particles and VOCs, a great on-unit display system that only lights up when you move nearby, an excellent phone app for remote monitoring, control and scheduling... and my favorite : an effective yet extremely quiet fan!
My primary concern is noise level and noise character and the Blue Signature Medium is by far the best I've seen or heard. At the highest speed, the noise character is not obtrusive and it becomes much less so as it slows down to the usual Low speed. Low speed is very quiet and the sound is unobtrusive., so that even I can easily sleep near it in a quiet room. But it gets even better with Night mode, which can be set in schedule. where it becomes almost silent. The fan blade design is unique, being in between a blade fan and a squirrel cage blower.
The Blue Signature Medium has been performing brilliantly during the recent wildfire smoke, which is imperceptible indoors but quite obnoxious outdoors.
For me, the optional wooden leg stand is a must as it raises the Blue Signature Medium off of the floor and to a more pleasing height. As it just rests atop the stand, any small stool would suffice.
In comparison to other Blueair products I've experienced:
The DustMagnet 5410, while competent, lacks the VOC sensor and while reasonably quiet, the squirrel cage blower design is nowhere near…