WHAT WE LOVE: In extensive Lab tests, this line of combo machines from Dyson was incredibly effective at cleaning the air and it also does a superb job maintaining ideal relative humidity. HOW IT WORKS: The superb air cleaning is a result of its True HEPA filtration (a must for air purifiers we recommend), which can remove particles down to 0.3 microns in size. Choose between auto mode, which monitors moisture levels for you, or manual mode, which is useful when you want to add a quick infusion of moisture into the air, say, on a cold winter night before going to bed.All of this functionality comes with a hefty price tag, not including the $80 filter replacements and $30 cleaning kits, which will be needed to keep the machine running smoothly, so this purifier may not be for everyone.