The 3-in-1 Dyson Purifier Humidify+Cool Formaldehyde combines intelligent sensing with an advanced filtration and humidification system to purify, humidify, and cool you. Three phases of purification sit within a fully sealed filtration and airflow system. So what goes inside, stays inside. A solid-state formaldehyde sensor and a unique catalytic filter detect and continuously destroy formaldehyde¹, an activated carbon filter removes gases and odors and a HEPA filter captures 99.97% of particles 0.3 microns in size. Then powerful Air Multiplier technology projects purified, hygienically humidified air throughout the room. For a healthier, more comfortable environment.