For peace of mind, each machine comes with a one-year Dyson Guarantee. Senses and reports CO2 levels 1.44 inch LCD screen displays carbon dioxide readings and airflow mode – senses and reports air quality levels in real time Whole-machine HEPA 13 filtration2 Three phases of purification draw pollutants in from all directions. And the whole machine is fully sealed to HEPA H13 standard – so what goes in, stays in. Destroys formaldehyde, continuously3 The solid-state formaldehyde sensor works simultaneously with a selective catalytic oxidisation filter, to destroy formaldehyde molecules 500x smaller than 0.1 microns.