Altos is a CO₂ sensor that indicates the quality of air indoors. The device is designed as a small health accessory that is easy to carry around. It is not sensitive to volatile organic compounds and therefore provides accurate data. The sensor shows, in an easy-to-understand way, the amount of good air in a room. When used in combination with an app, Altos sends push messages prompting users to ventilate the room if the level is too low.