AIRCHECK is a precise air quality sensor that measures particle matter. Aircheck can be used indoors and outdoors, instantly, and continually. It reliably measures both PM10 (10 micrometers diameter) and PM2.5 (2.5 micrometers in diameter) particulate matter in micrograms per cubic meter. Particulate matter is composed of solid and liquid particles suspended in air. This includes dust, pollen, smoke, and other harmful pollutants. In many metropolitan areas, air pollution has reached harmful levels. AIRCHECK can warn you when it's not safe to do outdoor activities or when it is time to turn on your air purifier indoors.