CO2 measuring device with traffic light indicator, temperature, and humidity display. Good ventilation of rooms reduces the risk of infection and enhances concentration. With the LogiLink CO2 measuring device, you always have a perfect overview of indoor air quality and know when it's time to ventilate. A concentration of under 1000 ppm is considered hygienically safe. A concentration between 1000 and 2000 ppm is classified as critical by the Federal Environment Agency, and anything above that is deemed unacceptable. However, with the large LCD display, you can not only read the CO2 concentration. The built-in data logger also measures temperature and humidity in weekly, daily, hourly, and minute intervals.