Carbon dioxide (or CO2) is a colorless and odorless gas that is vital to life on Earth. Its nominal concentration is about 400 ppm (0.04 %). High level of CO2 leads to acidity and various health-related problems. That's why it's so essential to control CO2 concentration, especially in areas where you are spending most of your time - living room, bedroom, office, classroom. With CO2 Monitor Kit you will measure not only CO2 level but also temperature, humidity, and atmospheric pressure.