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Due to the epidemic of covid-19, I have to work from home. In the winter, I have to close the doors and windows. The longer I stay in, the higher levels of CO2 increases, that made me a bit dizzy and lazy. Although CO2 is a harmless gas, people in high concentrations of CO2 for a long time will be harmful to health: Around 1000 ppm, a common indoor level, you will start to experience fatigue and sleepiness; For upto 2000 ppm, you will fall into sleep and feel really tired, that cant go on any work. With prolonged exposure and increases in concentration, you may have a headache and feel physically uncomfortable.
Monitoring the indoor CO2 Level may actually be more important than our common sense, so I made a CO2 monitor show the indoor CO2 level reminds me to open the door and windows timely for improving the indoor air.

At room temperature, carbon dioxide (CO2) is a colorless, odorless, non-flammable gas, that must have a specific sensor to monitor it. SGP30 is a gas sensor intended for indoor air quality monitoring. SGP30 can detect a wide range of H2 and return an equivalent carbon dioxide reading calculated based on H2 concentration to the microcontroller over I2C. SGP30 has an ability to set humidity compensation for better accuracy, that it needs an external humidity sensor to work with. Besides, the SGP30 sensor can detect a wide range of Volatile Organic Compounds (VOCs) and return a total volatile organic compound (TVOC) reading.

I used the AM2302 to work with SGP30. AM2302 is a digital temperature and humidity sensor, it’s very common and easy to use.”

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