Adafruit SCD-40 - True CO2, Temperature and Humidity Sensor - STEMMA QT / QwiicThe SCD 40 is a photoacoustic "true" CO2 sensor that accurately measures the concentration of carbon dioxide (CO2) in ambient air. Unlike sensors like the SGP30, which approximate CO2 levels from VOC gas concentration, the SCD 40 directly measures CO2 in parts per million (PPM), making it a reliable tool for environmental sensing, air quality monitoring, scientific experiments, and ventilation studies. While it is larger and more expensive than some