Two top-notch indoor air quality sensors, the SCD41 and SEN55 from SensirionTM, are combined in the SparkFun Indoor Air Quality Sensor-SCD41, SEN55 (Qwiic). These sensors offer a complete indoor air quality sensor that measures temperature, relative humidity, particulate matter (PM1.0, 2.5, 4, and 10), CO2, and volatile organic compounds (VOCs). In order to detect concentrations from 0 to 40000 ppm with high accuracy over 400-5000 ppm ± (40 ppm+5%), the SCD41 uses Sensirion's PASens® photoacoustic measurement system, which combines narrow-band infrared light with a microphone inside the sensing package. To increase accuracy, the SCD41 incorporates a CMOS® sensor for temperature and humidity. The SCD41 also takes ambient pressure readings for extra precision! Over the course of a seven-day calibration, the SCD41's automatic self-calibration routine adapts to its sensing environment.