Do you want to know the quality of the air in your room or house? The SparkFun Air Quality Sensor - SGP30 (Qwiic) may be just the sensor you need. Indoor air quality (referred to as IAQ) sensors are great for measuring equivalent CO2 and volatile organic compounts (commonly referred to as VOCs)
Along with a very quick start-up time, the SGP30 is very resistant to contamination from other gases to ensure low drift and long-term stability for extremely reliable results. To cap it all off, you can also read the SGP30's raw measurements of ethanol and H2.
When connected to your microcontroller (running Sparkfun's SGP30 library code) it will return a Total Volatile Organic Compound (TVOC) reading and an equivalent carbon dioxide reading (eCO2) over I2C.
More information is available on the website of Sparkfun.