The SGP30 is an indoor air quality sensor equipped with an I2C interface. It outputs equivalent CO2 in ppm and Total Volatile Organic Compounds (TVOC) in ppb. The sensor also gives access to its raw measurement values of Ethanol and H2.
The SGP30 boasts high stability with low long term drift. With its continuous baseline compensation algorithm, readings stay accurate over time. You can even fine tune your readings by interfacing with an external humidity sensor to add humidity compensation.
While the CCS811 requires a burn-in of 48 hours and a run-in of 20 minutes the SGP30 is ready to go after just 15 seconds.
Sparkfun has written an Arduino library to help you get started quickly. Search for SparkFun SGP30 in the library manager.