The sensor requires environmental temperature and humidity for better results. The example above shows that several I2C sensors are connected on the same bus. They provide the necessary data. These sensors should be defined first. If they are defined after CCS811, environmental info will be ignored by CCS811.
You may also send temperature and humidity from a higher system.
Analog value: 65NNN where NNN is a humidity value, for example, 65050 for 50%. Humidity range: 0 … 50.
Analog value: 64NNN where NNN is a temperature value, shifted by 25. For example, 64000 for -25C, 64025 for 0C, 64050 for 25C. Temperature range: -25 … 100.
Analog value: 0 .. 63999 – baseline value (see docs for CCS811).