Techno Line WL 1020 Manuel D'utilisation page 27

TVOC and CO2 sensor information

TVOC and CO2 (CARBON dioxide) adopt metal oxide
sensors with long-term stability and low drift.

TVOC is the abbreviation of total volatile organic
compounds, containing thousands of compounds.

CO2, the sensor does not directly detect CO2 in the
environment, but the approximate value derived from other
relevant parameters of the sensor.
Air quality testing
When WL 1020 is powered by USB cable:

Air quality (TVOC) sensor will be turned on all the time.
When WL 1020 is powered by batteries:

Press and hold the "LICHT" button for 3 seconds to
activate the sensor. It will update and display the air quality
EN7