Higher levels of CO2 in a building are an indicator of poor ventilation which increases the risk of COVID-19 spreading.
For this and other important reasons, a very useful tool is the bestseller wireless CO2, RH and Temperature data logger, model ΜΧ1102 by ONSET (U.S.A.).
For further info, see the following pdf:
On-line quality parameters monitoring systems
Water quality and meteorological station
Telemetry Network for Water discharge Measurement
Telemetric Hydrological Network