This is a case for non-commercial Air quality measurement. It provides an indicator based on CO² concentration in the air.So it gives a hint that it is time to open the windows and ventilate.
Parts needed: - Wemos D1 Mini - CO² Sensor MH-z19 - LED Ring 12 x WS 2818 or similar (inner diameter of at least 35mm and outer diameter of maximum 54mm) - 30mm x 30mm fan, 5 V
Make sure to burn in the CO² sensor when using it for the first time. The measurement results in the first 30 minutes of initial use are not representative. After that, the measured values are correct (due to the sensor) about 5 minutes after switching on. The Aircare box should be placed in the middle of the room if possible, but not at the window.
Depending on the sketch used, the Aircare box can be used standalone or send its measured values via MQTT, for example to Grafana in your own network.