PM2.5 is the particulates in the air with a diameter less than or equal to 2.5 microns. It usually carries heavy metals and microorganisms, and it stays in the air for a long time, which has a great impact on human health and the quality of the atmosphere. The PM2.5 sensor is able to detect the concentration of particulates in the air around us, observe the weather, and create an experimental environment.

Specifications
Connections: RJ11 4P4C
Power: 3.3V
Connections type: Digit output
You can find the introduction of this product following this link
https://wiki.elecfreaks.com/en/microbit/sensor/planet-x-sensors/Plant_X_EF05028