ESP 8266 software to publish the readings from Airgradient sensors to your MQTT Server.
AirGradient Project: http://airgradient.com/diy/
Based on the original AirGradient esp software: https://github.com/airgradienthq/arduino/blob/master/examples/C02_PM_SHT_OLED_WIFI/C02_PM_SHT_OLED_WIFI.ino
In comparison to the original build the display has been removed but you can easily add the display capability by copying the corresponding lines from the ogiginal code into this sketch.