An Arduino Uno, slightly modified (it isn’t necessary). It is basically an Arduino Uno, with duplicated pins alongside 5V and GND for each one.
NO2 & CO Sensor MiCS-4514
High sensitivity NO2 & CO measuring sensor. Datasheet.
Ks0196 keyestudio PM2.5 Shield
Dust sensor, able to measure particles greater than 2.5 microns in size.
DTH11 sensor, able to measure temperature and humidity.
Esp-8266 Wifi Module
WiFi module for communication between Arduino and ThingSpeak.
Here are some photos that we have taken of the sensor.