How to access the CCI air quality data

We have several AirGradient indoor and outdoor air quality sensors at the Greencoat building, which log data every 30 seconds via MQTT and are available to students and staff who want to access this data.

MQTT Server

The MQTT server sits at mqtt.cci.arts.ac.uk on port 1883.

The read-only student username and password can be provided by asking on Slack in the #technical channel.

Data format

The data format is airgradient/readings/(sensor), the sensors is the MAC address and serial number of that location, the locations are:

Greencoat

• GB_G03 = 0cb815082660
• GB_G04 = 4022d8f9b4d8

Peckham Road

• PR_B501-01 = dc5475bb845c
• PR_B501-02 = b48a0a613900
• PR_B501-03 = dc5475bcc430

High Holborn

• HH_302 = dc5475bce770
• HH_308 = dc5475bacb84

Example data:

{
  "firmware":"9.3.0",
  "wifi":-39,
  "ssid":"UAL-IoT",
  "light":4095,
  "hwVersion":8,
  "rco2":409,
  "atmp":31.2,
  "rhum":31.55,
  "tvoc_index":164,
  "nox_index":1,
  "pm003_count":544,
  "pm01":2,
  "pm02":2,
  "pm10":2,
  "boot":1537,
  "wdog":1
}

What are these values?

• pm003_count: PM0.3 particle count
• pm01: PM1 µg/m3
• pm02: PM2.5 µg/m3
• pm10: PM10 µg/m3
• nox_index: NOx Index (Ind41)
• tvoc_index: TVOC Index (Ind40)
• rhum: Relative Humidity %
• atmp: Temprature ºC
• rco2: CO2 PPM

Subscribing to the data

In order to view the data in something like a GUI you need to subscribe with a wildcard such as airgradient/# the default subscription for apps like MQTT Explorer shown below is just # however the permissions of the student account only allow you to view the data inside airgradient, sensors.

If you wanted just 1 sensor, you could subscribe to airgradient/sensors/(sensor) where sensor is one of the sensors listed in the sections above.