I’ve started a new project recently to build an air quality monitoring station. This really came about after me being curious as to how bad the air quality was during my daily commute into London. There are parts of that commute where I can literally taste the car fumes and so was curious exactly how bad it really was. Also, I watched a video recently about how high CO2 levels affect your cognitive performance and that got me very curious as to what the levels of CO2 were, both at home and in my work office. So, I decided to build a portable air quality monitoring station to sense and record the levels of both particulates, CO and CO2, with more sensors to be added at a later date.
So, the micro-controller I am using for this project is a NodeMCU Amica which is an ESP8266 based device. The advantage of this is a fast processor (up to 160MHz) lots of memory (4Mb) and plenty of pins broken out to add peripherals to. I am currently using a small ILI9341 based TFT colour display and have an Sensirion SPS30 particulate sensor attached to display the size and concentration of particles. I also have an MQ9 Carbon Monoxide sensor and a MH-Z19 Carbon Dioxide sensor. Both have yet to be attached.
In the image above you can see the current output on the display. Top left and right I am showing the number of particles of sizes 2.5 microns or smaller and 10 microns or smaller respectively per metre cubed. The bottom shows the concentration of these sized particles per cm cubed. I am using a NEO-6M GPS module to provide the data and time for logging purposes. I will also be using this to log the location for when the device is being used during travel or in different locations.
The code currently keeps a running average of the totals per minute, per hour and per 24 hours. These will be used to display the Air Quality Index (according to Defra).
Later additions to this project will be to add the CO and CO2 sensors, to record the data onto an SD Card and to also transmit the data to somewhere it can be viewed online. I may use the Adafruit MQTT service for this. I have not decided fully yet. I may also add in further sensors at a later date to make it into a full environmental monitoring station and couple the data from this device with that being received from my external weather station.
If you are interested in seeing this device in action or would like to learn how to build your own, then pop along to a Medway Makers meetup to see it for yourself. Further updates to this project will be posted as further progress is made.