We are trying to create a network of air-pollution sensors in Greece that also sends data to sensor.community. We have built the sensors, and now it’s time to create a visual-representation project. This way, you can have the sensor, for example, on your balcony, but still see exactly what is happening inside your living room.
We used a Wemos D1 Mini and a WS2812B LED Ring (7 LEDs)
feel free to use.. and excuse us, this is our first public release..
the main color values dependent to the P2 value are
5 light blue
15 light green
25 yellow
4 orange
55 red <breathing 3sec cycle above 50>
60 and more purple <breathing 1sec cycle above 60>
all between values are gradient
I think it’s a great idea to work on visualization of air quality. Visualisation with a color gives an immediate non-technical indication of what is going on.
With respect to the colours, there is so much choice of what concentration you associate with what colour. One of the ranges used in the netherlands avoids the use of the color green, because that would suggest there is a good or ‘harmless’ level of PM: Luchtmeetnet.nl
The WHO has its own (slightly more strict I think) than our national ranges.
there were a couple of similar projects, but for different hardware.
i couldn’t make them work, so i started a new one from scratch.
we intend to make a full product, in order to sell it and finance our sensor network.
but the code is always open sourced.. 
