Here is a very relevant article about a group similar to our own. The article makes explains clearly how low cost air quality devices can be powerful tools; why the data can be used (with care) and how citizens can get involved. Recommended reading.
Shame they don’t identify the PM sensor in the box.
It has two sensor (laser) and does pm1, 2.5 and 10
I wonder if this part of their JSON to thingspeak gives a clue
“Type”:“TYPE”, // Sensor type (PMS5003, PMS1003, BME280 etc)
Definitely pms devices but not 7003 mine have intake/ outlet on the side.
Also, PMS7003 does all three PM readings so should only need one.
Those are PMS5003 for sure. Rob M has one and it is just like the photo. The PMS7003 is a similar device - smaller and more software features but the same interface.
It says they calibrate them against a ‘smoke chamber’, if they do all or just sample a selection in a batch. I doubt we’ll know.