Great! The pin numbers are arbitrary. 20 and 21 match the next version of SkyWeather which supports this device.
We have our new weather station prototype in the basement of my home and we had a pizza burning incident upstairs in the kitchen and boy did the air quality sensor pick that up! You can see the filters on the furnace start to take it out all the way back down to 4 by morning. Here is our Blynk app for SkyWeather showing just that.
Great example! We didn't have a "pizza incident", but when I moved the sensor to another part of the house the AQI began to climb so I turned on the air handler fan and the value dropped back to 4. Proves the filter does help air quality quite a bit
The graph is interesting -- makes me start thinking about a complete new weather station as my original Davis station is now over 15 years old and nearing end of life.