Purple Air provides free air quality index (AQI) numbers on their site. They also provide a javascript widget and json data feed for each sensor.
https://www.purpleair.com/map?opt=1/i/mAQI/a10/cC0&select=20501#12/37.7776/-122.4676
Click on a sensor and select 'get this widget' for options.
Would anyone be interested in tackling this? It would be great to get the '10 minute' average number along with the matching color on the TouchBar.
I don't think I have the skills to do it before fire season is over. 
Thanks!