Just to mention to people, I develop a FOSS MacOS toolbar app that, among other functions, shows SmartCitizen using the API - all the different instantaneous parameters, and also looks at historical parameters too to get some context. I developed it mainly when my child was diagnosed with asthma, and I needed an app to flash an alert if the air quality disimproved.
Might be of use to some people - check it out at: Miasma - Local Air Quality on the App Store & happy to receive feedback.
Darragh