Unfortunately Health doesn't yet store air quality, but I spelled out how air quality scores might be designed in the article. To the user it would be something akin to Fitness apps three rings but for different aspects of air quality: Safe, Fresh, and Comfortable. Within each would be specific air quality metrics (pm2.5, pm10, co, co2, vocs, temp/humidity, etc), which would sum up into three different scores for the three aspects. These would drive recommendations to the user.

I don't have an opinion on what protocol would work best, just that it needs to be localized pretty well to match up with the localization of air quality. My hunch is UWB is a better fit for that.