I was confused by the city drop down, though. I tried entering my city and zip code and other things and then realized it is a set list of 20 cities like a map with areas one can click to explore could remove the confusion and provide a route for someone to explore data points for contextual understanding.

If someone was enjoying the buildout and wanted to build it, I could see the map details being available down to county levels, and could imagine letting AI incorporate info about local industry and regulation (or lack thereof) to see what the data shows.

Or, more focused: With the scattered coal plant shutdowns across the country over the last decade, it would be interesting to see before/after air quality reports highlighting the importance of every major emission source that is taken offline for AQ in that area (just thinking out loud, I love data stuff like this - great work!)