Idea: add Air Quality data

[nickom]

A user wrote in to suggest we add air quality data. I did some research and it looks like this may be available through the EPA here:

https://edg.epa.gov/metadata/catalog/search/resource/details.page?uuid=%7B0C82A9D9-6BBF-4E02-B82C-73C37ED78F61%7D

Title: AirNow Real Time Air Quality KML File
Dataset Group Name: Air Now
Description: A KML file with the location of all real time air quality monitors and the current conditions (air quality index).
[...]
Geographic Granularity: Coordinate pairs (latitude / longitude)