Fun challenge! I chose to make it a little more dynamic by building a tree that can be used to choose your city (I attached the workflow I used to build the tree as well). Noticed after testing for a few different cities that I needed to group by Site # since there are some cities that contained more than one Site (which was creating unusually high AQI values for the month by summarizing them together across sites). So I split out the output report into a separate grid per Site (based on city selected in the tree). Used Phoenix, Arizona as my sample city selection, largely because it's been 20 degrees here this week, so you know, wishful thinking. Plus the air quality looks pretty good!
Started along the same path as @patrick_digan, grabbing the table from the EPA website. But ultimately decided to copy the results into a text table. Used a dynamic replace tool instead of a nested IF to assign the category. Transpose, summarize, crosstab, and report!
Created an app that allows the user to choose which city they'd like to see, and outputs the result. Tried the tree tool for the first time. Creating the table was a great exercise with using the Tile tool.
I'd love to make this dynamic and have the data pulled directly from the web, for the most current data. Any suggestions @ChristineB?