The Air Resources Laboratory (which runs the READY site through which you asked your question) is distributed across the nation, with Divisions as far away as Las Vegas and Idaho Falls. We all look at air quality, but only as much as our research programs require. In the Silver Spring Division, we do indeed concentrate on the Chesapeake Bay -- because it is the closest aquatic system that is endangered. Our North Carolina division focuses on the Neuse River. Our group in Tennessee concentrates on Tampa Bay. And so on.
For routine air quality data, we all rely on the Environmental Protection Agency (EPA). If you are interested, look for the "AIRNOW" web site. http://www.epa.gov/airnow/
We hope this helps.
Bruce Hicks
Director, ARL