Methodology & Governance
How the Air Quality Intelligence Works
Source foundation
EPA evidence + NDS geography.
The publication layer is built from the certified Relationship Intelligence database, with EPA annual county AQI and PM2.5 monitor evidence federated from the Environmental EPA Air Quality US backbone.
County evidence
Annual EPA AQI evidence is county-derived.
ZIP presentation
The Relationship backbone supplies authoritative county FIPS geography for ZIP presentation.
NDS rankings
Scores and grades are analytical context, not EPA regulatory classifications or health advisories.
ZIPs sharing a county intentionally inherit the same county evidence and rank. NDS does not create fake within-county ZIP rankings.