Changelog
A dated record of data refreshes, corrections, and methodology changes on PlainAirData. We list only real, verifiable changes. See our corrections process if a figure looks wrong, or methodology for how the EPA AQS pipeline works. Year-over-year AQI movers live on /changes, a separate data page.
Public /corrections alias and identity CiteThis blocks
Added a /corrections redirect to the editorial corrections process, a public /changelog of corroborated changes, and Cite this page blocks on identity and legal pages so readers have a stable citation string and a clear path to report data issues.
Honest per-page sitemap lastmod
Static, research, and rankings sitemap entries now stamp lastmod from git or data vintage per route instead of a single portal-wide fingerprint (commit 8063fca).
Answer capsules on index answer surfaces
Shared DataInsightSummary and home/rankings/guides SynthesisBand now carry a machine-legible data-answer-capsule so AI and snippet extractors can quote a stable lead answer (commits 55b2ad4, 30600f5).
Monitoring coverage numerator matches full state population
Home and /states coverage bars now count all 53 monitored jurisdictions (was a display-slice numerator mislabeled as counties) so the coverage claim matches the full tile population (commit 9cae2ce).
Non-blocking font load for Core Web Vitals
Base font loading switched to preload with display=optional so first paint is not blocked on Google Fonts stylesheet swap (commit 06196a7).
Download the EPA AQS annual county AQI extract cited on this page: annual-aqi-by-county.csv or the JSON distribution (public domain / CC0). Method notes live on /methodology and /data.