About AirHistory
Clean air, measured at your doorstep.
What we do
AirHistory tracks decades of U.S. air-quality monitor readings so residents, journalists, and researchers can see how clean the air actually is where they live, work, and send their kids to school.
We focus on U.S. air quality and pollution monitoring. Every page on airhistory.org is built from the EPA Air Quality System (AQS), cited and linkable so readers can trace any number back to its source.
Who this is for
AirHistory is built for parents, public-health researchers, local reporters, and anyone with asthma or allergies who wants an honest look at their air.
Why this exists
Public data on U.S. air quality and pollution monitoring is technically free, but practically locked behind file formats, acronyms, and paywalled dashboards. AirHistoryexists to close that gap: take the raw federal and public-sector data, and turn it into pages a normal person can read in thirty seconds.
How we work
- Primary source only. We pull from the EPA Air Quality System (AQS) and cite the exact dataset and version on every page.
- No invented numbers. If a figure is not in the underlying public data, it does not appear on airhistory.org. We never generate synthetic statistics to fill gaps.
- Methodology, in plain English. We aggregate EPA AQS monitor-by-monitor readings into annual averages for ozone, PM2.5, PM10, NO2, SO2, CO, and lead, then compute county- and state-level trends over the full reporting history. Pages surface both the raw EPA AQI and plain-English day counts in each AQI bucket so readers can skip the jargon.
- Refreshed on a schedule. Refreshed from the EPA AQS API roughly every four months, tracking the cadence at which EPA closes out each reporting quarter.
- Corrections welcome. Readers flag issues all the time. When the source fixes a record, AirHistory follows.
Known limitations
AQS data lags real-world readings by several months because states run quality checks before submitting monitor data to EPA, and not every county has a monitor — rural counties are often represented by the closest upwind monitor rather than a local one.
Independence
AirHistory is an independent publication. We are not funded, owned, or directed by any of the agencies, companies, or organizations that appear in our data. Hosting is paid for by advertising — see our Privacy Policy for details — and we do not take paid placements, sponsored rankings, or "remove-my-entry" fees.
History
AirHistory launched in 2025 as part of a small portfolio of independent public-data sites. It has been maintained and updated continuously since.
Contact
Tips, corrections, data-partnership questions, and press inquiries: [email protected]. More options on our contact page.