EPA AirData, 2016–2025
Air Quality Trend by County
Enter a ZIP code to see whether its county's air has gotten better, worse, or held steady over the last 10 years — no forecast, no fitted line, just the same EPA measurement compared year over year.
Showing Los Angeles County, CA
ZIP 90210 · Los Angeles County, CA
In plain terms: air quality in Los Angeles County, CA has gotten worse between 2016–2025 (90th-percentile AQI 134 to 147).
| Year | AQI90 | Category | Days measured |
|---|---|---|---|
| 2025 | 147 | Unhealthy for sensitive groups | 365 |
| 2024 | 164 | Unhealthy | 366 |
| 2023 | 147 | Unhealthy for sensitive groups | 365 |
| 2022 | 140 | Unhealthy for sensitive groups | 365 |
| 2021 | 143 | Unhealthy for sensitive groups | 365 |
| 2020 | 166 | Unhealthy | 366 |
| 2019 | 136 | Unhealthy for sensitive groups | 365 |
| 2018 | 130 | Unhealthy for sensitive groups | 365 |
| 2017 | 156 | Unhealthy | 365 |
| 2016 | 134 | Unhealthy for sensitive groups | 366 |
EPA AirData, annual AQI by county, 2016–2025. Measured at monitors in this county — county-level, not ZIP-level.
Informational only, not professional advice. This tool summarises public EPA monitoring records. It is not a health assessment or a substitute for checking current air quality at a specific address.
How this is calculated
The same 90th-percentile AQI used by the Air & Water Score tool, from EPA AirData's annual AQI by county file — one file per year, 10 years pulled (2016–2025). A county needs at least 300 measured days in a year for that year to count as complete; a year with fewer is shown but labelled partial and excluded from the trend comparison.
trend = 90th-percentile AQI in the latest complete year
− 90th-percentile AQI in the earliest complete year
move smaller than 6 AQI points → "hasn't moved much"
move of 6+ points, lower → "gotten better"
move of 6+ points, higher → "gotten worse"Deliberately not a fitted line or a projection. This site never publishes a modelled estimate — a regression line is already a model, even a simple one — so the comparison here is the plainest one that stays inside that rule: the earliest complete year on file against the latest, with the full year-by-year series printed alongside it so you can see what happened in between.
Matching a ZIP code to the data
AirData is published by county, not ZIP code, so a ZIP is mapped to the county holding the largest share of its land area — the same match the anchor tool uses. That county is named on the result.
Coverage, stated plainly
- Only the roughly half of US counties with an EPA air monitor get a trend at all — the same coverage gap as every other air tool on this site.
- A county whose monitor is newer than 2016, or that has fewer than two complete years in the window, has no trend — shown as such rather than guessed at.
Sources
- EPA AirData — annual AQI by county (2016–2025)
- US Census Bureau — 2020 ZCTA to county relationship file
Last reviewed: September 2026 · Data in use: AirData 2016–2025 · Dataset built 2026-09-02
Frequently asked questions
Why does my ZIP code have no trend?
Because there is no EPA air quality monitor in your county, or the monitor hasn't reported enough complete years yet. Monitors cover about half of US counties — the same coverage gap as the Air & Water Score tool — and a trend additionally needs at least two years with 300+ measured days to compare.
How is the trend calculated?
We compare the 90th-percentile AQI in the earliest complete year on file against the latest complete year — nothing fitted or forecast. A move smaller than 6 AQI points is called flat rather than a direction, since that's inside the year-to-year noise a monitor network normally shows.
Why not show a trend line or a forecast?
A fitted line or a projection is a model, and this site publishes only measured EPA records, never a modelled estimate. The plain first-year-vs-last-year comparison is the most defensible number we can show without crossing that line — the full year-by-year series is printed below it so you can judge the pattern yourself.
Does a 'flat' or 'improved' county mean every year in between was the same?
No. The two endpoint years can hide a lot of movement in between — a county can spike badly in one wildfire-smoke year and still show as flat or improved comparing its first and last complete years. Read the full year-by-year table below the headline before drawing a conclusion about any single year.
Related tools
Enter a ZIP code and get one score for the air and one for the drinking water, each traced to an EPA record.
Open tool →Cleanest Air by StateEvery state ranked by how clean its measured air is, with the monitored counties behind each rank.
Open tool →Compare Two ZIP CodesPut two ZIP codes side by side and see which has the better air, the better water, and by how much.
Open tool →Best & Worst Counties for Air and Water QualityThe 100 best and 100 worst US counties for air and water together, with a ZIP code to try for each.
Open tool →