Air quality · Iowa
Air quality in Iowa
Across the 3 Iowa ZIPs with EPA county air-quality data, the median day is Good in all 3 (median AQI 37–44). 1 day across those counties reached Unhealthy or worse in 2025. This is a 2025 county annual summary, not a live reading.
Last verified 2026-09-24 · methodology
Air quality by ZIP code in Iowa
EPA's 2025 annual summary for each ZIP's county. Median AQI is the typical day; lower is cleaner.
| ZIP | Median AQI | Good days | Unhealthy or worse |
|---|---|---|---|
| 50309Des MoinesPolk County | 44 Good | 224 of 365 | 0 |
| 50266West Des Moines (IA)Polk County | 44 Good | 224 of 365 | 0 |
| 52240Iowa City (IA)Johnson County | 37 Good | 256 of 365 | 1 |
County-level figures from EPA Air Quality System (AQS), annual county summary, joined to each ZIP by county. None of them is a measurement at a specific address.
What lands here
Pages show the 2025 median AQI category (Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, Hazardous) for the ZIP's county, plus the year's max/90th-percentile AQI and day-count breakdown by category.
Source & refresh
EPA Air Quality System (AQS), annual county summary. Refreshed annual (epa aqs publication). Primary source →
Iowa top concern
Radon Zone 1, agricultural water nitrates
Iowa is one of the highest-radon states in the US — uniformly Zone 1. Agricultural runoff drives EPA SDWIS nitrate violations in small rural systems and even Des Moines Water Works. Tornadoes peak April-June.
See Iowa state page for the full state-level rollup across all 12 dimensions.
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