Oregon · County air quality · 2025
Crook County, Oregon
Median AQI 28 (Good). 72.9% of monitored days rated Good, direct from EPA Air Quality System stations.
- 28
- Median AQI
- 72.9%
- Good-air days
- 0
- Unhealthy days
- 38%
- Cleaner than US counties
Crook County's 2025 annual median AQI is 28 (Good), with 72.9% Good days
According to the U.S. EPA Air Quality System, Crook County, Oregon posted a 2025 median AQI of 28 (Good) across 365 monitored days, with 72.9% rated Good and 0 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Crook County's 72.9% Good-day share places it cleaner than 38% of US counties in 2025.
- Closest median-AQI peer
- Cass County (82.7% Good, median AQI 28) is the closest nationwide median-AQI peer to Crook County.
- 2020–2025 trend
- Crook County's floor-qualifying Good-day share is stable from 2020 to 2025 (72.7% → 72.9%).
- Median AQI
- Median AQI: 28
According to the 2025 EPA AQS county release on PlainAirData, Crook County, Oregon ranks #81 of 951 by median AQI (28) and #582 by good-day share (72.9%). Ponce County, Puerto Rico is #1 of 951 by median AQI (3, 91.4% Good days) at good-day-share #159 ≠ largest of 7 at 100.0% Good days #1 by good-day share (100.0%, median AQI 9) at median-AQI #7.
Annual release change
What changed in the 2025 EPA annual release
- Crook County's Good-day share fell from 77.0% to 72.9% between the 2024 and 2025 EPA annual releases, a change of -4.2 percentage points.
- Crook County's Unhealthy-category days fell from 3 to 0 between the 2024 and 2025 EPA annual releases, a change of -3 days.
- Crook County's peak single-day AQI fell from 173 to 144 between the 2024 and 2025 EPA annual releases, a change of -29 points.
- Crook County's median AQI rose from 24 to 28 between the 2024 and 2025 EPA annual releases, a change of +4 points.
Data updated August 2026
- Good · 266 d · 72.9%
- Moderate · 97 d · 26.6%
- USG · 2 d · 0.5%
How did Crook County's air break down in 2025?
Across 365 monitored days, 266 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 144 (USG).
EPA AQS →Share of monitored days at AQI 0-50 (Good band).
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
Where Crook County sits nationally
COUNT-derived placement among 951 US counties with at least 100 monitored days in 2025. Crook County's Good-day share is 72.9% - cleaner than 38% of that comparison set.
Crook County Good-day share vs. every US county
Share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release
72.9% 38th percentile higher than 38% of 951 US counties
Each bar is a band; taller bars hold more US counties. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source U.S. Environmental Protection Agency, Air Quality System (AQS) · 2025
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Crook County.
- PM2.5 · 365 days · 100.0%
2024 daily-monitor rhythm in Crook County
Month-by-month median AQI from EPA day-level county monitors (366 reported days in 2024). Dec posted the highest typical readings (median AQI 49, peak 84); May was cleanest at median 12. Summer months (Jun–Aug) averaged median AQI 33 vs 40 in Dec–Feb. 3 days crossed Unhealthy (AQI >150) at least once that year.
Five-year seasonal record
EPA day-level county files · 2020–20241,820 daily readings show a recurring local pattern: Aug has the highest matched-month median AQI (46), while May is lowest (15). Each cell is that month’s median daily AQI, not a current-air forecast.
Lower AQI is better. The colors summarize EPA AQI bands; gaps mean the county had no day-level record for that month.
Health Impact Assessment
Crook County's air quality is rated Moderate based on 72.9% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 72.9% of monitored days in 2025, with a median AQI of 28. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 365 of 365 monitored days.
5-Year Air Quality Trend
Air quality is stable in Crook County. Highest Good-day share: 2022 (80.2%, 288 of 359 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 261 | 97 | 0 | 1 | 28 | 1033 |
| 2021 | 281 | 75 | 6 | 3 | 28 | 190 |
| 2022 | 288 | 69 | 2 | 0 | 24 | 128 |
| 2023 | 267 | 86 | 6 | 6 | 33 | 171 |
| 2024 | 282 | 76 | 5 | 3 | 24 | 173 |
| 2025 | 266 | 97 | 2 | 0 | 28 | 144 |
How does Crook County compare?
How Crook County compares
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Crook County, Oregon · 2020–2025
Download this county's annual AQI row as CSV , with the same EPA fields and denominator shown on this page.
Every figure on PlainAirData is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.