Median AQI
31
Good
Kansas · County air quality · 2025
Chase County, Kansas
Limited EPA sample: 99 monitored days, below the 100-day floor for a full-year verdict. The figures below describe only those reported days.
- 31
- Sample median AQI
- 82.8%
- Good in sample
- 0
- Unhealthy in sample
- 99
- 100-day comparison floor
Chase County has only 99 EPA-monitored days in 2025, below the 100-day annual floor
According to the U.S. EPA Air Quality System, Chase County, Kansas reported 99 monitored days in 2025. That sample is too thin for a full-year air-quality grade or peer ranking. Use the figures only as the reported-day record, and check AirNow for current conditions.
Data source EPA Air Quality System (AQS)
- Monitored days
- Chase County reported 99 monitored days in 2025, below the 100-day floor: sample-only, not a full-year peer rank.
- Sample median AQI
- Sample median AQI: 31
- Annual floor
- Annual floor: 100
The verdict
EPA monitors reported 99 days for Chase County in 2025, below our 100-day floor for an annual verdict or national comparison. The median AQI of 31 and 82.8% Good-day share describe only those reported days, not the full year.
- 31
- sample median AQI · Good
- 82.8%
- reported days rated Good
- 99 days
- below 100-day floor
No full-year or health conclusion is drawn from this limited reporting window. For current conditions, check EPA AirNow.
Annual release change
What changed in the 2024 EPA annual release
- Chase County's Good-day share rose from 83.8% to 86.9% between the 2023 and 2024 EPA annual releases, a change of +3.1 percentage points.
- Chase County's peak single-day AQI rose from 79 to 94 between the 2023 and 2024 EPA annual releases, a change of +15 points.
Data updated August 2026
- Good · 82 d · 82.8%
- Moderate · 17 d · 17.2%
How did Chase County's reported sample break down in 2025?
Across 99 monitored days, 82 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 95 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 99 days monitored. Median AQI: 31 (Good).
Limited sample: Chase County, Kansas. EPA monitors reported 99 days in 2025, short of the 100-day minimum used here for annual verdicts, health grades, rankings, and peer comparisons. Within those reported days, the median was AQI 31, 82 days (83%) were Good, 17 were Moderate, and 0 were Unhealthy for Sensitive Groups. Those figures are observations from the sample, not estimates for unreported days.
The sample's pollutant mix was PM2.5 (99 days). A gap in reporting can miss seasonal ozone, smoke, or inversion events, so a clean or unhealthy-looking short window must not be generalized to the year. This page therefore withholds a county health grade and national placement. Use the floor-qualifying years in the trend table for historical context and EPA AirNow for current conditions.
Air Quality Summary
Good Days
82.8%
82 of 99 monitored days
7.8pp vs 75% target
Max AQI Recorded
95
Moderate
Coverage Status
Limited sample
99 of 100 required days
AQI Day Breakdown (2025)
Distribution of 99 monitored days across EPA AQI categories.
Good
82
83%
Moderate
17
17%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Chase County.
- PM2.5 · 99 days · 100.0%
Sample Coverage and Health Context
Limited sample
Chase County has no annual health grade because only 99 days were reported, below the 100-day floor. The 82.8% Good-day share describes only that sample.
Reported days do not reveal what happened during unmonitored parts of the year, including seasonal smoke, ozone, or inversion periods. Use these values as a description of the available EPA sample only, and check AirNow.gov for current health guidance.
The dominant pollutant is PM2.5, driving AQI on 99 of 99 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Chase County. Highest Good-day share: 2022 (90.9%, 110 of 121 monitored days). The 2025 row is shown for transparency but excluded from the direction because it has fewer than 100 monitored days.
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 110 | 11 | 0 | 0 | 24 | 63 |
| 2021 | 102 | 18 | 0 | 0 | 27 | 99 |
| 2022 | 110 | 11 | 0 | 0 | 25 | 66 |
| 2023 | 98 | 19 | 0 | 0 | 29 | 79 |
| 2024 | 106 | 16 | 0 | 0 | 29 | 94 |
| 2025 | 82 | 17 | 0 | 0 | 31 | 95 |
Kansas counties on the map
State neighbors are listed for navigation; Chase County's limited sample is not scored against them.
What Chase County's air means for you
Only 99 days were reported in 2025. That is too little evidence for a year-round air-quality or health conclusion.
- Treat the median AQI and Good-day share as observations from the reported sample, not as estimates for unmonitored days. How coverage works
- Use EPA AirNow for current readings and health alerts; this page contains historical annual-summary data. Current conditions
- Browse Kansas counties with fuller monitoring records before drawing a regional comparison. All of Kansas
Limited coverage: 99 EPA-monitored days in 2025, below the 100-day floor for annual claims and comparisons. No values are imputed for missing days.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Chase County, Kansas? ▼
EPA monitors reported only 99 days for Chase County in 2025, below the 100-day floor used for annual conclusions. Within that limited sample, the median AQI was 31 and 82 days were rated Good; this does not describe the full year.
What is the main pollutant in Chase County? ▼
The primary pollutant in Chase County is Fine Particles (PM2.5), which was the main AQI driver on 99 days (100% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Chase County have? ▼
Among 99 reported days in 2025, 0 reached Unhealthy or worse. Because the record is below 100 monitored days, that count cannot establish how many unhealthy days occurred across the full year.
Is the air quality in Chase County getting better or worse? ▼
Air quality in Chase County is worsening across floor-qualifying years (2020-2024); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2022 at 90.9% (110 of 121 days). Lowest qualifying Good-day share: 2023 at 83.8% (98 of 117 days).
What does AQI 31 mean for health? ▼
The median of the 99 reported days was AQI 31, in the "Good" category. The limited sample is not enough to assign the county a full-year health grade. See the AQI category guide for day-level meaning and EPA AirNow for current conditions.
How does Chase County compare to other counties in Kansas? ▼
Chase County is not placed in county comparisons because its 99-day record is below the 100-day comparison floor.
What is the 90th percentile AQI in Chase County? ▼
The 90th percentile AQI for Chase County is 54, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 95 (Moderate).
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 Chase County, Kansas · 2020–2025
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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.