Texas · County air quality · 2025
Ellis County, Texas
Median AQI 35 (Good). 89.2% of monitored days rated Good, direct from EPA Air Quality System stations.
- 35
- Median AQI
- 89.2%
- Good-air days
- 0
- Unhealthy days
- 78%
- Cleaner than US counties
Ellis County's 2025 annual median AQI is 35 (Good), with 89.2% Good days
According to the U.S. EPA Air Quality System, Ellis County, Texas posted a 2025 median AQI of 35 (Good) across 362 monitored days, with 89.2% 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
- Ellis County's 89.2% Good-day share places it cleaner than 78% of US counties in 2025.
- Closest median-AQI peer
- Atascosa County (76.0% Good, median AQI 35) is the closest nationwide median-AQI peer to Ellis County.
- 2020–2025 trend
- Ellis County's floor-qualifying Good-day share is improving from 2020 to 2025 (65.3% → 89.2%).
- Median AQI
- Median AQI: 35
According to the 2025 EPA AQS county release on PlainAirData, Ellis County, Texas ranks #191 of 951 by median AQI (35) and #205 by good-day share (89.2%). 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.
Data updated August 2026
- Good · 323 d · 89.2%
- Moderate · 39 d · 10.8%
How did Ellis County's air break down in 2025?
Across 362 monitored days, 323 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 93 (Moderate).
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 Ellis County sits nationally
COUNT-derived placement among 951 US counties with at least 100 monitored days in 2025. Ellis County's Good-day share is 89.2% - cleaner than 78% of that comparison set.
Ellis County Good-day share vs. every US county
Share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release
89.2% Cleaner than 78% higher than 78% 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 Ellis County.
- Ozone · 358 days · 98.9%
- NO₂ · 4 days · 1.1%
2024 daily-monitor rhythm in Ellis County
Month-by-month median AQI from EPA day-level county monitors (362 reported days in 2024). Oct posted the highest typical readings (median AQI 49, peak 90); Dec was cleanest at median 28. Summer months (Jun–Aug) averaged median AQI 37 vs 30 in Dec–Feb.
Five-year seasonal record
EPA day-level county files · 2020–20241,803 daily readings show a recurring local pattern: Aug has the highest matched-month median AQI (48), while Dec is lowest (31). 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
Ellis County's air quality is rated Good based on 89.2% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 89.2% of monitored days in 2025, with a median AQI of 35. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 358 of 362 monitored days.
5-Year Air Quality Trend
Air quality is improving in Ellis County. Highest Good-day share: 2025 (89.2%, 323 of 362 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 239 | 126 | 1 | 0 | 45 | 125 |
| 2021 | 262 | 100 | 1 | 0 | 43 | 105 |
| 2022 | 311 | 53 | 0 | 0 | 38 | 97 |
| 2023 | 286 | 60 | 2 | 0 | 36 | 112 |
| 2024 | 323 | 38 | 1 | 0 | 36 | 101 |
| 2025 | 323 | 39 | 0 | 0 | 35 | 93 |
How does Ellis County compare?
How Ellis 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 Ellis County, Texas · 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.