Median AQI
33
Good
Texas · County air quality · 2025
Ellis County, Texas
Median AQI 33 (Good). 92.9% of monitored days rated Good, direct from EPA Air Quality System stations.
- 33
- Median AQI
- 92.9%
- Good-air days
- 0
- Unhealthy days
- 83%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Ellis County's air is good on balance, cleaner than most US counties, a median AQI of 33 with 92.9% of 210 monitored days in the Good band, driven mainly by Ozone.
- 33
- median AQI · Good
- 92.9%
- days rated Good
- Ozone
- main pollutant
- 83%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 84.
Data updated July 2026
- Good · 195 d · 92.9%
- Moderate · 15 d · 7.1%
How did Ellis County's air break down in 2025?
Across 210 monitored days, 195 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 84 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 210 days monitored. Median AQI: 33 (Good).
Insights: Ellis County, Texas. EPA monitors recorded a median Air Quality Index of 33 across 210 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 195 (93%) fell in the Good band (AQI 0–50), 15 (7%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 50, while the worst single-day peak hit 84 (Moderate). Residents averaged about 27.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (206 days), NO2 (4 days). Across the 2020–2025 trend window, good days shifted by -44 and the median AQI moved -12 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 84, moderate but never Unhealthy. Nearby counties show comparable readings: Atascosa (58.0% good, AQI 45); Bell (61.3% good, AQI 47); Bexar (39.8% good, AQI 53); Bowie (57.3% good, AQI 47); Brazoria (84.8% good, AQI 33); Brazos (63.4% good, AQI 43).
Air Quality Summary
Good Days
92.9%
195 of 210 monitored days
17.9pp vs 75% target
Max AQI Recorded
84
Moderate
Health Grade
Excellent
90th-pct AQI 50
Ellis County, Good days share 92.9%
National avg
Share of monitored days at AQI 0-50 (Good band).
Ellis County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 210 monitored days across EPA AQI categories.
Good
195
93%
Moderate
15
7%
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 Ellis County.
- Ozone · 206 days · 98.1%
- NO₂ · 4 days · 1.9%
Health Impact Assessment
Excellent
Ellis County's air quality is rated Excellent based on 92.9% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 92.9% of monitored days in 2025, with a median AQI of 33. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 206 of 210 monitored days.
5-Year Air Quality Trend
Air quality is improving in Ellis County. Best year: 2024 (323 good 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 | 195 | 15 | 0 | 0 | 33 | 84 |
How does Ellis County compare?
How Ellis County compares
Good-day share better than US avg
Ellis County 92.9%
Atascosa County, Texas 58.0%
US average 76.5%
Median AQI better than US avg
Ellis County 33
Atascosa County, Texas 45
US average 38
Unhealthy days / yr about average
Ellis County 0
Atascosa County, Texas 0
US average 0
Other Counties in Texas
Air quality comparison for nearby counties in Texas.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Ellis County.
Ascension County, Louisiana
AQI 33 · 94.1% good
Athens County, Ohio
AQI 33 · 80.3% good
Brazoria County, Texas
AQI 33 · 84.8% good
Bristol City County, Virginia
AQI 33 · 78.3% good
Carter County, Oklahoma
AQI 33 · 80.9% good
Codington County, South Dakota
AQI 33 · 82.1% good
What Ellis County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 33 means for exposure. Health guidance
- See how Ellis County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Ellis County with its Texas neighbours before drawing a conclusion about the region. All of Texas
Based on 210 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in Ellis County, Texas? ▼
Ellis County has a median Air Quality Index (AQI) of 33, rated "Good." 92.9% of monitored days (195 out of 210) had good air quality in 2025.
What is the main pollutant in Ellis County? ▼
The primary pollutant in Ellis County is Ozone (O3), which was the main AQI driver on 206 days (98% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Ellis County have? ▼
In 2025, Ellis County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 84.
Is the air quality in Ellis County getting better or worse? ▼
Air quality in Ellis County is improving based on 5-year trends (2020-2025). Best year: 2024 with 323 good days. Worst year: 2025 with 195 good days.
What does AQI 33 mean for health? ▼
Ellis County's median AQI of 33 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Ellis County compare to other counties in Texas? ▼
Ellis County has 92.9% good air days. Nearby counties in Texas: Atascosa (58.0% good), Bell (61.3% good), Bexar (39.8% good), Bowie (57.3% good), Brazoria (84.8% good), Brazos (63.4% good).
What is the 90th percentile AQI in Ellis County? ▼
The 90th percentile AQI for Ellis County is 50, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 84 (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.
Every figure on PlainAir 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.