EnviroNearby

Ellis County, Texas air quality history

Daily Air Quality Index summaries from EPA monitors in Ellis, Texas, 1991–2025.

89%
Good days in 2025
35
Median daily AQI, 2025
0
Days above 100 in 2025
362
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Ellis, Texas on 362 days. 323 of those days (89%) were in the Good range, and the median daily AQI was 35. That median is lower than the typical monitored county in Texas (median 43.5 across 44 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 358 days. Across the years with fuller monitoring, the share of Good days rose: an average of 65% in 1991–1997 versus 87% in 2023–2025.

Years with fewer than 120 monitored days (1992, 1993, 1994, 1995) are shown in the table but left out of comparisons and trend statements.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Share of monitored days in each AQI category, by year0%25%50%75%100%1991: Good 177 of 257 days1991: Moderate 52 of 257 days1991: Unhealthy for Sensitive Groups 28 of 257 days19911992: Good 60 of 64 days1992: Moderate 4 of 64 days1993: Good 57 of 61 days1993: Moderate 4 of 61 days1994: Good 58 of 60 days1994: Moderate 2 of 60 days1995: Good 59 of 61 days1995: Moderate 2 of 61 days1996: Good 71 of 123 days1996: Moderate 42 of 123 days1996: Unhealthy for Sensitive Groups 9 of 123 days1996: Unhealthy 1 of 123 days19961997: Good 111 of 160 days1997: Moderate 34 of 160 days1997: Unhealthy for Sensitive Groups 13 of 160 days1997: Unhealthy 2 of 160 days1998: Good 229 of 353 days1998: Moderate 85 of 353 days1998: Unhealthy for Sensitive Groups 28 of 353 days1998: Unhealthy 9 of 353 days1998: Very Unhealthy 2 of 353 days1999: Good 224 of 347 days1999: Moderate 72 of 347 days1999: Unhealthy for Sensitive Groups 32 of 347 days1999: Unhealthy 18 of 347 days1999: Very Unhealthy 1 of 347 days2000: Good 247 of 364 days2000: Moderate 67 of 364 days2000: Unhealthy for Sensitive Groups 36 of 364 days2000: Unhealthy 13 of 364 days2000: Very Unhealthy 1 of 364 days2001: Good 307 of 365 days2001: Moderate 52 of 365 days2001: Unhealthy for Sensitive Groups 6 of 365 days20012002: Good 273 of 364 days2002: Moderate 58 of 364 days2002: Unhealthy for Sensitive Groups 24 of 364 days2002: Unhealthy 9 of 364 days2003: Good 260 of 365 days2003: Moderate 85 of 365 days2003: Unhealthy for Sensitive Groups 15 of 365 days2003: Unhealthy 5 of 365 days2004: Good 269 of 366 days2004: Moderate 81 of 366 days2004: Unhealthy for Sensitive Groups 11 of 366 days2004: Unhealthy 4 of 366 days2004: Very Unhealthy 1 of 366 days2005: Good 105 of 365 days2005: Moderate 234 of 365 days2005: Unhealthy for Sensitive Groups 25 of 365 days2005: Unhealthy 1 of 365 days2006: Good 137 of 365 days2006: Moderate 205 of 365 days2006: Unhealthy for Sensitive Groups 22 of 365 days2006: Unhealthy 1 of 365 days20062007: Good 156 of 365 days2007: Moderate 202 of 365 days2007: Unhealthy for Sensitive Groups 6 of 365 days2007: Unhealthy 1 of 365 days2008: Good 143 of 366 days2008: Moderate 210 of 366 days2008: Unhealthy for Sensitive Groups 13 of 366 days2009: Good 161 of 365 days2009: Moderate 192 of 365 days2009: Unhealthy for Sensitive Groups 12 of 365 days2010: Good 193 of 365 days2010: Moderate 167 of 365 days2010: Unhealthy for Sensitive Groups 5 of 365 days2011: Good 172 of 365 days2011: Moderate 178 of 365 days2011: Unhealthy for Sensitive Groups 14 of 365 days2011: Unhealthy 1 of 365 days20112012: Good 167 of 366 days2012: Moderate 188 of 366 days2012: Unhealthy for Sensitive Groups 9 of 366 days2012: Unhealthy 1 of 366 days2012: Very Unhealthy 1 of 366 days2013: Good 187 of 365 days2013: Moderate 170 of 365 days2013: Unhealthy for Sensitive Groups 8 of 365 days2014: Good 193 of 365 days2014: Moderate 172 of 365 days2015: Good 224 of 365 days2015: Moderate 138 of 365 days2015: Unhealthy for Sensitive Groups 3 of 365 days2016: Good 234 of 366 days2016: Moderate 132 of 366 days20162017: Good 183 of 365 days2017: Moderate 179 of 365 days2017: Unhealthy for Sensitive Groups 3 of 365 days2018: Good 229 of 365 days2018: Moderate 128 of 365 days2018: Unhealthy for Sensitive Groups 8 of 365 days2019: Good 250 of 365 days2019: Moderate 115 of 365 days2020: Good 239 of 366 days2020: Moderate 126 of 366 days2020: Unhealthy for Sensitive Groups 1 of 366 days2021: Good 262 of 363 days2021: Moderate 100 of 363 days2021: Unhealthy for Sensitive Groups 1 of 363 days20212022: Good 311 of 364 days2022: Moderate 53 of 364 days2023: Good 286 of 348 days2023: Moderate 60 of 348 days2023: Unhealthy for Sensitive Groups 2 of 348 days2024: Good 323 of 362 days2024: Moderate 38 of 362 days2024: Unhealthy for Sensitive Groups 1 of 362 days2025: Good 323 of 362 days2025: Moderate 39 of 362 days2025
  • Good
  • Moderate
  • Unhealthy for Sensitive Groups
  • Unhealthy
  • Very Unhealthy
  • Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median and 90th-percentile daily AQI, by year0501001501991: 90th percentile AQI 1011992: 90th percentile AQI 461993: 90th percentile AQI 401994: 90th percentile AQI 341995: 90th percentile AQI 391996: 90th percentile AQI 971997: 90th percentile AQI 871998: 90th percentile AQI 1051999: 90th percentile AQI 1262000: 90th percentile AQI 1192001: 90th percentile AQI 642002: 90th percentile AQI 1002003: 90th percentile AQI 842004: 90th percentile AQI 742005: 90th percentile AQI 902006: 90th percentile AQI 872007: 90th percentile AQI 702008: 90th percentile AQI 772009: 90th percentile AQI 802010: 90th percentile AQI 662011: 90th percentile AQI 842012: 90th percentile AQI 742013: 90th percentile AQI 772014: 90th percentile AQI 642015: 90th percentile AQI 662016: 90th percentile AQI 592017: 90th percentile AQI 632018: 90th percentile AQI 672019: 90th percentile AQI 582020: 90th percentile AQI 612021: 90th percentile AQI 602022: 90th percentile AQI 542023: 90th percentile AQI 612024: 90th percentile AQI 512025: 90th percentile AQI 511991: Median AQI 441992: Median AQI 231993: Median AQI 191994: Median AQI 231995: Median AQI 211996: Median AQI 461997: Median AQI 391998: Median AQI 431999: Median AQI 432000: Median AQI 422001: Median AQI 372002: Median AQI 382003: Median AQI 402004: Median AQI 372005: Median AQI 552006: Median AQI 542007: Median AQI 522008: Median AQI 532009: Median AQI 522010: Median AQI 502011: Median AQI 522012: Median AQI 522013: Median AQI 502014: Median AQI 482015: Median AQI 462016: Median AQI 462017: Median AQI 502018: Median AQI 452019: Median AQI 442020: Median AQI 452021: Median AQI 432022: Median AQI 382023: Median AQI 362024: Median AQI 362025: Median AQI 3519911996200120062011201620212025
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2025

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

PollutantDays as main pollutantShare of monitored days
Ozone35899%
Nitrogen dioxide (NO₂)41%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025362323390000355193Ozone
20243623233810003651101Ozone
20233482866020003661112Ozone
2022364311530000385497Ozone
202136326210010004360105Ozone
202036623912610004561125PM2.5
20193652501150000445897Ozone
201836522912880004567120PM2.5
201736518317930005063122PM2.5
201636623413200004659100PM2.5
201536522413830004666136PM2.5
20143651931720000486497PM2.5
201336518717080005077150PM2.5
201236616718891105274201PM2.5
2011365172178141005284174PM2.5
201036519316750005066115PM2.5
2009365161192120005280129PM2.5
2008366143210130005377138PM2.5
200736515620261005270172PM2.5
2006365137205221005487182PM2.5
2005365105234251005590172PM2.5
200436626981114103774203Ozone
200336526085155004084159Ozone
2002364273582490038100185Ozone
20013653075260003764126Ozone
20003642476736131042119203Ozone
19993472247232181043126203Ozone
1998353229852892043105216Ozone
199716011134132003987172Ozone
1996123714291004697159Ozone
1995615920000213965PM10
1994605820000233465PM10
1993615740000194060PM10
1992646040000234673PM10
1991257177522800044101150Ozone

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

Counties in Texas with a similar median AQI in 2025

All monitored counties in Texas

Source: U.S. EPA AirData, “Annual AQI by County” files for 1991–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem