EnviroNearby

McLennan County, Texas air quality history

Daily Air Quality Index summaries from EPA monitors in McLennan, Texas, 2000–2025.

47%
Good days in 2025
51
Median daily AQI, 2025
3
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for McLennan, Texas on 365 days. 170 of those days (47%) were in the Good range, and the median daily AQI was 51. That median is higher than the typical monitored county in Texas (median 43.5 across 44 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 257 days. Across the years with fuller monitoring, the share of Good days fell: an average of 49% in 2001–2007 versus 42% in 2023–2025.

Years with fewer than 120 monitored days (2000, 2003) 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%2000: Good 34 of 75 days2000: Moderate 41 of 75 days20002001: Good 66 of 125 days2001: Moderate 58 of 125 days2001: Unhealthy for Sensitive Groups 1 of 125 days2002: Good 72 of 140 days2002: Moderate 67 of 140 days2002: Unhealthy for Sensitive Groups 1 of 140 days20022003: Good 16 of 30 days2003: Moderate 14 of 30 days2007: Good 107 of 256 days2007: Moderate 141 of 256 days2007: Unhealthy for Sensitive Groups 8 of 256 days20072008: Good 192 of 363 days2008: Moderate 166 of 363 days2008: Unhealthy for Sensitive Groups 5 of 363 days2009: Good 199 of 365 days2009: Moderate 161 of 365 days2009: Unhealthy for Sensitive Groups 5 of 365 days20092010: Good 252 of 365 days2010: Moderate 111 of 365 days2010: Unhealthy for Sensitive Groups 2 of 365 days2011: Good 195 of 365 days2011: Moderate 151 of 365 days2011: Unhealthy for Sensitive Groups 19 of 365 days20112012: Good 257 of 366 days2012: Moderate 105 of 366 days2012: Unhealthy for Sensitive Groups 3 of 366 days2012: Unhealthy 1 of 366 days2013: Good 233 of 361 days2013: Moderate 124 of 361 days2013: Unhealthy for Sensitive Groups 4 of 361 days20132014: Good 236 of 365 days2014: Moderate 128 of 365 days2014: Unhealthy for Sensitive Groups 1 of 365 days2015: Good 250 of 365 days2015: Moderate 112 of 365 days2015: Unhealthy for Sensitive Groups 3 of 365 days20152016: Good 327 of 366 days2016: Moderate 39 of 366 days2017: Good 166 of 193 days2017: Moderate 26 of 193 days2017: Unhealthy for Sensitive Groups 1 of 193 days20172018: Good 248 of 312 days2018: Moderate 64 of 312 days2019: Good 313 of 365 days2019: Moderate 52 of 365 days20192020: Good 294 of 366 days2020: Moderate 72 of 366 days2021: Good 280 of 364 days2021: Moderate 84 of 364 days20212022: Good 209 of 364 days2022: Moderate 155 of 364 days2023: Good 169 of 365 days2023: Moderate 188 of 365 days2023: Unhealthy for Sensitive Groups 8 of 365 days20232024: Good 126 of 365 days2024: Moderate 234 of 365 days2024: Unhealthy for Sensitive Groups 5 of 365 days2025: Good 170 of 365 days2025: Moderate 192 of 365 days2025: Unhealthy for Sensitive Groups 3 of 365 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 year0501002000: 90th percentile AQI 652001: 90th percentile AQI 672002: 90th percentile AQI 652003: 90th percentile AQI 782007: 90th percentile AQI 732008: 90th percentile AQI 682009: 90th percentile AQI 712010: 90th percentile AQI 612011: 90th percentile AQI 842012: 90th percentile AQI 672013: 90th percentile AQI 672014: 90th percentile AQI 642015: 90th percentile AQI 642016: 90th percentile AQI 512017: 90th percentile AQI 542018: 90th percentile AQI 582019: 90th percentile AQI 542020: 90th percentile AQI 542021: 90th percentile AQI 592022: 90th percentile AQI 642023: 90th percentile AQI 752024: 90th percentile AQI 732025: 90th percentile AQI 652000: Median AQI 522001: Median AQI 472002: Median AQI 492003: Median AQI 492007: Median AQI 532008: Median AQI 492009: Median AQI 482010: Median AQI 442011: Median AQI 492012: Median AQI 432013: Median AQI 452014: Median AQI 442015: Median AQI 422016: Median AQI 372017: Median AQI 392018: Median AQI 382019: Median AQI 392020: Median AQI 392021: Median AQI 392022: Median AQI 482023: Median AQI 522024: Median AQI 532025: Median AQI 51200020022007200920112013201520172019202120232025
  • 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
Fine particles (PM2.5)25770%
Ozone10428%
Carbon monoxide (CO)41%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536517019230005165142PM2.5
202436512623450005373133PM2.5
202336516918880005275129PM2.5
202236420915500004864100PM2.5
20213642808400003959100Ozone
2020366294720000395497Ozone
2019365313520000395487Ozone
2018312248640000385898Ozone
20171931662610003954112Ozone
2016366327390000375176Ozone
201536525011230004264115Ozone
201436523612810004464105PM2.5
201336123312440004567115Ozone
201236625710531004367154Ozone
2011365195151190004984147Ozone
201036525211120004461115PM2.5
200936519916150004871143PM2.5
200836319216650004968133PM2.5
200725610714180005373122PM2.5
20033016140000497894PM2.5
2002140726710004965127PM2.5
2001125665810004767104PM2.5
20007534410000526585PM2.5

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 2000–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem