EnviroNearby

Jefferson County, Texas air quality history

Daily Air Quality Index summaries from EPA monitors in Jefferson, Texas, 1980–2025.

48%
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 Jefferson, Texas on 365 days. 175 of those days (48%) 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 220 days. Across the years with fuller monitoring, the share of Good days fell: an average of 74% in 1980–1982 versus 41% in 2023–2025.

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%1980: Good 247 of 336 days1980: Moderate 55 of 336 days1980: Unhealthy for Sensitive Groups 10 of 336 days1980: Unhealthy 16 of 336 days1980: Very Unhealthy 8 of 336 days19801981: Good 290 of 360 days1981: Moderate 32 of 360 days1981: Unhealthy for Sensitive Groups 21 of 360 days1981: Unhealthy 14 of 360 days1981: Very Unhealthy 3 of 360 days1982: Good 241 of 350 days1982: Moderate 62 of 350 days1982: Unhealthy for Sensitive Groups 32 of 350 days1982: Unhealthy 9 of 350 days1982: Very Unhealthy 6 of 350 days1983: Good 236 of 337 days1983: Moderate 54 of 337 days1983: Unhealthy for Sensitive Groups 25 of 337 days1983: Unhealthy 17 of 337 days1983: Very Unhealthy 5 of 337 days1984: Good 263 of 363 days1984: Moderate 53 of 363 days1984: Unhealthy for Sensitive Groups 25 of 363 days1984: Unhealthy 17 of 363 days1984: Very Unhealthy 5 of 363 days1985: Good 344 of 362 days1985: Moderate 14 of 362 days1985: Unhealthy for Sensitive Groups 4 of 362 days19851986: Good 272 of 359 days1986: Moderate 57 of 359 days1986: Unhealthy for Sensitive Groups 24 of 359 days1986: Unhealthy 5 of 359 days1986: Very Unhealthy 1 of 359 days1987: Good 264 of 364 days1987: Moderate 68 of 364 days1987: Unhealthy for Sensitive Groups 19 of 364 days1987: Unhealthy 12 of 364 days1987: Very Unhealthy 1 of 364 days1988: Good 254 of 358 days1988: Moderate 58 of 358 days1988: Unhealthy for Sensitive Groups 26 of 358 days1988: Unhealthy 13 of 358 days1988: Very Unhealthy 7 of 358 days1989: Good 285 of 363 days1989: Moderate 42 of 363 days1989: Unhealthy for Sensitive Groups 24 of 363 days1989: Unhealthy 10 of 363 days1989: Very Unhealthy 2 of 363 days1990: Good 285 of 363 days1990: Moderate 47 of 363 days1990: Unhealthy for Sensitive Groups 19 of 363 days1990: Unhealthy 8 of 363 days1990: Very Unhealthy 4 of 363 days19901991: Good 279 of 365 days1991: Moderate 49 of 365 days1991: Unhealthy for Sensitive Groups 22 of 365 days1991: Unhealthy 11 of 365 days1991: Very Unhealthy 4 of 365 days1992: Good 258 of 365 days1992: Moderate 60 of 365 days1992: Unhealthy for Sensitive Groups 37 of 365 days1992: Unhealthy 8 of 365 days1992: Very Unhealthy 2 of 365 days1993: Good 261 of 365 days1993: Moderate 68 of 365 days1993: Unhealthy for Sensitive Groups 24 of 365 days1993: Unhealthy 11 of 365 days1993: Very Unhealthy 1 of 365 days1994: Good 284 of 360 days1994: Moderate 53 of 360 days1994: Unhealthy for Sensitive Groups 17 of 360 days1994: Unhealthy 6 of 360 days1995: Good 256 of 365 days1995: Moderate 48 of 365 days1995: Unhealthy for Sensitive Groups 32 of 365 days1995: Unhealthy 26 of 365 days1995: Very Unhealthy 3 of 365 days19951996: Good 309 of 366 days1996: Moderate 42 of 366 days1996: Unhealthy for Sensitive Groups 10 of 366 days1996: Unhealthy 5 of 366 days1997: Good 275 of 365 days1997: Moderate 60 of 365 days1997: Unhealthy for Sensitive Groups 18 of 365 days1997: Unhealthy 10 of 365 days1997: Very Unhealthy 2 of 365 days1998: Good 302 of 364 days1998: Moderate 44 of 364 days1998: Unhealthy for Sensitive Groups 7 of 364 days1998: Unhealthy 11 of 364 days1999: Good 314 of 365 days1999: Moderate 39 of 365 days1999: Unhealthy for Sensitive Groups 11 of 365 days1999: Unhealthy 1 of 365 days2000: Good 179 of 366 days2000: Moderate 137 of 366 days2000: Unhealthy for Sensitive Groups 34 of 366 days2000: Unhealthy 14 of 366 days2000: Very Unhealthy 2 of 366 days20002001: Good 135 of 365 days2001: Moderate 198 of 365 days2001: Unhealthy for Sensitive Groups 26 of 365 days2001: Unhealthy 6 of 365 days2002: Good 154 of 365 days2002: Moderate 177 of 365 days2002: Unhealthy for Sensitive Groups 25 of 365 days2002: Unhealthy 7 of 365 days2002: Very Unhealthy 2 of 365 days2003: Good 122 of 365 days2003: Moderate 202 of 365 days2003: Unhealthy for Sensitive Groups 34 of 365 days2003: Unhealthy 6 of 365 days2003: Very Unhealthy 1 of 365 days2004: Good 140 of 366 days2004: Moderate 179 of 366 days2004: Unhealthy for Sensitive Groups 36 of 366 days2004: Unhealthy 10 of 366 days2004: Very Unhealthy 1 of 366 days2005: Good 67 of 353 days2005: Moderate 237 of 353 days2005: Unhealthy for Sensitive Groups 44 of 353 days2005: Unhealthy 4 of 353 days2005: Very Unhealthy 1 of 353 days20052006: Good 95 of 365 days2006: Moderate 235 of 365 days2006: Unhealthy for Sensitive Groups 28 of 365 days2006: Unhealthy 7 of 365 days2007: Good 93 of 365 days2007: Moderate 245 of 365 days2007: Unhealthy for Sensitive Groups 25 of 365 days2007: Unhealthy 2 of 365 days2008: Good 124 of 360 days2008: Moderate 226 of 360 days2008: Unhealthy for Sensitive Groups 9 of 360 days2008: Unhealthy 1 of 360 days2009: Good 150 of 365 days2009: Moderate 205 of 365 days2009: Unhealthy for Sensitive Groups 10 of 365 days2010: Good 132 of 365 days2010: Moderate 210 of 365 days2010: Unhealthy for Sensitive Groups 21 of 365 days2010: Unhealthy 2 of 365 days20102011: Good 150 of 365 days2011: Moderate 186 of 365 days2011: Unhealthy for Sensitive Groups 26 of 365 days2011: Unhealthy 3 of 365 days2012: Good 150 of 366 days2012: Moderate 197 of 366 days2012: Unhealthy for Sensitive Groups 16 of 366 days2012: Unhealthy 2 of 366 days2012: Very Unhealthy 1 of 366 days2013: Good 160 of 365 days2013: Moderate 198 of 365 days2013: Unhealthy for Sensitive Groups 7 of 365 days2014: Good 180 of 365 days2014: Moderate 182 of 365 days2014: Unhealthy for Sensitive Groups 3 of 365 days2015: Good 209 of 365 days2015: Moderate 146 of 365 days2015: Unhealthy for Sensitive Groups 9 of 365 days2015: Unhealthy 1 of 365 days20152016: Good 237 of 366 days2016: Moderate 126 of 366 days2016: Unhealthy for Sensitive Groups 3 of 366 days2017: Good 213 of 365 days2017: Moderate 149 of 365 days2017: Unhealthy for Sensitive Groups 3 of 365 days2018: Good 161 of 365 days2018: Moderate 196 of 365 days2018: Unhealthy for Sensitive Groups 7 of 365 days2018: Unhealthy 1 of 365 days2019: Good 194 of 365 days2019: Moderate 165 of 365 days2019: Unhealthy for Sensitive Groups 6 of 365 days2020: Good 219 of 363 days2020: Moderate 142 of 363 days2020: Unhealthy for Sensitive Groups 2 of 363 days20202021: Good 231 of 365 days2021: Moderate 131 of 365 days2021: Unhealthy for Sensitive Groups 3 of 365 days2022: Good 203 of 365 days2022: Moderate 157 of 365 days2022: Unhealthy for Sensitive Groups 5 of 365 days2023: Good 140 of 365 days2023: Moderate 216 of 365 days2023: Unhealthy for Sensitive Groups 8 of 365 days2023: Unhealthy 1 of 365 days2024: Good 137 of 366 days2024: Moderate 221 of 366 days2024: Unhealthy for Sensitive Groups 8 of 366 days2025: Good 175 of 365 days2025: Moderate 187 of 365 days2025: Unhealthy for Sensitive Groups 2 of 365 days2025: Unhealthy 1 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 year0501001501980: 90th percentile AQI 1081981: 90th percentile AQI 1011982: 90th percentile AQI 1191983: 90th percentile AQI 1191984: 90th percentile AQI 1151985: 90th percentile AQI 441986: 90th percentile AQI 1001987: 90th percentile AQI 1001988: 90th percentile AQI 1081989: 90th percentile AQI 1001990: 90th percentile AQI 901991: 90th percentile AQI 1011992: 90th percentile AQI 1121993: 90th percentile AQI 1001994: 90th percentile AQI 801995: 90th percentile AQI 1331996: 90th percentile AQI 711997: 90th percentile AQI 931998: 90th percentile AQI 741999: 90th percentile AQI 642000: 90th percentile AQI 1152001: 90th percentile AQI 932002: 90th percentile AQI 1002003: 90th percentile AQI 1012004: 90th percentile AQI 1122005: 90th percentile AQI 1082006: 90th percentile AQI 972007: 90th percentile AQI 872008: 90th percentile AQI 842009: 90th percentile AQI 762010: 90th percentile AQI 902011: 90th percentile AQI 872012: 90th percentile AQI 842013: 90th percentile AQI 702014: 90th percentile AQI 672015: 90th percentile AQI 712016: 90th percentile AQI 662017: 90th percentile AQI 662018: 90th percentile AQI 752019: 90th percentile AQI 672020: 90th percentile AQI 652021: 90th percentile AQI 622022: 90th percentile AQI 662023: 90th percentile AQI 772024: 90th percentile AQI 712025: 90th percentile AQI 671980: Median AQI 351981: Median AQI 281982: Median AQI 381983: Median AQI 381984: Median AQI 371985: Median AQI 281986: Median AQI 351987: Median AQI 381988: Median AQI 401989: Median AQI 321990: Median AQI 341991: Median AQI 371992: Median AQI 411993: Median AQI 401994: Median AQI 361995: Median AQI 381996: Median AQI 321997: Median AQI 351998: Median AQI 331999: Median AQI 322000: Median AQI 512001: Median AQI 542002: Median AQI 522003: Median AQI 552004: Median AQI 542005: Median AQI 602006: Median AQI 582007: Median AQI 572008: Median AQI 552009: Median AQI 522010: Median AQI 542011: Median AQI 532012: Median AQI 522013: Median AQI 522014: Median AQI 512015: Median AQI 472016: Median AQI 452017: Median AQI 472018: Median AQI 532019: Median AQI 492020: Median AQI 462021: Median AQI 442022: Median AQI 482023: Median AQI 542024: Median AQI 532025: Median AQI 511980198519901995200020052010201520202025
  • 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)22060%
Ozone14540%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536517518721005167160PM2.5
202436613722180005371143PM2.5
202336514021681005477154PM2.5
202236520315750004866129PM2.5
202136523113130004462115PM2.5
202036321914220004665122PM2.5
201936519416560004967150PM2.5
201836516119671005375154PM2.5
201736521314930004766133PM2.5
201636623712630004566122Ozone
201536520914691004771164PM2.5
201436518018230005167133PM2.5
201336516019870005270122PM2.5
2012366150197162105284207PM2.5
2011365150186263005387185PM2.5
2010365132210212005490164PM2.5
2009365150205100005276147PM2.5
200836012422691005584161PM2.5
200736593245252005787169PM2.5
200636595235287005897174PM2.5
2005353672374441060108204PM2.5
200436614017936101054112203PM2.5
20033651222023461055101209PM2.5
20023651541772572052100217PM2.5
2001365135198266005493197PM2.5
200036617913734142051115210Ozone
199936531439111003264161Ozone
199836430244711003374185Ozone
1997365275601810203593205Ozone
199636630942105003271172Ozone
19953652564832263038133213Ozone
199436028453176003680177Ozone
19933652616824111040100208Ozone
1992365258603782041112205Ozone
19913652794922114037101212Ozone
199036328547198403490212Ozone
19893632854224102032100212Ozone
19883582545826137040108226Ozone
19873642646819121038100232Ozone
1986359272572451035100217Ozone
19853623441440002844133Ozone
19843632635325175037115224Ozone
19833372365425175038119219Ozone
1982350241623296038119251Ozone
19813602903221143028101210Ozone
19803362475510168035108235Ozone

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 1980–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem