EnviroNearby

Collin County, Texas air quality history

Daily Air Quality Index summaries from EPA monitors in Collin, Texas, 1986–2025.

76%
Good days in 2025
40
Median daily AQI, 2025
23
Days above 100 in 2025
359
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Collin, Texas on 359 days. 272 of those days (76%) were in the Good range, and the median daily AQI was 40. That median is lower than the typical monitored county in Texas (median 43.5 across 44 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 359 days. Across the years with fuller monitoring, the share of Good days rose: an average of 66% in 1986–1993 versus 76% 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%1986: Good 82 of 159 days1986: Moderate 42 of 159 days1986: Unhealthy for Sensitive Groups 20 of 159 days1986: Unhealthy 14 of 159 days1986: Very Unhealthy 1 of 159 days19861992: Good 143 of 213 days1992: Moderate 42 of 213 days1992: Unhealthy for Sensitive Groups 24 of 213 days1992: Unhealthy 2 of 213 days1992: Very Unhealthy 2 of 213 days1993: Good 247 of 315 days1993: Moderate 41 of 315 days1993: Unhealthy for Sensitive Groups 18 of 315 days1993: Unhealthy 9 of 315 days1994: Good 216 of 321 days1994: Moderate 61 of 321 days1994: Unhealthy for Sensitive Groups 22 of 321 days1994: Unhealthy 21 of 321 days1994: Very Unhealthy 1 of 321 days1995: Good 201 of 316 days1995: Moderate 58 of 316 days1995: Unhealthy for Sensitive Groups 39 of 316 days1995: Unhealthy 14 of 316 days1995: Very Unhealthy 4 of 316 days1996: Good 251 of 355 days1996: Moderate 73 of 355 days1996: Unhealthy for Sensitive Groups 23 of 355 days1996: Unhealthy 7 of 355 days1996: Very Unhealthy 1 of 355 days19961997: Good 236 of 354 days1997: Moderate 71 of 354 days1997: Unhealthy for Sensitive Groups 29 of 354 days1997: Unhealthy 17 of 354 days1997: Very Unhealthy 1 of 354 days1998: Good 220 of 359 days1998: Moderate 72 of 359 days1998: Unhealthy for Sensitive Groups 46 of 359 days1998: Unhealthy 21 of 359 days1999: Good 248 of 364 days1999: Moderate 73 of 364 days1999: Unhealthy for Sensitive Groups 28 of 364 days1999: Unhealthy 12 of 364 days1999: Very Unhealthy 3 of 364 days2000: Good 208 of 366 days2000: Moderate 103 of 366 days2000: Unhealthy for Sensitive Groups 36 of 366 days2000: Unhealthy 18 of 366 days2000: Very Unhealthy 1 of 366 days2001: Good 206 of 365 days2001: Moderate 114 of 365 days2001: Unhealthy for Sensitive Groups 34 of 365 days2001: Unhealthy 11 of 365 days20012002: Good 233 of 365 days2002: Moderate 104 of 365 days2002: Unhealthy for Sensitive Groups 23 of 365 days2002: Unhealthy 5 of 365 days2003: Good 241 of 365 days2003: Moderate 89 of 365 days2003: Unhealthy for Sensitive Groups 31 of 365 days2003: Unhealthy 3 of 365 days2003: Very Unhealthy 1 of 365 days2004: Good 284 of 362 days2004: Moderate 53 of 362 days2004: Unhealthy for Sensitive Groups 16 of 362 days2004: Unhealthy 9 of 362 days2005: Good 248 of 363 days2005: Moderate 68 of 363 days2005: Unhealthy for Sensitive Groups 37 of 363 days2005: Unhealthy 10 of 363 days2006: Good 245 of 359 days2006: Moderate 73 of 359 days2006: Unhealthy for Sensitive Groups 31 of 359 days2006: Unhealthy 10 of 359 days20062007: Good 278 of 361 days2007: Moderate 65 of 361 days2007: Unhealthy for Sensitive Groups 16 of 361 days2007: Unhealthy 2 of 361 days2008: Good 273 of 365 days2008: Moderate 78 of 365 days2008: Unhealthy for Sensitive Groups 13 of 365 days2008: Unhealthy 1 of 365 days2009: Good 278 of 360 days2009: Moderate 68 of 360 days2009: Unhealthy for Sensitive Groups 14 of 360 days2010: Good 296 of 365 days2010: Moderate 64 of 365 days2010: Unhealthy for Sensitive Groups 4 of 365 days2010: Unhealthy 1 of 365 days2011: Good 257 of 360 days2011: Moderate 71 of 360 days2011: Unhealthy for Sensitive Groups 25 of 360 days2011: Unhealthy 7 of 360 days20112012: Good 256 of 358 days2012: Moderate 72 of 358 days2012: Unhealthy for Sensitive Groups 27 of 358 days2012: Unhealthy 3 of 358 days2013: Good 277 of 362 days2013: Moderate 71 of 362 days2013: Unhealthy for Sensitive Groups 14 of 362 days2014: Good 299 of 361 days2014: Moderate 57 of 361 days2014: Unhealthy for Sensitive Groups 5 of 361 days2015: Good 304 of 360 days2015: Moderate 47 of 360 days2015: Unhealthy for Sensitive Groups 9 of 360 days2016: Good 318 of 363 days2016: Moderate 41 of 363 days2016: Unhealthy for Sensitive Groups 4 of 363 days20162017: Good 313 of 363 days2017: Moderate 43 of 363 days2017: Unhealthy for Sensitive Groups 7 of 363 days2018: Good 296 of 361 days2018: Moderate 49 of 361 days2018: Unhealthy for Sensitive Groups 16 of 361 days2019: Good 309 of 365 days2019: Moderate 48 of 365 days2019: Unhealthy for Sensitive Groups 7 of 365 days2019: Unhealthy 1 of 365 days2020: Good 317 of 365 days2020: Moderate 45 of 365 days2020: Unhealthy for Sensitive Groups 2 of 365 days2020: Unhealthy 1 of 365 days2021: Good 294 of 357 days2021: Moderate 55 of 357 days2021: Unhealthy for Sensitive Groups 7 of 357 days2021: Unhealthy 1 of 357 days20212022: Good 289 of 359 days2022: Moderate 63 of 359 days2022: Unhealthy for Sensitive Groups 7 of 359 days2023: Good 261 of 356 days2023: Moderate 74 of 356 days2023: Unhealthy for Sensitive Groups 19 of 356 days2023: Unhealthy 2 of 356 days2024: Good 283 of 365 days2024: Moderate 71 of 365 days2024: Unhealthy for Sensitive Groups 8 of 365 days2024: Unhealthy 3 of 365 days2025: Good 272 of 359 days2025: Moderate 64 of 359 days2025: Unhealthy for Sensitive Groups 20 of 359 days2025: Unhealthy 3 of 359 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 year0501001501986: 90th percentile AQI 1501992: 90th percentile AQI 1121993: 90th percentile AQI 931994: 90th percentile AQI 1261995: 90th percentile AQI 1261996: 90th percentile AQI 971997: 90th percentile AQI 1151998: 90th percentile AQI 1361999: 90th percentile AQI 1082000: 90th percentile AQI 1292001: 90th percentile AQI 1122002: 90th percentile AQI 912003: 90th percentile AQI 972004: 90th percentile AQI 872005: 90th percentile AQI 1122006: 90th percentile AQI 1052007: 90th percentile AQI 872008: 90th percentile AQI 772009: 90th percentile AQI 772010: 90th percentile AQI 672011: 90th percentile AQI 1002012: 90th percentile AQI 932013: 90th percentile AQI 772014: 90th percentile AQI 612015: 90th percentile AQI 672016: 90th percentile AQI 582017: 90th percentile AQI 642018: 90th percentile AQI 712019: 90th percentile AQI 582020: 90th percentile AQI 542021: 90th percentile AQI 642022: 90th percentile AQI 712023: 90th percentile AQI 802024: 90th percentile AQI 772025: 90th percentile AQI 901986: Median AQI 491992: Median AQI 441993: Median AQI 371994: Median AQI 421995: Median AQI 421996: Median AQI 411997: Median AQI 411998: Median AQI 441999: Median AQI 412000: Median AQI 452001: Median AQI 472002: Median AQI 442003: Median AQI 422004: Median AQI 382005: Median AQI 422006: Median AQI 422007: Median AQI 382008: Median AQI 412009: Median AQI 382010: Median AQI 382011: Median AQI 412012: Median AQI 422013: Median AQI 402014: Median AQI 372015: Median AQI 362016: Median AQI 372017: Median AQI 392018: Median AQI 372019: Median AQI 402020: Median AQI 372021: Median AQI 372022: Median AQI 402023: Median AQI 412024: Median AQI 402025: Median AQI 4019861996200120062011201620212025
  • 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
Ozone359100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202535927264203004090156Ozone
20243652837183004077161Ozone
202335626174192004180154Ozone
20223592896370004071143Ozone
20213572945571003764154Ozone
20203653174521003754154Ozone
20193653094871004058156Ozone
201836129649160003771150Ozone
20173633134370003964122Ozone
20163633184140003758119Ozone
20153603044790003667143Ozone
20143612995750003761143Ozone
201336227771140004077140Ozone
201235825672273004293159Ozone
2011360257712570041100174Ozone
20103652966441003867154Ozone
200936027868140003877150Ozone
200836527378131004177169Ozone
200736127865162003887169Ozone
20063592457331100042105195Ozone
20053632486837100042112177Ozone
200436228453169003887187Ozone
200336524189313104297201Ozone
2002365233104235004491187Ozone
200136520611434110047112197Ozone
200036620810336181045129201Ozone
19993642487328123041108222Ozone
19983592207246210044136192Ozone
19973542367129171041115209Ozone
199635525173237104197205Ozone
19953162015839144042126209Ozone
19943212166122211042126204Ozone
199331524741189003793192Ozone
1992213143422422044112212Ozone
1986159824220141049150210Ozone

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 1986–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem