EnviroNearby

Knox County, Tennessee air quality history

Daily Air Quality Index summaries from EPA monitors in Knox, Tennessee, 1980–2025.

63%
Good days in 2025
46
Median daily AQI, 2025
1
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 Knox, Tennessee on 365 days. 230 of those days (63%) were in the Good range, and the median daily AQI was 46. That median is higher than the typical monitored county in Tennessee (median 39 across 23 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 275 days. Across the years with fuller monitoring, the share of Good days rose: an average of 37% in 1980–1982 versus 54% 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 171 of 363 days1980: Moderate 129 of 363 days1980: Unhealthy for Sensitive Groups 30 of 363 days1980: Unhealthy 28 of 363 days1980: Very Unhealthy 5 of 363 days19801981: Good 60 of 365 days1981: Moderate 226 of 365 days1981: Unhealthy for Sensitive Groups 55 of 365 days1981: Unhealthy 24 of 365 days1982: Good 178 of 365 days1982: Moderate 125 of 365 days1982: Unhealthy for Sensitive Groups 44 of 365 days1982: Unhealthy 15 of 365 days1982: Very Unhealthy 3 of 365 days1983: Good 227 of 363 days1983: Moderate 87 of 363 days1983: Unhealthy for Sensitive Groups 42 of 363 days1983: Unhealthy 7 of 363 days1984: Good 215 of 366 days1984: Moderate 125 of 366 days1984: Unhealthy for Sensitive Groups 23 of 366 days1984: Unhealthy 3 of 366 days1985: Good 220 of 364 days1985: Moderate 102 of 364 days1985: Unhealthy for Sensitive Groups 39 of 364 days1985: Unhealthy 3 of 364 days19851986: Good 160 of 339 days1986: Moderate 152 of 339 days1986: Unhealthy for Sensitive Groups 21 of 339 days1986: Unhealthy 6 of 339 days1987: Good 128 of 279 days1987: Moderate 90 of 279 days1987: Unhealthy for Sensitive Groups 40 of 279 days1987: Unhealthy 21 of 279 days1988: Good 214 of 338 days1988: Moderate 73 of 338 days1988: Unhealthy for Sensitive Groups 26 of 338 days1988: Unhealthy 18 of 338 days1988: Very Unhealthy 7 of 338 days1989: Good 293 of 363 days1989: Moderate 66 of 363 days1989: Unhealthy for Sensitive Groups 4 of 363 days1990: Good 237 of 362 days1990: Moderate 74 of 362 days1990: Unhealthy for Sensitive Groups 35 of 362 days1990: Unhealthy 14 of 362 days1990: Very Unhealthy 2 of 362 days19901991: Good 248 of 365 days1991: Moderate 75 of 365 days1991: Unhealthy for Sensitive Groups 34 of 365 days1991: Unhealthy 8 of 365 days1992: Good 277 of 366 days1992: Moderate 72 of 366 days1992: Unhealthy for Sensitive Groups 14 of 366 days1992: Unhealthy 3 of 366 days1993: Good 224 of 363 days1993: Moderate 89 of 363 days1993: Unhealthy for Sensitive Groups 36 of 363 days1993: Unhealthy 14 of 363 days1994: Good 267 of 365 days1994: Moderate 78 of 365 days1994: Unhealthy for Sensitive Groups 15 of 365 days1994: Unhealthy 5 of 365 days1995: Good 262 of 365 days1995: Moderate 70 of 365 days1995: Unhealthy for Sensitive Groups 22 of 365 days1995: Unhealthy 10 of 365 days1995: Very Unhealthy 1 of 365 days19951996: Good 240 of 366 days1996: Moderate 74 of 366 days1996: Unhealthy for Sensitive Groups 40 of 366 days1996: Unhealthy 10 of 366 days1996: Very Unhealthy 2 of 366 days1997: Good 234 of 365 days1997: Moderate 70 of 365 days1997: Unhealthy for Sensitive Groups 41 of 365 days1997: Unhealthy 19 of 365 days1997: Very Unhealthy 1 of 365 days1998: Good 207 of 361 days1998: Moderate 64 of 361 days1998: Unhealthy for Sensitive Groups 49 of 361 days1998: Unhealthy 31 of 361 days1998: Very Unhealthy 10 of 361 days1999: Good 120 of 365 days1999: Moderate 153 of 365 days1999: Unhealthy for Sensitive Groups 61 of 365 days1999: Unhealthy 30 of 365 days1999: Very Unhealthy 1 of 365 days2000: Good 51 of 366 days2000: Moderate 255 of 366 days2000: Unhealthy for Sensitive Groups 44 of 366 days2000: Unhealthy 14 of 366 days2000: Very Unhealthy 2 of 366 days20002001: Good 50 of 365 days2001: Moderate 269 of 365 days2001: Unhealthy for Sensitive Groups 35 of 365 days2001: Unhealthy 11 of 365 days2002: Good 47 of 365 days2002: Moderate 262 of 365 days2002: Unhealthy for Sensitive Groups 39 of 365 days2002: Unhealthy 17 of 365 days2003: Good 66 of 365 days2003: Moderate 278 of 365 days2003: Unhealthy for Sensitive Groups 15 of 365 days2003: Unhealthy 6 of 365 days2004: Good 71 of 366 days2004: Moderate 283 of 366 days2004: Unhealthy for Sensitive Groups 11 of 366 days2004: Unhealthy 1 of 366 days2005: Good 61 of 365 days2005: Moderate 264 of 365 days2005: Unhealthy for Sensitive Groups 36 of 365 days2005: Unhealthy 4 of 365 days20052006: Good 73 of 365 days2006: Moderate 264 of 365 days2006: Unhealthy for Sensitive Groups 24 of 365 days2006: Unhealthy 4 of 365 days2007: Good 65 of 359 days2007: Moderate 238 of 359 days2007: Unhealthy for Sensitive Groups 49 of 359 days2007: Unhealthy 6 of 359 days2007: Very Unhealthy 1 of 359 days2008: Good 150 of 288 days2008: Moderate 115 of 288 days2008: Unhealthy for Sensitive Groups 19 of 288 days2008: Unhealthy 4 of 288 days2009: Good 245 of 321 days2009: Moderate 74 of 321 days2009: Unhealthy for Sensitive Groups 2 of 321 days2010: Good 209 of 322 days2010: Moderate 100 of 322 days2010: Unhealthy for Sensitive Groups 13 of 322 days20102011: Good 194 of 261 days2011: Moderate 59 of 261 days2011: Unhealthy for Sensitive Groups 8 of 261 days2012: Good 158 of 265 days2012: Moderate 90 of 265 days2012: Unhealthy for Sensitive Groups 14 of 265 days2012: Unhealthy 2 of 265 days2012: Very Unhealthy 1 of 265 days2013: Good 161 of 362 days2013: Moderate 201 of 362 days2014: Good 144 of 362 days2014: Moderate 218 of 362 days2015: Good 182 of 365 days2015: Moderate 182 of 365 days2015: Unhealthy for Sensitive Groups 1 of 365 days20152016: Good 167 of 366 days2016: Moderate 192 of 366 days2016: Unhealthy for Sensitive Groups 4 of 366 days2016: Unhealthy 3 of 366 days2017: Good 269 of 361 days2017: Moderate 92 of 361 days2018: Good 186 of 364 days2018: Moderate 177 of 364 days2018: Unhealthy for Sensitive Groups 1 of 364 days2019: Good 214 of 364 days2019: Moderate 150 of 364 days2020: Good 233 of 366 days2020: Moderate 133 of 366 days20202021: Good 153 of 365 days2021: Moderate 207 of 365 days2021: Unhealthy for Sensitive Groups 5 of 365 days2022: Good 185 of 365 days2022: Moderate 180 of 365 days2023: Good 162 of 365 days2023: Moderate 199 of 365 days2023: Unhealthy for Sensitive Groups 4 of 365 days2024: Good 205 of 366 days2024: Moderate 160 of 366 days2024: Unhealthy for Sensitive Groups 1 of 366 days2025: Good 230 of 365 days2025: Moderate 134 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 year0501001502001980: 90th percentile AQI 1431981: 90th percentile AQI 1361982: 90th percentile AQI 1261983: 90th percentile AQI 1151984: 90th percentile AQI 931985: 90th percentile AQI 1051986: 90th percentile AQI 971987: 90th percentile AQI 1361988: 90th percentile AQI 1291989: 90th percentile AQI 611990: 90th percentile AQI 1151991: 90th percentile AQI 1051992: 90th percentile AQI 841993: 90th percentile AQI 1121994: 90th percentile AQI 801995: 90th percentile AQI 931996: 90th percentile AQI 1191997: 90th percentile AQI 1331998: 90th percentile AQI 1561999: 90th percentile AQI 1402000: 90th percentile AQI 1222001: 90th percentile AQI 1082002: 90th percentile AQI 1262003: 90th percentile AQI 902004: 90th percentile AQI 872005: 90th percentile AQI 1012006: 90th percentile AQI 932007: 90th percentile AQI 1082008: 90th percentile AQI 932009: 90th percentile AQI 642010: 90th percentile AQI 842011: 90th percentile AQI 732012: 90th percentile AQI 842013: 90th percentile AQI 642014: 90th percentile AQI 652015: 90th percentile AQI 662016: 90th percentile AQI 692017: 90th percentile AQI 602018: 90th percentile AQI 652019: 90th percentile AQI 622020: 90th percentile AQI 602021: 90th percentile AQI 692022: 90th percentile AQI 632023: 90th percentile AQI 682024: 90th percentile AQI 642025: 90th percentile AQI 601980: Median AQI 541981: Median AQI 731982: Median AQI 511983: Median AQI 441984: Median AQI 461985: Median AQI 471986: Median AQI 511987: Median AQI 541988: Median AQI 431989: Median AQI 391990: Median AQI 421991: Median AQI 431992: Median AQI 381993: Median AQI 431994: Median AQI 391995: Median AQI 371996: Median AQI 391997: Median AQI 391998: Median AQI 451999: Median AQI 682000: Median AQI 692001: Median AQI 682002: Median AQI 642003: Median AQI 622004: Median AQI 632005: Median AQI 642006: Median AQI 622007: Median AQI 642008: Median AQI 502009: Median AQI 392010: Median AQI 442011: Median AQI 362012: Median AQI 462013: Median AQI 522014: Median AQI 532015: Median AQI 512016: Median AQI 522017: Median AQI 412018: Median AQI 502019: Median AQI 462020: Median AQI 442021: Median AQI 522022: Median AQI 492023: Median AQI 522024: Median AQI 482025: Median AQI 461980198519901995200020052010201520202025
  • 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)27575%
Ozone9025%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536523013401004660156PM2.5
202436620516010004864105PM2.5
202336516219940005268149PM2.5
20223651851800000496377PM2.5
202136515320750005269150PM2.5
20203662331330000446091PM2.5
20193642141500000466284PM2.5
201836418617710005065112PM2.5
20173612699200004160100Ozone
201636616719243005269175PM2.5
201536518218210005166101PM2.5
20143621442180000536584PM2.5
20133621612010000526487PM2.5
201226515890142104684217Ozone
20112611945980003673119Ozone
2010322209100130004484133Ozone
20093212457420003964129Ozone
2008288150115194005093174Ozone
2007359652384961064108215PM2.5
200636573264244006293161PM2.5
2005365612643640064101166PM2.5
200436671283111006387177PM2.5
200336566278156006290187PM2.5
20023654726239170064126195PM2.5
20013655026935110068108187PM2.5
20003665125544142069122218PM2.5
199936512015361301068140207Ozone
199836120764493110045156218Ozone
19973652347041191039133206Ozone
19963662407440102039119206Ozone
1995365262702210103793202Ozone
199436526778155003980182Ozone
19933632248936140043112200Ozone
199236627772143003884166Ozone
1991365248753480043105177Ozone
19903622377435142042115209Ozone
19893632936640003961136CO
19883382147326187043129226Ozone
19872791289040210054136190Ozone
1986339160152216005197182Ozone
19853642201023930047105156CO
1984366215125233004693174CO
1983363227874270044115172Ozone
198236517812544153051126203Ozone
19813656022655240073136200CO
198036317112930285054143242Ozone

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 Tennessee with a similar median AQI in 2025

All monitored counties in Tennessee

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